If you’re a SQL Server Pro you will know that the volumes the SQL log and datafiles are stored on should be formatted with a 64K cluster size. This is a SQL Server Best practice as stated in this link.
To find out what the allocation unit size is for a drive you would run the command below:
fsutil fsinfo ntfsinfo [your drive]
Running the same command on a test system on the E:\ drive I get the following result:
C:\>fsutil fsinfo ntfsinfo E: NTFS Volume Serial Number : 0x0c76bbd176bbba32 NTFS Version : 3.1 LFS Version : 2.0 Number Sectors : 0x00000000013fe7ff Total Clusters : 0x0000000000027fcf Free Clusters : 0x0000000000027d5b Total Reserved : 0x0000000000000000 Bytes Per Sector : 512 Bytes Per Physical Sector : 512 Bytes Per Cluster : 65536 Bytes Per FileRecord Segment : 1024 Clusters Per FileRecord Segment : 0 Mft Valid Data Length : 0x0000000000010000 Mft Start Lcn : 0x000000000000c000 Mft2 Start Lcn : 0x0000000000000001 Mft Zone Start : 0x000000000000c000 Mft Zone End : 0x000000000000cca0 Resource Manager Identifier : 28DB2529-6D43-11E6-80C7-00505693BAC6
As you can see from the above, the Bytes Per Cluster is equal to 65,536 bytes or 64K.
You would have to run this command for every drive that you want to check. I found this handy piece of PowerShell code that gets just the allocation unit size for all disks in the system:
$wql = "SELECT Label, Blocksize, Name FROM Win32_Volume WHERE FileSystem='NTFS'" Get-WmiObject -Query $wql -ComputerName '.' | Select-Object Label, Blocksize, Name
The result of which would look similar to this on a system running SQL Server:
The results above show which disks are configured with the default 4K allocation unit size and those configured with 64K which are the SQL disks.
How To Determine Your Hard Disks Cluster Size
SQL Server Best Practices Article
Disk Partition Alignment Best Practices for SQL Server
Get Cluster size for all disks and volumes on a Windows machine using powershell and wmi