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Re: [linux-lvm] thin discards

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):

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.

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


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