Options for zfs inside a VM backed by zfs on the host
Quartz
quartz at sneakertech.com
Fri Aug 28 00:12:56 UTC 2015
> I am right now exploring the question: are SSD ZILs necessary in an all SSD
> pool?
Something mentioned in another recent thread on this list (or maybe it
was -questions?) was that yes, you really should consider a separate ZIL
if you're using primarily SSDs. Without a separate disk, log writes have
to steal blocks from the pool itself which then have to be deleted
afterwards to let go of the space. Besides causing excess file
fragmentation, the write-delete cycle doesn't play well with SSDs and
trim and can seriously hamper performance. With a dedicated disk, it
writes and then just leaves it there, only overwriting later if necessary.
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