Replacement the virtual switch within Windows Server 2012 Hyper-V with a Cisco switch

Perhaps replace isn’t the right word, but you can certainly augment the virtual switch to the point of complete transformation. Cisco is offering the Nexus 1000V virtual switch to install alongside the virtual switch in Windows Server 2012, turning it into a fully managed, standards-compliant switch with a console — one that even supports software-defined networking (SDN) and the Cisco Open Network Environment. You can do this with competitor VMware, but at an additional cost; you get this capability built into the underlying operating system license with Hyper-V.

There are three supported types of extensibility with the switch

hird parties and in-house development teams can create these switch extensions to extend the functionality of the switch, like Cisco did. You can create capturing extensions that read and inspect traffic but are unable to modify or drop packets. You also can create filtering extensions that inspect and read traffic, drop, insert and modify packets directly into the transmissions stream; firewall extensions for the virtual switch typically won’t use this type of filter. And finally, you can create forwarding extensions that define the destination of packets to different places, as well as capture and filter traffic. The capabilities of each type of extension build on one another.

The extensible switch supports access control lists via ports

This is really useful in multi-tenant deployments, where there are hosted virtual machines (VMs) for a variety of clients on the same set of machines, or for organizations with Chinese firewall-type regulations that require data and access segregation. These companies can now use the same type of security right in the Hyper-V virtual network that has been possible in physical switches and network security devices. The Hyper-V virtual switch can filter port traffic based on IP addresses or ranges or via MAC addresses to identify the specific virtual network interface cards involved and ensure that networks are isolated. This also works with the isolated or private VLAN feature that lets the administrator set up isolated communities of tenants by securing traffic over individual VLANs within the virtual network.

There are trunking tools new to Windows that exist within the Hyper-V virtual switch

There is a set of traffic-routing capabilities that can run within a VM — making it like an appliance — as a switch extension (as previously described) or as a service on the hypervisor host. The designated monitoring port copies traffic to the specified VM. When you set the “trunk mode” on a given virtual switch port, all traffic on the virtual network is routed to that VM, making it sit “in front” of the traffic. Traffic is then distributed to other VMs. You can also create a capture extension instance that copies the traffic to a given service for other types of inspection or analysis, and you can set up another extension to tunnel traffic to another network destination as well.

You can manage the Hyper-V extensible virtual switch as an independent device from within System Center 2012

If you have deployed System Center 2012 Service Pack 1, you can add a virtual switch extension manager right to the Virtual Machine Manager console to monitor and manage the settings, features and capabilities of your VMs and the switch from within a single console. You can also do this with other virtual switch extension vendors like Cisco, but you need to first obtain provider software from the vendor, install it on the Virtual Machine Manager server and restart the service.

Cluster startup without Active Directory

Perhaps one of the most catastrophic events a cluster can face is when it can’t contact a domain controller (DC) during formation. A different scenario leading to this same problem occurs when you attempt to virtualize your DCs as virtual machines in a Windows failover cluster. The cluster must contact a DC to start, but the virtual DC can’t start until the cluster does. This reliance on AD for a cluster to form has been eliminated in Windows Server 2012.

You’ll need to create a Windows Server 2012 cluster by contacting a DC and storing its authentication data in AD, along with any cluster members, for this function to work. Then existing clusters can start up without having to first contact a DC for authentication. Prior to Windows Server 2012, cluster startup was supported, although not recommended, to run the AD Services role on cluster members to make them more resilient to AD connectivity issues. It is no longer necessary, nor is it supported to run domain controllers as cluster nodes as Microsoft documents in KB 281662.

Flexible OU administration

Another AD shortcoming that has been addressed in Windows Server 2012 is the ability to specify in which organizational units (OU) the computer objects for the cluster will be created. In the past, when a cluster was created, the Cluster Name Object (CNO) was created in the default Computers container in the OU where the cluster members reside. This prevented admins from delegating control to specific OUs for the purpose of managing Failover Clusters without going through painful prestaging efforts.

In Windows Server 2012, both the Create Cluster Wizard and the PowerShell cmdlet New-Cluster allow you to specify in which OU the CNO will be created. In addition, any Virtual Computer Objects (VCO) for the network names associated with highly available cluster roles will be created in the same OU. The user account that creates the cluster must have the Create Computer Objects permission in the specified OU. In turn, the newly created CNO must have Create Computer Objects permission to create VCOs. You can move all these computer objects to a different OU at any point — without disrupting the cluster. Keep in mind the custom OU must be created before you create your cluster.

Unfortunately, the syntax for specifying a particular OU where the CNO should be created isn’t intuitive in the Create Cluster Wizard or the corresponding PowerShell New-Cluster cmdlet. The Create Cluster Wizard will create appropriate syntax for specifying the distinguished name of the cluster, along with the OU where it will reside. In our example, the name of the cluster is Win2012Clus1, and its CNO will be created in the ClusterServers OU in the fictitious windows-scripting.info domain.

Next, look at the syntax for creating a cluster using the PowerShell New-Cluster cmdlet. In this example, the command creates a cluster with the name Win2012Cluster1, placing the CNO in the ClusterServers OU in the fictitious domain using a static IP address of 192.168.0.252.

fter you create the Windows failover cluster, use Active Directory Users and Computers to view and manage the new CNO placed in the custom OU called ClusterServers. Any new cluster roles that are configured will create their VCO in the same OU.

Additional cluster and Active Directory enhancements

With Windows Server 2012, you can have a failover cluster located in a remote branch office or behind a DMZ with a Read-Only Domain Controller (RODC). While the CNO and VCOs must be created beforehand on a RWDC as described by Microsoft, the server supports the configuration.

Finally, AD Cluster computer objects are now created with the Protect Object from Accidental Deletion flag to ensure automated stale object scripts don’t delete them. If the account that creates the cluster doesn’t have this right for the OU, it will still create the object, but won’t protect it from accidental deletion. A system event ID 1222 will be logged to alert you, and you can follow Microsoft KB 2770582 to fix the issue.

Microsoft has taken several steps in Windows Server 2012 to address the AD pitfalls that Windows failover clusters have endured over the years. Some of the top integration enhancements include booting clusters without AD, more flexible OU administration, support for clusters in Branch Offices and DMZs with RODCs and protecting cluster AD objects from deletion.

But the problem isn’t how much you’re storing or how fast you can get to it. The problem is whether the improvements in storage per gigabyte or I/O throughputs are being outpaced by the amount of data being stored in your organization. The more we can store, the more we do store. And while deduplication is not a magic bullet, it is one of many strategies that can be used to cut into data storage demands.

Microsoft added a deduplication subsystem feature in Windows Server 2012, which provides a way to perform deduplication on all volumes managed by a given instance of Windows Server. Instead of relegating deduplication duty to a piece of hardware or a software layer, it’s done in the OS on both a block and file level — meaning that many kinds of data (such as multiple instances of a virtual machine) can be successfully deduplicated with minimal overhead.

