News

SQL Server AlwaysOn Support Coming to Windows Azure

• By Kurt Mackie
• 08/13/2013

In an announcement made on Monday, Microsoft announced five Windows Azure improvements, including support for SQL Server AlwaysOn.

Most of the improvements to Microsoft's cloud-based Windows Azure are at the "general availability" stage, signifying final product release. The one exception is AutoScale support for Windows Azure, which is at the preview test stage.

All five Windows Azure improvements are currently available for use, according to Microsoft's announcement. Microsoft added improvements to configuring load balancers in Windows Azure virtual machines (VMs). It moved some alerts into the Windows Azure management portal. And it threw in some perks for developers that use Microsoft's Windows Azure-based push technology for mobile apps.

SQL Server AlwaysOn
Perhaps, the most notable improvement in the mix is the integration of SQL Server AlwaysOn availability groups in Windows Azure Infrastructure Services for disaster recovery and high availability support. AlwaysOn availability groups is a SQL Server 2012 technology that allows groups of databases to be failed over to other SQL Server installations. It can enable disaster recovery scenarios while also avoiding architectures that have single points of failure, as in some server cluster failover scenarios, according to a description by Microsoft MVP Brien Posey.

Microsoft has now delivered its SQL Server AlwaysOn technology to support VMs running in Windows Azure. The technology works with SQL Server 2012 and SQL Server 2014, although SQL Server 2014 is currently at the community technology preview stage. Multiple database failovers are supported, with up to five for SQL Server 2012 and up to nine for the future SQL Server 2014 product, according to Microsoft's announcement.

With the integrated AlwaysOn technology in Windows Azure, it's possible to create one or more "readable secondary replicas," which Microsoft suggests can be used to offload business intelligence applications or reporting, in addition to supporting disaster recovery scenarios. The secondaries can run in the cloud, adding disaster recovery capabilities to a premises-based SQL Server implementation.

Before this general availability release, the SQL Server AlwaysOn availability group technology had restrictions on replica support for Windows Azure VMs, according to the SQL Server team.

"Until now, client applications wanting to connect to the primary replica of an availability group on Windows Azure Infrastructure Services only had the option of specifying a Failover Partner (similar to Database Mirroring). This restricted the configuration of availability groups to only two replicas (one primary and one secondary) and these couldn't be configured as readable when acting as secondaries. The new support for Availability Group Listeners removes this limitation," according to a Microsoft blog post.

AutoScale
Microsoft's AutoScale is designed to scale applications running on Windows Azure automatically, based on preconfigured criteria. It can be set to respond to application load, spinning up more application instances. With this general release, AutoScale now supports schedule rules configurations. It can be set according to different times (day and night), CPU activity or queue depth. Microsoft also beefed up some reporting associated with scale-up or scale-down actions, which now appears in the Windows Azure Management Portal.

The new AutoScale capability only applies to Windows Azure services at present, but Microsoft is planning an expansion.

"Today’s release only supports Scheduled AutoScale rules on Cloud Services -- but you'll see us enable these with all types of compute resources (including Web Sites, Mobile Services + VMs) shortly," Microsoft's announcement states.

Load Balancer VM Support
Microsoft has added the ability to configure HTTP probes for VM load balancer support. Load balancing is offered as part of Windows Azure services at no extra cost. The load balancer service uses probes to check for VM failures, and, if found, an automatic failover procedure starts up.

The new HTTP probes configuration capability in Windows Azure allows probes to be sent to "a separate network port than the one you are load-balancing," according to Microsoft's description. It's an "advanced option" to the old TCP probe approach, although IT pros can opt to use either TCP or HTTP network probe settings. Using HTTP probes adds "a lot more control over traffic being delivered to your service," according to Microsoft.

In addition, this general availability release allows the use of the Windows Azure Management Portal to configure the probe's management settings. Doing that used to require using either Microsoft's Cross-Platform CLI tools, PowerShell or writing code for the REST-based API, according to the announcement. The Windows Azure Management Portal now will show when probe setting are misconfigured.

Management Services
Microsoft added a "management services" extension to the Windows Azure Management Portal. This management services tab in the portal will show alerts and operation log information that previously were tucked away in the "settings" extension.

Reporting in the operations logs also has been extended. The logs now show alerts, AutoScale changes, disk operations and SQL backup changes, in addition to storage and cloud services histories.

Notification Hubs
Lastly, independent software developers can now deliver push notifications to their applications on mobile devices using Microsoft's "notification hubs" technology. The technology supports Windows Store apps, Windows Phone 8, Android and iOS platforms. It can push notifications to millions of devices per day. The technology works with Microsoft's Windows Azure Mobile Services, apps hosted on Windows Azure VMs, Web sites or cloud services.

The notification hubs technology is designed to manage backend operations, such as device tokens and URIs that are used for push notifications, according to Microsoft. With this release, Microsoft added the ability to track 50 different factors associated with push notifications.

Developers can use .NET or Node.js software development kits or REST-based APIs. The Bing News App on Windows and Windows Phone devices is currently using notifications hubs to alert users of news stories, based on topics of interest, Microsoft indicated.

Microsoft plans to charge for its notification hubs technology after Sept. 30, 2013, offering Basic and Standard plans. A free offering also will be available that supports "100,000 notifications with 500 registered devices each month."