As documented on BoL, the recommended cluster size (Allocation Unit Size) for Sql Server files is 64K. For Windows drive, the recommended (or the default) is 4K. Let’s say you log into a new server and all of this is already configured, how do you query or figure out what was the allocated unit size (or Cluster size) of each drive?

There are two ways:

Method 1: Go to my computer >> right click on a drive letter >> Format >>

In the resulting window, you can see the allocation unit size already used for a given drive.

Allocation Unit Size From MyComputer

Method 2: Using command like commands.

This MSDN article has more details about this command, but the one I use is this:

[sourcecode language=”vb”]
fsutil fsinfo ntfsinfo t:
[/sourcecode]

This spits out a bunch of information about this drive and the one you are looking for is under the name ‘Bytes Per Cluster’.

Allocation Unit Size From Commands

Hope it helps,

_Sqltimes