If you plan to implement Windows Server 2012 deduplication technology, be sure you understand these seven points:

1. Deduplication is not enabled by default

Don’t upgrade to Windows Server 2012 and expect to see space savings automatically appear. Deduplication is treated as a file-and-storage service feature, rather than a core OS component. To that end, you must enable it and manually configure it in Server Roles | File And Storage Services | File and iSCSI Services. Once enabled, it also needs to be configured on a volume-by-volume basis.

2. Deduplication won’t burden the system

Microsoft put a fair amount of thought into setting up deduplication so it has a small system footprint and can run even on servers that have a heavy load. Here are three reasons why:

a. Content is only deduplicated after n number of days, with n being 5 by default, but this is user-configurable. This time delay keeps the deduplicator from trying to process content that is currently and aggressively being used or from processing files as they’re being written to disk (which would constitute a major performance hit).

b. Deduplication can be constrained by directory or file type. If you want to exclude certain kinds of files or folders from deduplication, you can specify those as well.

c. The deduplication process is self-throttling and can be run at varying priority levels. You can set the actual deduplication process to run at low priority and it will pause itself if the system is under heavy load. You can also set a window of time for the deduplicator to run at full speed, during off-hours, for example.

This way, with a little admin oversight, deduplication can be put into place on even a busy server and not impact its performance.

3. Deduplicated volumes are ‘atomic units’

‘Atomic units’ mean that all of the deduplication information about a given volume is kept on that volume, so it can be moved without injury to another system that supports deduplication. If you move it to a system that doesn’t have deduplication, you’ll only be able to see the nondeduplicated files. The best rule is not to move a deduplicated volume unless it’s to another Windows Server 2012 machine.

4. Deduplication works with BranchCache

If you have a branch server also running deduplication, it shares data about deduped files with the central server and thus cuts down on the amount of data needed to be sent between the two.

5. Backing up deduplicated volumes can be tricky

A block-based backup solution — e.g., a disk-image backup method — should work as-is and will preserve all deduplication data.

File-based backups will also work, but they won’t preserve deduplication data unless they’re dedupe-aware. They’ll back up everything in its original, discrete, undeduplicated form. What’s more, this means backup media should be large enough to hold the undeduplicated data as well.

The native Windows Server Backup solution is dedupe-aware, although any third-party backup products for Windows Server 2012 should be checked to see if deduplication awareness is either present or being added in a future revision.

6. More is better when it comes to cores and memory

Microsoft recommends devoting at least one CPU core and 350 MB of free memory to process one volume at a time, with around 100 GB of storage processed in an hour (without interruptions) or around 2 TB a day. The more parallelism you have to spare, the more volumes you can simultaneously process.

7. Deduplication mileage may vary

Microsoft has crunched its own numbers and found that the nature of the deployment affected the amount of space savings. Multiple OS instances on virtual hard disks (VHDs) exhibited a great deal of savings because of the amount of redundant material between them; user folders, less so.

In its rundown of what are good and bad candidates for deduping, Microsoft notes that live Exchange Server databases are actually poor candidates. This sounds counterintuitive; you’d think an Exchange mailbox database might have a lot of redundant data in it. But the constantly changing nature of data (messages being moved, deleted, created, etc.) offsets the gains in throughput and storage savings made by deduplication. However, an Exchange Server backup volume is a better candidate since it changes less often and can be deduplicated without visibly slowing things down.

How much you actually get from deduplication in your particular setting is the real test for whether to use it. Therefore, it’s best to start provisionally, perhaps on a staging server where you can set the “crawl rate” for deduplication as high as needed, see how much space savings you get with your data and then establish a schedule for performing deduplication on your own live servers.

In addition to dynamic quorum, multisite geoclusters now benefit from the ability to specify which nodes receive votes and which ones don’t. This allows you to bias a particular site (e.g., the primary site) to have the controlling votes, or nodes, to maintain quorum. This also prevents a split-brain scenario from occurring as the secondary site tries to update the cluster database when the primary site is down

Configuring Dynamic Quorum in Windows Server 2012

The principle behind quorum in a failover cluster environment is to ensure that only a majority of nodes can form and participate in a cluster. This prevents a second subset of nodes from forming a separate cluster that can access the same shared resources in an uncoordinated fashion, which can lead to corruption. When nodes are shut down or fail, there are fewer active nodes remaining to maintain the static quorum value of votes needed for the cluster to function. The new Dynamic Quorum Management dynamically adjusts the votes of remaining active nodes to ensure that quorum can be maintained in the event of yet another node failure or shutdown.

There are a few requirements that must be met before the Dynamic Quorum mechanism kicks in. First, Dynamic Quorum must be enabled, which it is, by default, in Windows Server 2012. The Failover Cluster Manager can be used to view or modify the Dynamic Quorum option by running the Configure Cluster Quorum Wizard. Start the wizard by highlighting the cluster in the left-hand pane, right-clicking on it, selecting More Actions and then choosing Configure Cluster Quorum Settings.

The Quorum Wizard prompts you to select from several different quorum configurations depending on your environment (Typical, Add/Change or Advanced). By default, the cluster will use the typical settings for your configuration to establish the quorum management options. You can also add or change the quorum witness if one was selected during the installation process.

To view or change the Dynamic Quorum Management option, use the Advanced quorum configuration option, as seen above. Stepping through the Quorum Wizard, it will prompt you to Configure Quorum Management. This is where you can view or change the Dynamic Quorum option.

You can also view or modify the cluster’s Dynamic Quorum setting by using PowerShell cmdlets. The first cmdlet, Get-Cluster, as shown in below, reveals the current Dynamic Quorum setting (0=disabled, 1=enabled). You can then use PowerShell to enable Dynamic Quorum by establishing the variable $cluster with Get-Cluster and then set the property DynamicQuorum to a value of 1.

With Dynamic Quorum enabled, the next condition that must be met is that the cluster must be up and running and currently sustaining quorum based on the initial cluster configuration. The final condition for Dynamic Quorum to work is that any subsequent node failures or shutdowns must be experienced sequentially — not with multiple nodes going down at the same time. A lengthier cluster regroup operation would occur if multiple nodes exited the cluster simultaneously.

You can use PowerShell to view the number of votes and observe the inner workings of the Dynamic Quorum mechanism. By default, each server in the cluster gets a single vote, or NodeWeight. When Dynamic Quorum is enabled, an additional property called DynamicWeight is used to track a server’s dynamic vote toward quorum. The cluster will adjust a node’s dynamic weight to zero, if necessary, to avoid losing quorum, should another node exit the cluster. The PowerShell cmdlet reveals the NodeWeight and DynamicWeight for a two-node cluster.

Dynamic Quorum allows cluster nodes to be individually shut down or fail to the point where just a single node is left functioning (“last man standing”). Just as quorum is dynamically adjusted downward as nodes fail or are shut down in the cluster, quorum is adjusted upward as nodes are rebooted back into the cluster.

