From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Friesen Subject: Re: RFC: use TRIM data from filesystems to speed up array rebuild? Date: Tue, 04 Sep 2012 14:28:59 -0600 Message-ID: <5046648B.8010905@genband.com> References: <50464322.3010509@genband.com> <20120905062113.05e4f0f4@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120905062113.05e4f0f4@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 09/04/2012 02:21 PM, NeilBrown wrote: > On Tue, 04 Sep 2012 12:06:26 -0600 Chris Friesen > wrote: >> Hi, >> >> I'm not really a filesystem guy so this may be a really dumb question. >> >> We currently have an issue where we have a ~1TB RAID1 array that is >> mostly given over to LVM. If we swap one of the disks it will rebuild >> everything, even though we may only be using a small fraction of the space. >> >> This got me thinking. Has anyone given thought to using the TRIM >> information from filesystems to allow the RAID code to maintain a >> bitmask of used disk blocks and only sync the ones that are actually used? >> >> Presumably this bitmask would itself need to be stored on the disk. > Something like this? > http://neil.brown.name/blog/20110216044002#5 Something like that would indeed cover the use-case that triggered this. Chris