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Date: Sun, 21 Jul 2013 21:40:38 +0200
From: Zdenek Kabelac <zkabelac@redhat.com>
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Subject: Re: [linux-lvm] thin discards
Reply-To: LVM general discussion and development <linux-lvm@redhat.com>
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To: Raymond Jennings <shentino@gmail.com>
Cc: LVM general discussion and development <linux-lvm@redhat.com>

Dne 21.7.2013 13:01, Raymond Jennings napsal(a):
> 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
> <mailto: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?

Nope - 2.02.98 has fixes for discards - it's been just introduced in 2.02.97 
and had some problems - possible those you can observe.

Zdenek