Using weighted votes to assign nodes

The other major enhancement to the quorum mechanism in Windows Server 2012 is the ability to specify which nodes in a cluster receive a vote. As mentioned, all nodes receive a vote that contributes toward quorum by default. In multisite geocluster configurations, it may be beneficial to give nodes in the primary site a vote to ensure they keep running in the event of a network failure between sites. Nodes in the secondary site can be configured with zero votes so they cannot form a cluster.

You can use the Quorum Wizard (Advanced Quorum Configurations) to configure whether a node receives a vote. The wizard also allows you to see how Node1 is given a vote and Node2 is not.

Alternatively, you can use PowerShell to specify whether a node receives a vote. Use the Get-ClusterNode cmdlet to set the NodeWeight for Node2 back to 1 so that it receives a vote.

Windows Server 2012 has made significant improvements to the quorum mechanism, resulting in more resilient Failover Clusters. Dynamic Quorum Management takes the worry out of whether enough servers are active to achieve or maintain quorum if systems should fail or shut down. Multisite geoclusters also use weighted votes to specify which primary site should continue running in the event of intersite network failures.

Columnstore Indexes

Columnstore Indexes were bundled with Microsoft SQL Server 2012 borrowing on techniques originally developed for the PowerPivot in-memory store. Columnstore changes the way that rows are stored; instead of traditional row-by-row storage, data is stored one column at a time in a new layout that bunches up around a million column values in one large blob structure. This structure allows for incredible data compression.

A new method of processing Microsoft refers to as fast batch mode also speeds up query processing in SQL Server 2012. As Dr. David Dewitt explained at SQL Pass in 2010, the closeness of the successive columns values works well with the nature of modern CPUs by minimizing the data movement between levels of cache and the CPU.

There is, however, one big limitation to the current implementation of Columnstore Indexes. They are read-only, which means that the tables they index will also be read-only. Any table that has a Columnstore Index will not allow any inserts, updates or deletes. To change the data, the Columnstore Index has to be dropped, the necessary changes made and the Columnstore Index rebuilt. This isn’t the kind of operation that’s friendly to an online transaction processing (OLTP) system, which is what makes it solely a data warehousing, online analytical processing (OLAP) feature. It also puts a premium on partitioning on any table with a Columnstore Index. In the next major release of SQL Server, Microsoft is promising enhancements that lift the updatability restriction and also allow the Columnstore to be the clustered index.

I’ve had a chance to try out a Columnstore Index on a few tables. What I’ve found is that it works great when the nature of the query dovetails with the Columnstore. As a rule of thumb, the more columns in the table, the better the results. This is because SQL Server can avoid reading a large part of the index. In other situations, such as one narrow entity-attribute-value table that I work with frequently, the results are mixed. Summary queries that aggregate are much faster, to the tune of three seconds instead of 300, but queries that return all the columns of a small set of rows aren’t helped at all. I’ll be using Columnstore Indexes a lot looking for the 100 times speed improvements.

Hekaton

While Columnstore Indexes make data warehouse applications faster, Hekaton is intended for the other end of the application spectrum: high-volume OLTP systems. Websites, exchanges, manufacturing systems and order-entry systems that execute large numbers of, usually small, transactions are Hekaton’s target. The Hekaton extensions to SQL Server are what is known as an “in-memory” database, but Microsoft has combined several technologies to pump up transaction volume up to 50 times above what could previously be achieved. Hekaton will be included in the next release of SQL Server, which is not yet scheduled for shipment.

Hekaton starts with tables that are stored on disk but are pulled completely into system RAM.  This means will be limited to smaller tables or require a design that separates data with high activity from historical data. This requirement works well with the obvious server trend towards larger and larger amounts of RAM. It’s not uncommon to work with servers with 500 gigabytes or up to two terabytes of RAM. That’s plenty of room for the active data in most applications. The changes don’t stop with the approach to storage.

Code in a Hekaton system is written in good old T-SQL, just like we’ve used for years. But unlike traditional T-SQL, Hekaton code is compiled to native machine code and there’s no interpreter. T-SQL is great for data manipulation, but zipping through business logic isn’t one of its strengths; native compilation should speed things up significantly.

As servers have gained more cores, which are SQL Server’s mechanism for synchronizing data access, contention issues will arise as the system scales up. Hekaton bypasses these issues by implementing its own locking mechanism based on optimistic transactions that are optimized for an in-memory database. This allows many transactions to run simultaneously. However, the ability to mix Hekaton tables and other tables in structures such as a join may be limited. There will be other restrictions as well.

By combining the in-memory data handling, compiled code, and new concurrency control mechanism, the preliminary benchmarks for Hekaton look very promising. At SQL PASS 2012 I saw the development team demonstrate a 25-times throughput improvement in transaction volume. That’s 25 times– not just 25%. These are the kinds of surprising changes still in the cards for SQL Server. I’m looking forward to working with SQL Server more in the near future.

Another thing you may soon notice in Windows Server 2012 is the PowerShell and Server Manager Icons pinned to your taskbar. What you may not notice is that the default installation of the Windows Server 2012 operating system is now Server Core and contains more than 2,300 PowerShell cmdlets. Microsoft is sending a clear message that Windows servers should be managed just like any other data center server, both remotely and through the use of scripting. With Windows, that means PowerShell.

Fortunately, Windows Server Failover Clustering is no stranger to PowerShell. With Windows Server 2008 R2, 69 cluster-related PowerShell cmdlets assist with configuring clusters, groups and resources. This tip explores the new PowerShell cmdlets in Windows Server 2012 failover clusters.

With Windows Server 2012, a total of 81 failover cluster cmdlets can be used to manage components from PowerShell. New cluster cmdlets can perform cluster registry checkpoints for resources (Add-ClusterCheckpoint), monitor virtual machines for events or service failure (Add-ClusterVMMonitoredItem) and configure two new roles: Scale-Out File Servers (Add-ClusterScaleOutFileServerRole) and iSCSI Target Server (Add-ClusteriSCSITargetServerRole).
Windows PowerShell ISE

To list all the failover cluster cmdlets, use the PowerShell cmdlet “Get-command –module FailoverClusters” (Figure 1). I am using the built-in Windows PowerShell Integrated Scripting Environment (ISE) editor, which helps admins get familiar with all the failover clustering cmdlets.

In addition to the FailoverCluster cmdlets, Microsoft has several new modules of PowerShell cmdlets, including ClusterAwareUpdating with 17 new cmdlets, ClusterAware ScheduledTasks with 19 new cmdlets and iSCSITarget with 23 new cmdlets. There are many Cluster Aware Updating cmdlets, such as adding the CAU role (Add-CauClusterRole), getting an update report (Get-CauReport) or invoking a run to scan and install any new updates (Invoke-CauRun).

