Windows 2012 or Windows 2016 (including R2) hosts will by default issue SCSI "TRIM and Unmap" commands equivalent to the entire size of the Virtual Disk. This behavior is regardless if the 'Perform a quick format' option is checked. This results in significant amount of write I/O to the storage subsystem and significantly slows down the format process (can also cause heavy queuing on the FA)
On the windows host, disable the SCSI TRIM and Unmap feature for the duration of the format. Use fsutil command from the command line
- To verify the current setting, using a Windows CMD window on the Host, run:
fsutil behavior query DisableDeleteNotify
DisableDeleteNotify=0 -indicates the 'Trim and Unmap' feature is on (enabled)
DisableDeleteNotify=1 -indicates the 'Trim and Unmap' feature is off (disabled)
- To disable, issue the command:
fsutil behavior set DisableDeleteNotify 1
- Once formatting is complete, re-enable the feature using command:
fsutil behavior set DisableDeleteNotify 0