VCritical » CSV

Live Migration “significantly more complicated”

Eric Gray — Fri, 23 Oct 2009 12:40:08 +0000

It can be difficult to set up a complete Hyper-V environment. There are a lot of user interfaces needed to perform the various configuration tasks — especially during initial deployment. It’s great to see that the mainstream technology media has arrived at the same conclusion.

Jason Brooks, Executive Editor at eWeek, recently reviewed Windows Server 2008 R2 and had the following to say about Live Migration and Cluster Shared Volumes (CSV):

Live Migration was very easy to use, but I found the process of configuring and using Live Migration in Windows Server 2008 R2 significantly more complicated than with VMware ESX server and VirtualCenter. In contrast to VMware’s product, where all tasks are gathered together in a purpose-built interface, the tasks required to configure Cluster Shared Volumes in Windows Server involve visits to various existing and new Windows utilities.

It’s true. The Microsoft virtualization solution is a conglomeration, and configuring all of the various layers, roles, and features on top of the general-purpose Windows OS is complicated.

You may need Windows to run parts of your business, but that doesn’t mean you need Hyper-V. Take control of Windows — by running it on rock-solid, purpose-built, enterprise-class VMware vSphere — before it takes control of you.

Simplify, don’t complexify.

Hyper-V Administrators Exhibit Advanced Memory Skills

Eric Gray — Mon, 12 Oct 2009 22:06:28 +0000

The Windows You Know™ formerly assigned letters of the alphabet to storage volumes. With the introduction of Cluster Shared Volumes (CSV), drive letters are no longer used — relying instead on a 128-bit globally unique identifier (GUID). In other words, what used to be called the “F drive” is now known as \\?\Volume{d5ad02f4-4e30-11ed-b1db-ca8c6df4064b}\.

While in some contexts the difference is minimal, one obviously affected area is monitoring with System Center Operations Manager 2007 (SCOM), which exposes volume GUIDs in various user interfaces:

In related news, an interesting report recently published by a top medical journal found that those in a relatively new information technology position known as “Hyper-V Administrator” exhibited strongly enhanced memory recall capabilities. This correlation is thought to be a result of the rigorous, albeit unintentional, mental training these personnel undergo in the course of their daily responsibilities.

“It appears to be a classic case of the Von Restorff effect,” said Dr. Sedgwick McCaskey, primary contributor to the research and author of the best-seller Don’t Forget IT.

The report also went on to explain that some “Hyper-V Administrators” have found mnemonic devices to be a great help in their jobs. “Instead of trying to remember all of those random letters and numbers, I sometimes make up songs or rhymes,” said one anonymous participant in the study.

It’s great to see nimble professionals that are able to quickly adapt in the face of change. Especially considering the fact that every new Windows Server 2008 R2 system has a hidden 100 MB partition created automatically during installation by default. And since that volume has no drive letter, it shows up in SCOM with – you guessed it – the volume GUID:

Ouch. Pass the Ginkgo.

Just to be clear: three paragraphs of this article are satire; the rest is factual. If you can’t figure out which is which, feel free to ask.

Hands off that CSV!

Eric Gray — Fri, 18 Sep 2009 16:39:11 +0000

Cluster Shared Volumes (CSV) is the new Microsoft Hyper-V R2 feature that allows virtual machines to be saved as plain text files and then imported into a spreadsheet or database for editing. Wait… that’s a different kind of CSV.

Actually, CSV is a layer on top of NTFS shared storage that provides some of the functionality of a cluster filesystem — multiple hosts can access a single LUN simultaneously. No more one VM per LUN jokes, please.

Unlike VMware VMFS, CSV relies on a single coordinator node for all metadata updates to the LUN — interesting.

The Secret Sauce

It turns out that CSV is a delicate feature and files on such a volume should never be managed directly. In an effort to protect Hyper-V administrators from themselves, Microsoft has taken an interesting non-technical approach to preventing CSV misuse.

After installing Windows Server 2008 R2, configuring storage LUNs, enabling Failover Clustering, and adding cluster nodes, CSV must be enabled on the cluster. In the process of doing so, a dialog box is presented that looks much like an end-user license agreement:

The text inside the box states the following:

The Cluster Shared Volumes feature is only supported for use with Windows Server 2008 R2 Hyper-V role. Creation, reproduction and storage of files on Cluster Shared Volumes that were not created by the Hyper-V role, including any user or application data stored under the ClusterStorage directory of the system drive on every node, are not supported and may result in unpredictable behavior, including data corruption or data loss on these shared volumes.

In order to proceed, administrators much check a box indicating that they have read the notice. Note: If you are the one that checked the box in your organization, please be sure to pass the warning on to your coworkers.

Backups? Someday.

What about backup (“reproduction”) of virtual machines stored on the CSV LUNs? You cannot simply take backups of VM files like you would on a normal volume. In fact, if you attempt to back up any files on a Cluster Shared Volume by using the native Windows Server Backup tool, the following error is thrown:

Which leaves the Hyper-V administrator with just one option at this point: in-guest backups only. Eventually, System Center Data Protection Manager will support backing up Hyper-V VMs, but not right now.

Check out this hilarious ZDNet article bashing VMFS — they didn’t happen to mention any of these CSV advantages.

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