Cluster-Aware scheduled tasks are new to Windows Server 2012 and the Task Scheduler now integrates with failover clusters. A scheduled task can run in one of three ways:

ClusterWide on all cluster nodes
AnyNode on a random node in the cluster
ResourceSpecific on a node that owns a specific cluster resource

The new ScheduledTasks cmdlets create a cluster-aware scheduled task. In the table, you can see the cmdlets that register, get and set Clustered Scheduled task properties.
PowerShell Cmdlet     Description
Register-ClusteredScheduledTask     Creates a new clustered scheduled task
Unregister-ClusteredScheduledTask     Deletes a clustered scheduled task
Set-ClusteredScheduledTask     Updates existing cluster task
Get-ClusteredScheduleTask     Enumerates existing clustered tasks

To get an idea of how to use these PowerShell cmdlets, you first assign an action and trigger variable. The action variable specifies the program that is to be executed, such as the Windows calculator in the example below. The trigger variable sets up when the task is to be executed. The resulting cmdlets to schedule the task to run cluster-wide daily at 14:00 would look like this:

PS C:\> $action = New-ScheduledTaskAction –Execute C:\Windows\System32\Calc.exe

PS C:\> $trigger = New-ScheduledTaskTrigger -At 14:00 –Daily

PS C:\> Register-ClusteredScheduledTask -Action $action -TaskName ClusterWideCalculator -Description “Runs Calculator cluster wide” -TaskType ClusterWide -Trigger $trigger

TaskName         TaskType
——–         ——–
ClusterWideCa… ClusterWide

PS C:\>

While only PowerShell can be used to register, get/set and unregister Cluster-Aware scheduled tasks, you can use the Task Scheduler in Computer Management to view the cluster jobs (Figure 2).
iSCSI Target cmdlets

Finally, failover clusters can now be configured with a highly available iSCSI Target Server. This role allows you to create and serve iSCSI LUNs in a highly available fashion to clients across your enterprise. To add this new cluster role, use the Cmdlet Install-WindowsFeature –name FS-iSCSITarget-Server (or use Server Manager) to install the iSCSI Target Server role. Then, use the new cmdlet Add-ClusteriSCSITargetServerRole to create the iSCSI Target resource and associate it with shared storage. You can then leverage the new iSCSI Target cmdlets to configure iSCSI LUNs (Figure 3).

There is no shortage of PowerShell cmdlets in Windows Server 2012 to help you manage your failover clusters. In addition to creating, configuring and troubleshooting your cluster, you can use PowerShell cmdlets to add new scale-out file server, iSCSI Target Server roles, clustered scheduled tasks and Cluster-Aware Updating.

Be it for cloud scenarios or simple in-house setups, Windows Server 2012’s NIC teaming has a lot to offer in such a small package. It’s built right in and extremely simple to configure.

NIC teaming, or load balancing and failover, allows multiple NICs to be teamed together for bandwidth aggregation and failover in the event of a network hardware letdown. Until Windows Server 2012, we were at the mercy of NIC vendors to provide these features. There was no direct OS integration and Microsoft didn’t officially support NIC teaming. In Windows Server 2012, NIC teaming is front and center. It’s built right into the OS.

Some out-of-the-box NIC teaming features include:

• Support for virtual NICs inside Hyper-V
• Switch-dependent and switch-independent modes that do or do not require each NIC to be connected to the same Ethernet switch
• VLAN traffic division so that applications can communicate with different VLANs at once
• Support for up to 32 NICs per team

The only technologies that do not support NIC teaming in Windows Server 2012 are PCI I/O Virtualization, remote direct memory access and TCP Chimney, which are older technologies.

Configuring NIC teaming is a simple process that involves enabling it, adding a team on the server and configuring the specific network cards you wish to use for each team.

You can do this via PowerShell, the Server Manager GUI and via the RSAT tools in Windows 8. For PowerShell, you have a number of NIC teaming-specific commands such as:

• NetLbfoTeam (Get, New, Remove, Rename, Set)
• NetLbfoTeamMember (Add, Get, Remove, Set)
• NetlbfoTeamNic (Get, New , Remove, Set)

Simply entering Get-Command -Module NetLbfo will show you all the commands available.

In the GUI, configuring a NIC team is a matter of:

1. Selecting Local Server/Properties/Remote Desktop/NIC Teaming Administration.
2. Selecting the server name and under Teams/Tasks, selecting New Team.
3. Entering your team name and selecting the specific network adapters you want to use for the team.

More details about NIC teaming can be found in Microsoft’s document Windows Server 2012 NIC Teaming (LBFO) Deployment and Management.

One thing I’ve witnessed over the years is network admins not taking advantage of IT management and security controls they already have at their disposal. Having been in network administrator shoes, I think this is due in large part to a general lack of time and focus.  NIC teaming is not all that sexy, but it can buy you a ton of server resiliency. Customers, internal auditors and even management will never know you’re using it, but that’s what IT is about anyway: making things look simple by keeping the shop running smoothly. Microsoft is throwing us a bone with NIC teaming. I can’t think of any reason to not take advantage of it in Windows Server 2012.

But Microsoft reintroduced the DirectAccess feature with Windows 8. In doing so, they made setup of DirectAccess much easier, and organizations might do well to take a fresh look at DirectAccess.

For those not be familiar with DirectAccess, it is a solution designed to provide mobile users with connectivity to the corporate network. Unlike a VPN, the end user does not have to do anything to initiate the connection. If the user has an Internet connection, they are automatically connected to the corporate network.

DirectAccess offers benefits beyond simplifying the end-user experience. One of the problems that has long plagued IT pros is that of managing remote computers. Laptops need to be updated and backed up just like any other computer. The problem is that mobile users spend a lot of time outside of the office, which makes it difficult for the IT department to perform maintenance on mobile user’s laptops. As a result, many IT pros write elaborate scripts to apply patches or run backups whenever remote users connect to a VPN.

The problem with this approach is that users are often connected to VPNs for relatively short amounts of time. The duration of the user’s session might be inadequate for performing all of the necessary maintenance. DirectAccess can help with this problem because the user is connected to the corporate network any time they have Internet connectivity. Since the amount of time a user’s computer is connected to the Internet is often much longer than the amount of time that the user spends logged into a VPN, automated maintenance tasks are more likely to be completed.

The prerequisites that your DirectAccess server must meet are relatively modest. The server must be joined to a domain, and it must have at least one network adapter that has been configured with a static IP address.

Deploying DirectAccess

As previously mentioned, DirectAccess is much easier to deploy and configure in Windows Server 2012 than it was in Windows Server 2008 R2. The first step in deploying DirectAccess is to install the Remote Access Role through the Server Manager’s Add Roles and Features Wizard (Figure Above).

fter selecting the Remote Access role, click Next three times and you will see a screen asking you which Remote Access role services you want to install. Choose the DirectAccess and VPN (RAS) role services and then complete the Add Roles and Features Wizard by accepting the defaults.

