Do snapshots behave the same way as thin volumes wrt discards?
On Sun, Jul 21, 2013 at 3:47 AM, Zdenek Kabelac <zkabelac@redhat.com> wrote:
Dne 21.7.2013 09:10, Raymond Jennings napsal(a):Yes - you are expecting it correctly.
So can thin volumes support discards independently of the device underneath them?
I expected fstrim to free space in the thin pool.
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.
Kernel: 3.10.1-gento
LVM2: 2.02.97
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
Zdenek
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