From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Cracauer Subject: Re: Giving top priority to a rebuild instead of serving userland? Date: Mon, 9 Jan 2012 16:57:59 -0500 Message-ID: <20120109215759.GA85361@cons.org> References: <20120109142116.GA34289@cons.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Alexander Lyakas Cc: Martin Cracauer , linux-raid@vger.kernel.org List-Id: linux-raid.ids Alexander Lyakas wrote on Mon, Jan 09, 2012 at 10:40:49PM +0200: > Hi, > > Have you tried to play with: > /proc/sys/dev/raid/speed_limit_max > /proc/sys/dev/raid/speed_limit_min > /sys/block/mdXXX/md/sync_speed_min > /sys/block/mdXXX/md/sync_speed_max > > For me these work very well. You can also set min > max, in which case > max is totally ignored. > According to the kernel code, md keeps submitting sync requests until > it reaches the minimum speed, and then it checks the "userland" IO and > the high speed limit. Looks like what I need. Thanks so much. These two sets are identical in functionality (other than one being per-set), right? Martin > Alex. > > > On Mon, Jan 9, 2012 at 4:21 PM, Martin Cracauer wrote: > > I am doing a resize on a 4 x 1 TB raid5 array (going to 5x 1 TB). > > > > When there is no userland I/O it reports about 1000 minutes to > > rebuild. ?However, minor amount of userland demand makes it shoot up > > to 3500-4000 as the rebuild puts it's own interests behind. > > > > However, the I/O there is garbage, in this case a disk-noisy web > > browser. ?Can I tell md to give priority to it's rebuild and serve > > userland as it pleases with -say- a maximum of 10% rebuild time > > increase? Yes I know that'll make the system very sluggy. > > > > I would be finished already but overnight I left a browser tab open > > that caused according to iostat 400-500 Blk_wrtn contiguously. ?That > > is when *not* actually using the browser (I'll report that as a bug). > > Now I am still at 38% rebuild. ?Didn't seem worth the price I payed :-) > > > > Martin > > -- > > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > > Martin Cracauer ? http://www.cons.org/cracauer/ > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at ?http://vger.kernel.org/majordomo-info.html -- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Martin Cracauer http://www.cons.org/cracauer/