From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <51EBBC47.4040508@redhat.com> Date: Sun, 21 Jul 2013 12:47:35 +0200 From: Zdenek Kabelac MIME-Version: 1.0 References: <51E51D8E.2000801@redhat.com> In-Reply-To: Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] thin discards Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Raymond Jennings Cc: LVM general discussion and development 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