[linux-lvm] thin discards
shentino at gmail.com
Sun Jul 21 11:01:54 UTC 2013
Do snapshots behave the same way as thin volumes wrt discards?
On Sun, Jul 21, 2013 at 3:47 AM, Zdenek Kabelac <zkabelac at redhat.com> wrote:
> Dne 21.7.2013 09:10, Raymond Jennings napsal(a):
> So can thin volumes support discards independently of the device
>> underneath them?
>> I expected fstrim to free space in the thin pool.
> Yes - you are expecting it correctly.
> Ignore is mostly usable in case you do not want to free already
> provisioned space - which might be in certain cases better for performance.
> But you need to use recent enough kernels and lvm2 tools - since discards
> support required kernel updates.
Are these versions recent enough?
Upstream has this:
> passdown TRIM -> thin-vol -> thin-pool -> PV
> (if the PV doesn't support discard - you get kernel report error report
> and it fallbacks to nopassdown behaviour)
> nopassdown TRIM -> thin-vol -> thin-pool
> ignore TRIM -> thin-vol
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