When the Remote Access role and the corresponding role features finish installing, the Server Manager will display a warning icon. Clicking this icon reveals a message indicating that there are post-deployment configuration tasks that must be performed. Click on the Open the Getting Started Wizard link, found in the warning message.

At this point, Windows will launch the Configure Remote Access wizard. Click the Deploy DirectAccess Only link.

After a quick prerequisite check, the wizard will ask you to specify your network topology. The DirectAccess Server can act as an edge device, or it can reside behind an edge device. If you choose to place the DirectAccess Server behind an edge device (such as a NAT firewall), you will need to specify whether the DirectAccess server uses a single NIC or two separate NICs.

After specifying your edge topology, you must enter either the IP address or the fully qualified domain name that clients will use when they connect to the DirectAccess server (figure 5).

Click Finish to complete the wizard. Upon doing so, Windows will display the Remote Access Management Console, which you can use to monitor your DirectAccess Server (figure 6).

Client Requirements

Unfortunately, Windows 8 is the only desktop operating system that is natively compatible with Windows Server 2012′s DirectAccess feature.

Even at that, there are some additional requirements that must be met. Client computers must be equipped with a TPM chip and users will need either a physical or a virtual smart card.

The good news is that Microsoft now supports accessing Windows Server 2012 servers from Windows 7 clients as well. To do so, Windows 7 clients must have version 2.0 of the Microsoft DirectAccess Connectivity Assistant installed, available for download here.

The Windows Server 2012 version of DirectAccess is much easier to deploy and configure than the previous version. DirectAccess’ simplicity and its automated connectivity make it plausible as a VPN replacement.

 Identifying networking cmdlets

In Windows Server 2012, there are now hundreds of Windows PowerShell cmdlets that can be used to view, configure, and monitor different networking components and services in the platform. The tasks you can perform using these cmdlets range from the common (such as configuring static IP addresses or DHCP reservations for servers) to more specialized (such as configuring quality-of-service parameters) to settings related to virtual environments (such as configuring the Hyper-V extensible switch). There is obviously too much to learn here in a single lesson or even a single book, and some tasks might be performed only occasionally or even not at all by many administrators. So let’s begin with a more practical approach to the problem of administering a Windows Server 2012 networking environment using Windows PowerShell by asking a simple question: How can you find the right cmdlet (if there is a cmdlet) to perform a particular networking task?

Using Get-Command

You could start by using the Get-Command cmdlet to search for all Windows PowerShell cmdlets and functions that have the string “net” in their names.This generates a lot of output, however, as shown here:

PS C:\> Get-Command *net*
CommandType Name ModuleName
----------- ---- ----------
Function Add-NetIPHttpsCertBinding NetworkTransition
Function Add-NetLbfoTeamMember NetLbfo
Function Add-NetLbfoTeamNic NetLbfo
Function Add-NetSwitchTeamMember NetSwitchTeam
Function Copy-NetFirewallRule NetSecurity
Function Copy-NetIPsecMainModeCryptoSet NetSecurity
Function Copy-NetIPsecMainModeRule NetSecurity
Function Copy-NetIPsecPhase1AuthSet NetSecurity
Function Copy-NetIPsecPhase2AuthSet NetSecurity
Function Copy-NetIPsecQuickModeCryptoSet NetSecurity
Function Copy-NetIPsecRule NetSecurity
Function Disable-NetAdapter NetAdapter
Function Disable-NetAdapterBinding NetAdapter
Function Disable-NetAdapterChecksumOffload NetAdapter
Function Disable-NetAdapterEncapsulatedPacketTaskOffload NetAdapter
Function Disable-NetAdapterIPsecOffload NetAdapter
...
From the preceding output, you can see there are several Windows PowerShell modules that perform network-related actions.To see this more clearly, the following commands take the preceding output, sort it by module name, and remove duplicates:

PS C:\> Get-Command *net* | Sort-Object ModuleName | Format-Table ModuleName `
-HideTableHeaders | Out-String | Out-File c:\data\test.txt
PS C:\> Get-Content C:\data\test.txt | Get-Unique
ActiveDirectory
BranchCache
DnsServer
MsDtc
NetAdapter
NetConnection
NetLbfo
NetQos
NetSecurity
NetSwitchTeam
NetTCPIP
NetworkTransition
NFS
SmbShare
To investigate the NetTCPIP module further, you can use the –Module parameter of Get-Command to list all cmdlets and functions contained in this module:
PS C:\> Get-Command -Module NetTCPIP | Sort-Object Name | Format-Table Name
Name
----
Get-NetIPAddress
Get-NetIPConfiguration
Get-NetIPInterface
Get-NetIPv4Protocol
Get-NetIPv6Protocol
Get-NetNeighbor
Get-NetOffloadGlobalSetting
Get-NetPrefixPolicy
Get-NetRoute
Get-NetTCPConnection
Get-NetTCPSetting
Get-NetTransportFilter
Get-NetUDPEndpoint
Get-NetUDPSetting
New-NetIPAddress
New-NetNeighbor
New-NetRoute
New-NetTransportFilter
Remove-NetIPAddress
Remove-NetNeighbor
Remove-NetRoute
Remove-NetTransportFilter
Set-NetIPAddress
Set-NetIPInterface
Set-NetIPv4Protocol
Set-NetIPv6Protocol
Set-NetNeighbor
Set-NetOffloadGlobalSetting
Set-NetRoute
Set-NetTCPSetting
Set-NetUDPSetting

Using Show-Command

At this point, you can begin using Get-Help to learn about the syntax of NetTCPIP cmdlets you’re interested in and to see some examples of their usage.Unfortunately for administrators who are not that familiar with Windows PowerShell, the syntax displayed when you use Get-Help with a cmdlet can appear daunting.For example, consider a scenario where you have a web server running Windows Server 2012 and you want to add a second IP address to a network adapter on the server.

You might guess from the output of Show-Command –Module NetTCPIP shown previously that New-NetIPAddress is the cmdlet you use to perform this task, and you would be correct. But to the Windows PowerShell beginner, the syntax from Get-Help New-NetIPAddress might look quite confusing:

Parameter Set: ByInterfaceAlias
New-NetIPAddress -InterfaceAlias [-AddressFamily ] [-AsJob]
[-CimSession <CimSession[]> ] [-DefaultGateway ] [-IPv4Address ]
[-IPv6Address ] [-PassThru] [-PreferredLifetime ]
[-PrefixLength ] [-PrefixOrigin ] [-SkipAsSource ]
[-Store ] [-SuffixOrigin ] [-ThrottleLimit ]
[-Type ] [-ValidLifetime ] [-Confirm] [-WhatIf] [ ]
Parameter Set: ByIfIndexOrIfAlias
New-NetIPAddress [-AddressFamily ] [-AsJob]
[-CimSession <CimSession[]> ] [-DefaultGateway ] [-InterfaceAlias ]
[-InterfaceIndex ] [-IPv4Address ] [-IPv6Address ]
[-PassThru] [-PreferredLifetime ] [-PrefixLength ]
[-PrefixOrigin ] [-SkipAsSource ] [-Store ]
[-SuffixOrigin ] [-ThrottleLimit ] [-Type ]
[-ValidLifetime ] [-Confirm] [-WhatIf] [<CommonParameters>]

Fortunately, the new Show-Command cmdlet in Windows Server 2012 can help make the syntax of Windows PowerShell cmdlets easier to understand and use. Start typing the following command:

Show-Command New-NetIPAddress

When you run the preceding command, the properties page shown in Figure 6-6 opens to show you the different parameters you can use with the New-NetIPAddress cmdlet. Parameters such as InterfaceAlias and IPAddress that are marked with an asterisk are mandatory; those not marked this way are optional.

