From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ric Wheeler Subject: Re: [PATCHES] new barriers - 2 Date: Fri, 17 Apr 2009 10:26:56 -0400 Message-ID: <49E891B0.4080103@redhat.com> References: <4982D33E.60000@wpkg.org> <170fa0d20901300904l31d0c143ya02d6fb4de28c281@mail.gmail.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <170fa0d20901300904l31d0c143ya02d6fb4de28c281@mail.gmail.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Mike Snitzer Cc: linux-raid@vger.kernel.org, device-mapper development , Jens Axboe List-Id: dm-devel.ids Mike Snitzer wrote: > On Fri, Jan 30, 2009 at 5:15 AM, Tomasz Chmielewski wrote: > >>> Here I announce 2nd version my new barrier support patches: >>> http://people.redhat.com/mpatocka/patches/kernel/barriers/ >>> >>> They are against 2.6.29-rc3. >>> >>> The most important enhancement is that with these patches, device mapper >>> is able to send barrier requests to lower devices. >>> >> I guess it still won't work for those using LVM on md (Linux software RAID) >> because md lacks barrier support? Do you know if someone is working on it? >> > > md raid1 has supported barriers since 2.6.17 > > But I'm not aware of any md work being done to support barriers in > other raid levels. Judging by Neil Brown's thoughts on the matter > (from 2006) it would seem unlikely he is putting effort to it, please > see the following thread: > http://marc.info/?l=linux-raid&m=115321319003578&w=2 > http://marc.info/?l=linux-raid&m=115335249503450&w=2 > > cc'ing linux-raid to see if others have more insight > Neil, Hannes, Is Mike's assumption above still true - no plans/thoughts about doing barrier support for RAID5/6 and so on? At least some things (the null barrier op) are in place now since your summary of a couple years back, does this make it easier? Thanks! Ric