From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: bad performance on RAID 5 Date: Thu, 18 Jan 2007 18:01:03 -0500 Message-ID: <45AFFC2F.4070000@tmr.com> References: <45AE9640.1040500@start.no> <45AEA550.5070005@lucidpixels.com> <5d96567b0701180106x5441f24dp117ffebdf560a23f@mail.gmail.com> <45AFBA62.1060206@start.no> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <45AFBA62.1060206@start.no> Sender: linux-raid-owner@vger.kernel.org To: Sevrin Robstad Cc: "Raz Ben-Jehuda(caro)" , linux-raid@vger.kernel.org List-Id: linux-raid.ids Sevrin Robstad wrote: > I've tried to increase the cache size - I can't measure any > difference..... You probably won't help small writes, but large writes will go faster with a stripe cache of size num_disks*chunk_size*2 or larger. > > Raz Ben-Jehuda(caro) wrote: >> did u increase the stripe cache size ? >> >> >> On 1/18/07, Justin Piszcz wrote: >>> Sevrin Robstad wrote: >>> > I'm suffering from bad performance on my RAID5. >>> > >>> > a "echo check >/sys/block/md0/md/sync_action" >>> > >>> > gives a speed at only about 5000K/sec , and HIGH load average : >>> > >>> > # uptime >>> > 20:03:55 up 8 days, 19:55, 1 user, load average: 11.70, 4.04, 1.52 >>> > >>> > kernel is 2.6.18.1.2257.fc5 >>> > mdadm is v2.5.5 >>> > >>> > the system consist of an athlon XP1,2GHz and two Sil3114 4port S-ATA >>> > PCI cards with a total of 6 250gb S-ATA drives connected. >>> > >>> > [root@compaq ~]# mdadm --detail /dev/md0 >>> > /dev/md0: >>> > Version : 00.90.03 >>> > Creation Time : Tue Dec 5 00:33:01 2006 >>> > Raid Level : raid5 >>> > Array Size : 1218931200 (1162.46 GiB 1248.19 GB) >>> > Device Size : 243786240 (232.49 GiB 249.64 GB) >>> > Raid Devices : 6 >>> > Total Devices : 6 >>> > Preferred Minor : 0 >>> > Persistence : Superblock is persistent >>> > >>> > Update Time : Wed Jan 17 23:14:39 2007 >>> > State : clean >>> > Active Devices : 6 >>> > Working Devices : 6 >>> > Failed Devices : 0 >>> > Spare Devices : 0 >>> > >>> > Layout : left-symmetric >>> > Chunk Size : 256K >>> > >>> > UUID : 27dce477:6f45d11b:77377d08:732fa0e6 >>> > Events : 0.58 >>> > >>> > Number Major Minor RaidDevice State >>> > 0 8 1 0 active sync /dev/sda1 >>> > 1 8 17 1 active sync /dev/sdb1 >>> > 2 8 33 2 active sync /dev/sdc1 >>> > 3 8 49 3 active sync /dev/sdd1 >>> > 4 8 65 4 active sync /dev/sde1 >>> > 5 8 81 5 active sync /dev/sdf1 >>> > [root@compaq ~]# >>> > >>> > >>> > Sevrin >>> > - >>> > 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 >>> >>> If they are on the PCI bus, that is about right, you probably should be >>> getting 10-15MB/s, but it is about right. If you had each drive on its >>> own PCI-e controller, then you would get much faster speeds. -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979