Implement Virtualization for Application High-Availability

Alone, the term ‘high availability‘ does not mean your application never goes down, that would be ‘always on‘, but highly available applications require some simple things you might already have within your infrastructure. If you run a virtual environment, then achieving application high availability is just a few clicks or scripts away, if you choose to roll-your-own, but there are also products that one can purchase to do similar things such as Symantec’s Application HA package, a scaled down version of Veritas Cluster Server. But if what you need is “protection right now, today” then you can get started by using built-in technologies for a given hypervisor.

HA Process

Regardless of type of hypervisor you can enable guest failover, moving, takeover, replication, etc and can be done through a series of different steps and mostly involves mild scripting.

For all VM hosts there is some kind of scripting hook that can be used to achieve the following series of steps:

  1. Verify whether or not the Guest VM is on-line and booted
  2. Verify VM related settings and store/export them if needed
  3. Control the VM (quiesce, freeze, power-off, shutdown, etc) to prepare for movement
  4. Backup or copy the VM to new storage or a new host
  5. Restore VM related settings/import them if needed
  6. Spin up the VM
  7. Verify whether or not the Guest VM is on-line, booted, and active on the new host or location

These are the basic steps that can be achieved through scripting either by utilizing APIs for each hypervisor or manually performing each and every step through the use of standard OS level scripting automation. (logging in as a user, executing a power off or other set of commands to prepare the VM and logging in after the VM has been powered on again to validate it is up and running properly and start applications)

Developing this type of capability can be pretty easy but does take some time so be aware of any tools you might need but simply because the VMs exist in containers able to be moved pretty much anywhere on the same network segment or route, that is all that is required so long as the guest VM can run on the target platform. You of course may need to integrate your host monitoring software in order to execute the scripts automatically, but if you don’t have that level of monitoring in your environment you can script that too and all with assets you already own. The main investment is time and testing to ensure the environment is sound after a move/failover.

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Microsoft Windows Server 2012 Hyper-V Changes

Microsoft’s recent release of Windows Server has cutting edge changes to Hyper-V which will finally give Microsoft more confidence about espousing the virtues of Hyper-V and provide sales fodder for making a case against virtualizing with VMware. Microsoft Hyper-V has been completely rewritten in this new version of Windows Server and allows for things like simplified Live Migration, templating, multi-tenancy and deduplication technology just to name a few. Evidence of this first came out when Microsoft started publishing comparison documents showing these vast improvements between it’s own Windows Server 2008 R2 (at the time a huge improvement in Hyper-V in its own right) and the yet to be released upgrade Windows Server 2012.  This document, Windows Server Comparison, is a great example of how seriously Microsoft took its renewed fervor.

From the PDF for example:

Microsoft Hyper-V 2012 PDF Clip


As many therapists tell you when you’re looking to change something, look at what you need to fix first, then start working on competing. If you read the linked document you’ll see how serious Microsoft is. Additionally there is now a lot of competitive positioning coming from VMware directly against Microsoft if for no other reason, than because Microsoft is taking itself seriously unlike it did in the past with regard to Hyper-V. Microsoft has vastly improved, simplified, and consolidated the plethora of old Hyper-V related documentation into a much simpler, approachable and digestible form that is actually more than useful and understandable. It’s meaningful. Microsoft has sent a warning shot across the bow of all competitor virtualization platforms (in the x86/commodity space anyway) and is sending a beacon to all those in the current Windows Server customer base that they really need to warrant this new effort with some alacrity for the future of Windows Server and built-in virtualization.

The jury is still out since there is a lot of testing in the enterprise space yet to do from an administrative and operational perspective, but if their follow through on product is anything like their preparation has led us to believe, then technologies like VMware, Citrix, Xen, RedHat and others will indeed have something to worry about.

The only gap left to jump will be the concept of putting all your eggs into the Microsoft basket, but Microsoft is working on that too.