From mboxrd@z Thu Jan 1 00:00:00 1970 From: MRK Subject: Re: stuck tasks Date: Mon, 12 Apr 2010 14:49:48 +0200 Message-ID: <4BC316EC.9040808@shiftmail.org> References: <4BC2FE9E.9040802@shiftmail.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-reply-to: Sender: linux-raid-owner@vger.kernel.org To: Jeremy Sanders Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 04/12/2010 01:14 PM, Jeremy Sanders wrote: > MRK wrote: > > >> You need to lower the sync speed by catting a value into >> /sys/block/md{n}/md/sync_speed_max >> the value should be about 1/3 lower than the max speed you see (cat >> /proc/mdstat) now that it's not yet limited. >> Set up a script to set it at boot. >> > Thanks - I'll try it. It didn't happen in a raid sync, just during an rsync > run. Would this have any effect on normal operation? > !?!! Mistake of mine, but I might have gotten the right answer by chance I had read resyncing but you wrote rsyncing. But you were in fact also resyncing from what you write below: >> If it was not happening for you on older kernels might be a good sign: >> it might mean that the resync is faster now... >> >> What is the sync speed you see (cat /proc/mdstat)? How many drives do >> you have and what type of raid is that? >> > We're only getting 30MB/s. I thought it used to be quite a lot faster. It > seems to slow down as the sync progresses: > > [root@xback2 ~]# cat /proc/mdstat > Personalities : [raid6] [raid5] [raid4] > md0 : active raid5 sdb1[0] sdj1[10](S) sdk1[9] sdl1[8] sdi1[7] sdh1[6] > sdg1[5] sdf1[4] sde1[3] sdd1[2] sdc1[1] > 8788959360 blocks level 5, 32k chunk, algorithm 2 [10/10] [UUUUUUUUUU] > [>....................] resync = 1.4% (14078544/976551040) > finish=501.4min speed=31990K/sec > Resync speed is indeed quite low if you confirm there is no other disk activity. Instead if rsync is also running, you need to stop that one to have a proper resync speed measurement (to compute the value to be entered into sync_speed_max as per my previous email). Do you have disk write caches activated? See that with tw_cli (3ware's CLI) How much is /sys/block/md{n}/md/stripe_cache_size? Pump it up to 32768. > unused devices: > > The drives are connected to a single 3ware Inc 9650SE SATA-II RAID PCIe card > on this particular system. They're SATA 1GB drives. > > Jeremy >