added note about tempdb allocation unit size (Issue 48343)

Author: MashaMSFT

articles/virtual-machines/windows/sql/virtual-machines-windows-sql-performance.md

@@ -130,7 +130,7 @@ For VMs that support premium SSDs, you can also store TempDB on a disk that supp
      > [!WARNING]
      > Stop the SQL Server service when changing the cache setting of Azure VM disks to avoid the possibility of any database corruption.
 
-* **NTFS allocation unit size**: When formatting the data disk, it is recommended that you use a 64-KB allocation unit size for data and log files as well as TempDB.
+* **NTFS allocation unit size**: When formatting the data disk, it is recommended that you use a 64-KB allocation unit size for data and log files as well as TempDB. If TempDB is placed on the temporary disk (D:\ drive) the performance gained by leveraging this drive outweighs the need for a 64K allocation unit size. 
 
 * **Disk management best practices**: When removing a data disk or changing its cache type, stop the SQL Server service during the change. When the caching settings are changed on the OS disk, Azure stops the VM, changes the cache type, and restarts the VM. When the cache settings of a data disk are changed, the VM is not stopped, but the data disk is detached from the VM during the change and then reattached.