Clearly, to add a new IP address you first need to know the alias or index of the network interface to which you want to add the address. To find the interfaces on the system, you could use Get-Command *interface* to find all cmdlets that include “interface” in their name. Of the eight cmdlets displayed when you run this command, the cmdlet Get-NetIPAddress is the one you are looking for, and running this cmdlet displays a list of all interfaces on the server:

Get-NetIPInterface
ifIndex InterfaceAlias AddressFamily NlMtu(Bytes) InterfaceMetric Dhcp
------- -------------- ------------- ------------ --------------- ----
12 Ethernet IPv6 1500 5 Disabled
14 Teredo Tunneling Pseudo... IPv6 1280 50 Disabled
13 isatap.{4B8DC8AE-DE20-4... IPv6 1280 50 Disabled
1 Loopback Pseudo-Interfa. IPv6 4294967295 50 Disabled
12 Ethernet IPv4 1500 5 Disabled
1 Loopback Pseudo-Interfa. IPv4 4294967295 50 Disabled

From the preceding command output, you can see that the interface you are looking for is identified by the alias “Ethernet.” To view the existing TCP/IP configuration of this interface, you can use the –InterfaceAlias with the Get-NetIPAddress cmdlet as follows:

 Get-NetIPAddress -InterfaceAlias Ethernet
IPAddress : fe80::cf8:11a1:2e3:d9bc%12
InterfaceIndex : 12
InterfaceAlias : Ethernet
AddressFamily : IPv6
Type : Unicast
PrefixLength : 64
PrefixOrigin : WellKnown
SuffixOrigin : Link
AddressState : Preferred
ValidLifetime : Infinite ([TimeSpan]::MaxValue)
PreferredLifetime : Infinite ([TimeSpan]::MaxValue)
SkipAsSource : False
PolicyStore : ActiveStore
IPAddress : 172.16.11.236
InterfaceIndex : 12
InterfaceAlias : Ethernet
AddressFamily : IPv4
Type : Unicast
PrefixLength : 24
PrefixOrigin : Manual
SuffixOrigin : Manual
AddressState : Preferred
ValidLifetime : Infinite ([TimeSpan]::MaxValue)
PreferredLifetime : Infinite ([TimeSpan]::MaxValue)
SkipAsSource : False
PolicyStore : ActiveStore

The preceding command output shows that the Ethernet interface currently has 172.16.11.236/24 as its IPv4 address and Classless Inter-Domain Routing (CIDR) prefix.

Returning to the open properties page displayed by Show-Command New-NetIPAddress, you can add a second IP address to the interface by specifying the parameter values.

If you click Copy in the properties page shown in Figure 6-7, the command is copied to the clipboard. The resulting command looks like this:

New-NetIPAddress -InterfaceAlias Ethernet -IPAddress 172.16.11.237 `

-AddressFamily IPv4 -PrefixLength 24

If you click Run, the command executes. By using –InterfaceAlias with the

Get-NetIPAddress cmdlet again, you can verify that the command accomplished the desired result:

Get-NetIPAddress -InterfaceAlias Ethernet
IPAddress : fe80::cf8:11a1:2e3:d9bc%12
InterfaceIndex : 12
InterfaceAlias : Ethernet
AddressFamily : IPv6
Type : Unicast
PrefixLength : 64
PrefixOrigin : WellKnown
SuffixOrigin : Link
AddressState : Preferred
ValidLifetime : Infinite ([TimeSpan]::MaxValue)
PreferredLifetime : Infinite ([TimeSpan]::MaxValue)
SkipAsSource : False
PolicyStore : ActiveStore
IPAddress : 172.16.11.237
InterfaceIndex : 12
InterfaceAlias : Ethernet
AddressFamily : IPv4
Type : Unicast
PrefixLength : 24
PrefixOrigin : Manual
SuffixOrigin : Manual
AddressState : Preferred
ValidLifetime : Infinite ([TimeSpan]::MaxValue)
PreferredLifetime : Infinite ([TimeSpan]::MaxValue)
SkipAsSource : False
PolicyStore : ActiveStore
IPAddress : 172.16.11.236
InterfaceIndex : 12
InterfaceAlias : Ethernet
AddressFamily : IPv4
Type : Unicast
PrefixLength : 24
PrefixOrigin : Manual
SuffixOrigin : Manual
AddressState : Preferred
ValidLifetime : Infinite ([TimeSpan]::MaxValue)
PreferredLifetime : Infinite ([TimeSpan]::MaxValue)
SkipAsSource : False
PolicyStore : ActiveStore

Conclusion

The best way to learn how to use Windows PowerShell to administer network settings and services on Windows Server 2012 is to experiment with performing different tasks in a test environment.

• Single Site Windows Server Failover Clustering
• Multi-Site Windows Server Failover Clustering
• San level Block Replication
• Transaction Log Shipping
• Database Mirroring
• Transactional Replication
• Peer-to-Peer Replication

Some of these can take time and resources to implement, and may therefore not be meeting your current requirements. This is where SQL Server 2012 AlwaysOn can help, because it provides the benefits of:

• Using the WSFC APIs to perform failovers. Shared storage is not required
• Utilizing database mirroring for the data transfer over TCP/IP
• providing a combination of Synchronous and Asynchronous mirroring
• providing a logical grouping of similar databases via Availability Groups
• Creating up to four readable secondary replicas
• Allowing backups to be undertaken on a secondary replica
• Performing DBCC statements against a secondary replica
• Employing Built-in Compression & Encryption

I’ll need to explain some of these components of AlwaysOn

Windows Server Failover Clustering (WSFC)

Clustering technology has been around for quite some time, starting with Microsoft Clustering Services (MCS) back in NT 4.0 days.. The technology for WSFC is part of the backbone of AlwaysOn. A WSFC cluster is a group of independent servers that work together to increase the availability of applications and services. It does this by monitoring the health of the active node and failing over to a backup node, with automatic transfer of resource ownership, when problems are detected.

