In a recent thread on the VMTN PowerCLI Community someone asked if it is possible to get historical hard disk statistics. I referred the user to my Datastore usage statistics post, where I showed how to use the “disk” metrics to get that information.
But getting the individual vDisk statistics is a bit more tricky compared to getting the datastore statistics, as I showed in that post. The “disk” metrics hold the information, but the Instance that points to the MoRef value of a VM makes it a bit more tricky to retrieve.
Be forewarned, the “disk” metrics hold usage data for all the vDisks that a specific VM has on a specific datastore. You will not be able to get individual vDisk statistics, unless the vDisks are stored on different datastores !
On the positive side, the “disk” metrics will allow you to see how your vDisks increase in size over time. For your Thick vDisks that increase will be by expanding them, and for your Thin vDisks it will also show the natural growth.
Last Sunday there appeared an interesting thread in the VMTN PowerCLI Community where one the questions was how to find all ‘Thin‘ virtual disks without passing via a virtual machine. The reason for this question was that most of the user’s virtual machines in Lab Manager are not registered on the vCenter Server.
My first idea was to use ‘Get-Datastore | Get-Harddisk‘ and then use the Extensiondata property to query the thinProvisioned property. Something like Arne did in his PowerCLI: Virtual Machine Disk (VMDK) info post. But that, unfortunately, doesn’t work since the Extensiondata property is $null in this case.
I know there are already numerous scripts to report on virtual hard disks and most of them without a doubt much better then what I came up with for this post.
The reason I started with this script was a question in the PowerCLI Community from Alan in his Thin Provisioned Disks post. He wanted to know if you could get the provisioned and the allocated disk size for a thin provisioned virtual disk.
On the Yellow Bricks blog there was today a very interesting entry called Performance : Thin Provisioning. Besides the link to the excellent VMware document called Performance Study of VMware vStorage Thin Provisioning, Duncan also included some tips and tricks.
Since I’m in favour of automating as much as possible in my vSphere environment, I decided to have a look how all this could be scripted.
One of the interesting new features in vSPhere is vStorage Thin Provisioning. I’m not going to explain what Thin Provisioning is all about. For that you can consult several knowledgeable blogs (for example this entry on Virtual Geek) and/or books (for example Scott Lowe’s excellent Mastering VMware vSphere 4.0).
The problem I have with Thin Provisioning, is that there are a lot of existing guests and templates out there that were created with Thick VMDKs in the past. The only documented way I could find to convert these Thick VMDKs to Thin VMDKs was to use svMotion from the vSphere client.
Now that is not a solution I want to (or can) use in an automated environment. Continue reading