Monday, January 25, 2010

[Setup] Making sure your disks are optimized

(update 2014: at this point, the newer OSs take care of this.  And you.... never.... get LUNs mapped over from old servers, right?  *grin*)

At this point, probably everyone knows that you need to make sure to format your drives properly to take full advantage of them. There's two different issues: the cluster size, and the offset.

Practically, you want the offset to be 1024kb (leaves room for SAN "headers"), and the block size to be 64k.

(Link to MS whitepaper, which includes pretty charts showing major improvement:

Here's how to make sure.

Block size.
c:\users\you> fsutil fsinfo ntfsinfo d:

That will give you a bunch of info. What you care about is the Bytes Per Cluster, which should be 65536 (aka 64k)

Cluster offset:

> diskpart
> list disk
> select disk 1 (or whichever disk you want to look at)
> list partition

Look for the "offset" column

Powershell: See!EA42395138308430!291.entry
for a powershell script.

To format a drive properly:
list disk
select disk 2
create partition primary align=1024
format fs=ntfs unit=64K label="yourdrivenamehere" nowait

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