From mboxrd@z Thu Jan 1 00:00:00 1970 From: Milan Broz Subject: Re: trim support (discard) Date: Sun, 09 Jan 2011 14:28:16 +0100 Message-ID: <4D29B7F0.4050001@redhat.com> References: <1294515916.5136.6.camel@jaschtschik-pc> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1294515916.5136.6.camel@jaschtschik-pc> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development Cc: Jens Kasten List-Id: dm-devel.ids On 01/08/2011 08:45 PM, Jens Kasten wrote: > > I use the kernel 2.6.37 with cryptsetup and lvm on a intel ssd. Device-mapper targets supports discards in 2.6.37 with exception of dm-crypt target (that's why you see that message). Supporting discards in dm-crypt means that information about unused blocks is leaked (SSD ususally returns zeroes instead of expected random data for discarded blocks) and it it can be security problem in some situations. We will probably add discard support in dm-crypt later but as optional parameter (admin must decide that leaking allocated block info is not problem and must explicitly enable it). Probably 2.6.39 material. > Then i try the wiper.sh script and i get: > wiper.sh: Linux SATA SSD TRIM utility, version 3.1, by Mark Lord. > /dev/dm-1: unable to reliably determine the underlying physical device > name, aborting That seems like bug in that script btw, it should understand DM devices. > Its there in near future the discard support on the LVM? LVM/DM itself should fully support discards now. Exception is stacking with dm-crypt devices. Milan