Although the WSFC is able to span multiple subnets, a SQL Server which is cluster-aware has not, until now, been able to support a clustered instance of SQL Server across multiple subnets: It has therefore been quite expensive to set up clustering across multiple data centres due to the WSFC requiring shared storage in both data centres as well as the block level SAN replication. This has required a lot of work with your storage vendors to get your setup correct.

AlwaysOn Nodes

The nodes that you will use in your SQL Server 2012 AlwaysOn solution have to be part of a WSFC. The first step we need to undertake in preparing our AlwaysOn nodes is to add the Failover Cluster Feature to each node. I’ll go into detail later on in this article.

AlwaysOn Storage

SQL Server versions prior to SQL Server 2012, being setup as clustered instance on a WSFC require the storage to be presented as shared storage. This requirement leads to the storage being more expensive and a little bit more complicated to configure and administer. With SQL Server 2012 AlwaysOn your solution does not have to utilise shared storage, but can use SAN, DAS, NAS or Local Disk depending on your budget and requirements. I suggest working with your storage providers to come up with the solution you need.

Availability Groups

SQL Server 2012 AlwaysOn allows for the more granular control of your environment with the introduction of AlwaysOn Availability Groups (AAG’s). AAG’s allow you to configure groups of databases that you would like to failover all together when there is a problem with the host server. When configuring your AAG’s you:

• Configure your AAG on the Primary Replica (Your AAG contains the group of DBs that you wish to group together to failover to your secondary replicas)
• You will need to configure between one and four secondary replicas, with any combination of Synchronous (Maximum of two) and Asynchronous Mirroring (Your primary replica is available for read and write connectivity, while your secondary replicas can be configured for read-only, read intent or no access)

Maintenance Tasks/ Reporting

AlwaysOnallows you to use the secondary replicas that you would have created when you setup your AAGs to undertake some regular database maintenance tasks to remove some of the performance overheads from your primary production server. Some of the tasks that you could look at undertaking on a secondary replica are:

• Database Backups
  • Full Backup With Copy_Only
  • Transaction Log Backups
• DBCC CheckDB
• Reporting
• Database Snapshots

Security & Performance

To give you the full benefits of high availability, there will be a lot of movement of data. This brings with it security risks and higher bandwidth demands. To minimise these requirements Transparent Database Encryption (TDE) as well as Backup Compression, are both shipped with the Enterprise Edition,

Implementing AlwaysOn

Now that we have covered off the basics of what an AlwaysOn solution could possibly look like we are ready to start and plan for implementing this solution to meet your ever increasing High-Availability requirements and DR needs.

Building your AlwaysOn Cluster

In this scenario we are going to build a two-node SQL Server 2012 AlwaysOn Cluster. To achieve this, all of the nodes that are going to participate in the SQL Server AlwaysOn Cluster need to have .NET Framework 3.5.1 and the Failover Clustering feature enabled.

Required features for Failover Cluster

Now that we have enabled both of these features we can build our WSFC. From the Control Panel | Administrative Tools | Failover Cluster Manager | Validate a Configuration, we can validate whether our servers are okay to participate in a WSFC.

Validate Failover Cluster

Building your Windows Server Failover Cluster

There is no difference between the task of building your WSFC for use with SQL Server 2012 AlwaysOn and your previously built WSFC for SQL Server 2008 R2. If you have never built a WSFC before, you can read more on this here Failover Cluster Step-By-Step Guide. In this article, I am not going to go through the WSFC build, but I need to mention that your WSFC build needs to pass all of the validation rules in order to give you a supported WSFC.

SQL Server 2012 Setup

Now that we have our two nodes in our WSFC, we are ready to start the build process for our SQL Server 2012 AlwaysOn Cluster. We need to make sure that we have our installation media which is available for download from Microsoft SQL Server 2012 Downloads.

On Node1, we start the setup.exe to begin the installation process. We are greeted with the initial screen. You should navigate to the Installation Tab to start the installation, selecting ‘New SQL Server stand-alone installation or add features to an existing installation’.

Stand-Alone Installation

Enter your product key, click ‘Next’.

Enter Product Key

Accept the Terms and Conditions, click ‘Next’.

Ensure you select ‘SQL Server Feature Installation’, click ‘Next’.

SQL Server Feature Installation

Choose the features you need to install, click ‘Next’.

Recomended SQL Server Features

our installation rules will be checked and, as long as there are no issues, you can continue with the installation by clicking ‘Next’.

Enter your SQL Server 2012 Instance Name for the Instance that you are building, click ‘Next’.

Type your Instance Name

Normally I would recommend having different service accounts for each of the SQL Services that you are installing. However, in this installation I am just using the default local accounts. You will need to have your Domain service accounts created and set the passwords on this Server Configuration screen in the installation. Once you have set the passwords, make sure you click on the Collation Tab so as to configure your Collation for the Instance, click ‘Next’.

Service Account Detail

On the Database Engine Configuration screen there are three tabs that we need to pay attention to. The Server Configuration Tab is where you set your security mode – Either Windows (recommended) or Mixed Mode. Remember to add the current account you are running the installation as, as well as any other individuals or groups that need to be members of the SysAdmins group.

The Data Directories Tab allows you to specify where you want to have your User Databases, TempDB and backup locations to be stored. Traditionally you would have four separate drive locations depending on your storage for Data files, Log Files, TempDB and Backups.

The FileStream Tab allows you to Enable Filestream if this is a required option that you need in your environment.

Click ‘Next’ until you get to the ‘Ready to Install’ screen. At this point in time you should review what is going to be installed and, if you are happy, then Click the Install button.

Click ‘Next’ until you get to the ‘Ready to Install’ screen. At this point in time you should review what is going to be installed and, if you are happy, then Click the Install button.

Remember that these same steps need to be completed on the second node that you are including into your SQL Server 2012 AlwaysOn Cluster.

Configuring SQL Server 2012

Now that we have installed two stand-alone instances of SQL Server 2012 on our two servers in the WSFC we need to undertake some post-installation configuration. This is achieved by using the SQL Server Configuration Manager which is available from Start | All Programs | Microsoft SQL Server 2012 | Configuration Tools.

Because the data transfers by SQL Server 2012 AlwaysOn are done via TCP/IP we need to enable this in the Network Configuration Protocols. By default this will be disabled. Change the value to Enabled and click ‘OK’.

We are now at the main point with configuring our SQL Server 2012 AlwaysOn Cluster. Previously, we were creating a Clustered SQL Server Instance and we had to undertake the Clustered Build Option. You will have noticed that we have installed stand-alone instances of SQL Server on each of the nodes participating in the WSFC. We need to enable AlwaysOn Availability Groups. In the ‘SQL Server Configuration Manager’ select the Instance of SQL Server, right click, Select Properties. On the ‘AlwaysOn High Availability’ Tab tick the ‘Enable AlwaysOn Availability Groups’ check box.

