Disk defrag on active snapshots?

[ranjitcool]

Hey Guys,

While going through some docs I read this - "Never do a disk defrag in a vm that has active snapshots" - Now why is that - because it will simply defrag the disk but write that data in the snapshot file rather than actually doing it at the block level on the vmdk file?

Please comment

R

[Dave_Mishchenko · Accepted solution]

Essentially the concern is that the snapshot files could inflate very quickly and consume a lot of space.  If the partition is significantly fragmented, then all those changes are written the the snapshot file.  So you could end up with large snapshots files as well as a period of heavy IO.  You'll also have an I/O impact when you consolidate the changes in the snapshot back to the main virtual disk file.

[ranjitcool]

Cool thanks, thought the same

R