Monday, December 18, 2006

Netadmin: Using diskpart to extend a volume onto a new disk

To follow-up on a comment in a previous post, Teo Heras makes the point that you can use basic or dynamic disks to dynamically extend the file system of the of an existing volume onto a different disk. As he points out, Microsoft uses this in support of their "just-in-time" storage provisioning , which basically allows them to provision capacity on-demand and without downtime.

Which is a good point - just throw a few drives in, provision them in a supportable hardware RAID configuration (using your Dell, HP, etc. management tools), then you can use diskpart to extend the filesystem of one of your volumes onto the new capacity of the additional disk. And since the RAID configuration is invisible to the OS, drives can still be failed/replaced without the OS complaining, or your extended file system caring.

You can find a good KB article here if you're interested. Otherwise, the short of it is as follows...

1) Add drives to server.
2) Configure drives in a supportable hardware RAID configuration.
3) Open a command prompt, and launch "diskpart".
4) Type "list volume", and find the volume you want to extend.
5) Type "select volume 1" where 1=the volume you want to extend (let's call it "e").
6) Type "list disk" (let's assume disk 2 is the new disk that you just added).
7) Type "extend disk=2". This will extend the filesystem of volume 1 ("e") onto the additional capacity of the new drive.

That's all there is to it. You can extend the capacity of the drive the OS resides on as well if needed. Just keep in mind that if you're using a hardware RAID, you're not looking to use dynamic disks for the software RAID functionality, rather you're using diskpart to extend the filesystem and provision storage.

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