Click ‘OK’. The changes will not take effect until the Instance is restarted. You will need to repeat this step on the second instance we installed. (This will need to be done on every instance in your SQL Server 2012 AlwaysOn Cluster)

Enable AlwaysOn Availability Groups

We are now ready to start configuring our Availability Groups.

Configuring SQL Server 2012 AlwaysOn Availability Groups

Before SQL Server 2012, one of the options available for you to use to build your High Availability (HA) solution was to utilise Database Mirroring. The Database Mirroring technology is very good at what it was created for. However, it has some limitations when it comes to your HA solution. The limitations include:

• A Single Secondary database
• Mirrored database is accessible via db snapshot only until failover occurs
• Lack of support for MSDTC (distributed transactions)
• Related databases are not able to be grouped together

SQL Server 2012 AAG’s resolve most of these issues giving you more flexibility over your environment and more granular control over your environment to meet your ever growing complex HA requirements.

With implementing SQL Server 2012 AAG’s, which is still utilising the Database Mirroring technology to transfer your data via TCP/IP either synchronously or asynchronously to one or more replicas but giving you the added advantage of being able to access these replicas. It still does not support transactional consistency for those databases participating in a availability group.

Availability Groups

As its name suggests, an Availability Group is a grouping of related databases. When you were setting up Database Mirroring Before SQL Server 2012, you could set up multiple mirrors, but you were only able to set up to mirror a single database at a time. If you have multiple databases that are reliant on each other for the application to work, there is no simple way of ensuring that all of the databases failed over together. Availability Groups now allow you to group appropriate databases together. You can setup, up to 10 AAG’s on a per instance level. Across these 10 Availability Groups you can have up to 100 replica databases participating.

The benefits given by an Availability Group are that it:

• Supports Alternative Availability Modes
• Supports Multiple forms of AAG Failover
• Supports Configuring Secondary Replicas in Read-Only Mode
• Supports Configuring Secondary Replicas to perform Backups
• Supports Automatic Page Repair
• Supports Encryption and Compression
• Supports Management via
  • TSQL
  • Powershell
  • GUI Wizards
  • Dashboard
  • Management Studio
• Fast application Failover through the use of AlwaysOn Availability Group Listeners (AAGLs)

Availability Replicas

Availability replicas provide you the ability to setup:

• A primary replica which allows you to undertake read and write capabilities against those databases that have been configured in the AAG
• Up to four secondary replicas which allow you to have read-only capabilities against those databases that have been configured in the AAG. Also allows you to setup the ability to perform backups on these secondaries.

Availability Modes

As mentioned above, when configuring your SQL Server 2012 AlwaysOn Availability Groups, there are some considerations that need to be taken into account when determining what type of availability mode you can use.

If you are wanting to use AAGs for a reporting process, you could have your secondary replica located in the same physical data centre and implement synchronous-commit mode to give you a read only near time group of databases to report against without impacting the performance of the primary databases with reporting overheads. You probably would not consider this type of availability mode where there are large distances between data centres.

If you have the requirement for a reporting process, that does not require the data to be near real time, you could consider implementing your secondary replica in a separate data centre that may be more than 30-40 Kilometers away. If this is the case, you would look at implementing asynchronous-commits for your AAG. By implementing an asynchronous-commit method, you would reduce the latency of the transactions on the primary site but it would open you up to the possibility of data loss.

As you can set up several secondary replicas, you are able to setup different availability modes in your environment. Each AAG is configured separately; for example: you may have two synchronous implementations and two asynchronous implementations.

In this example you would have your primary databases in AAG1 residing in DC1. You then set up a secondary replica that is also located in DC1 in a synchronous-commit mode, thereby allowing you to run your reporting requirements without the reporting overhead impacting on your primary database. This also provides for your HA requirements, by having a secondary environment that is transactionally consistent with the ability to failover to in the event of an issue with your primary databases. You could then setup secondary replicas in DC2, DC3 & DC4 in asynchronous-commit mode. These asynchronous secondary replicas allow you to meet your DR requirements by having multiple copies in multiple geographical dispersed locations, with the ability to failover to in the event of an issue on the primary site.

Failing Over

As with Database Mirroring and Windows Server Failover Clustering, AlwaysOn Availability Groups provide the ability to failover between the primary and secondary replicas that you have setup. There are three forms of failover which can be undertaken with AAG’s:

• Automatic - Supported by Synchronous-Commit Mode – No Data Loss
• Manual - Supported by Synchronous-Commit Mode – No Data Loss
• Forced – Supported by Asynchronous-Commit – Possible Data Loss

The Availability Mode that is in use will depend on whether you are implementing High Availability or Disaster Recovery. This affects the failover setup that you are going to implement in your SQL Server 2012 AlwaysOn environment.

Availability Group Listener

In order to take advantage of the various solutions that we have stepped through in this article, we need to set up and allow for the applications to maintain connectivity to the SQL Server Databases after a failover. This is where the AlwaysOn Availability Group Listeners (AAGL’s) come into use.

An Availability Group Listener is a Virtual Server Name that applications connect to. From the applications point of view it does not matter where the Availability Database is active and available for use. The AAGL consists of:

• Virtual Network Name (VNN)
• Listener Port
• One or more Virtual IP Addresses (VIPs)

For your application to connect, you can either set up a connection string for your AAGL or connect directly to your SQL Server Instance. However, a direct connection does not give the failover support which this technology has been built for.

When a failover occurs for an AAG, the connection from the client is terminated. To gain access again, the client needs to reconnect to the AAGL. To achieve this, the application must be designed and built to poll for the AAGL. Depending on the connection that you are utilising:

• Primary database
• Secondary read replica

You will need to configure your ‘ApplicationIntent‘ in your AAGL connection string appropriately.

With these points in mind, we are now able to create our first AAG in several ways, which are to

• Create Availability Group Wizard
• TSQL
• Powershell

Expanding the AlwaysOn High Availability tree | right click Availability Groups | New Availability Group Wizard

New AlwaysOn Availability Group Wizard

Name your AAG, click ‘Next’.

Name your AlwaysOn Availability Group

Select the databases that you need to include in the AAG, click ‘Next’.

Availability Databases

Your primary replica will automatically be available for you to configure. Choose the Availability Mode, Failover strategy and Readable secondary requirements. Click ‘Add Replica’, connecting to your appropriate secondary servers. Ensure that you set your secondary the same as your primary.

Availability Databases

Selecting the Listener Tab, give your AAGL a name, port number and the appropriate IP Addresses, click ‘Next’.

Every replica needs to have access to a shared location to access the database backups created and used for synchronising the secondary databases. Enter your share path, click ‘Next’.

Initial Data Synchronization

Ensure that you receive all green ticks for your validation, click ‘Next’.

Review the summary, click ‘Finish’.

My design has been done in lab. If want to know how to build a lab please visit my friend blog post.

Enjoy configuring your new SQL Server 2012 AlwaysOn environment.