[linux-lvm] thin discards

[Zdenek Kabelac]

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.

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