LUN Formatting is slow due to TRIM/SCRUB being enabled by default in Windows 2012R2

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Windows 2012 (including R2) Hosts will by default issue SCSI "TRIM and Unmap" commands equivalent to the entire size of the Virtual Disk. This behaviour is regardless if the 'Perform a quick format' option is checked. This will significantly slow down the format process.

There is an infinibox ticket to improve the handling of such cases - Improve response time of UNMAP when no mapped data

A ticket for HostPowerTools was also created to allow a workaround for this : Disable TRIM/UNMAP before formatting a volume, and re-enable it right after.

It is possible to disable the SCSI TRIM and Unmap feature on the Host for the duration of the format.

Using a Windows CMD window on the Host issue the command:

fsutil behavior set DisableDeleteNotify 1

To re-enable the feature use the following command:

fsutil behavior set DisableDeleteNotify 0

To verify the current setting use the following command:

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)

Information about this new feature can be found here.

 

 


 

 


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