From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754831Ab3ITNdq (ORCPT ); Fri, 20 Sep 2013 09:33:46 -0400 Received: from gts6.roserve.net ([128.140.230.209]:42519 "EHLO gts6.roserve.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754668Ab3ITNdp (ORCPT ); Fri, 20 Sep 2013 09:33:45 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 20 Sep 2013 15:22:04 +0300 From: Andrei Banu To: linux-kernel@vger.kernel.org Subject: Anomaly with 2 x 840Pro SSDs in software raid 1 Message-ID: User-Agent: Roundcube Webmail/0.9.3 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gts6.roserve.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - redhost.ro X-Get-Message-Sender-Via: gts6.roserve.net: authenticated_id: andrei.banu@redhost.ro Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, We have a troubling server fitted with 2 840Pro Samsung SSDs. Besides other problems addressed also here a while ago (to which I have still found no solution) we have one more anomaly (or so I believe). Although both SSDs worked 100% of the time their wear is very different. /dev/sda has a wear of 95% while /dev/sdb has a wear of 77%. The total number of LBAs is different only by 9.76%. But the wear level is with 463.75% higher for sdb. Shouldn't these be proportional? root [~]# smartctl --attributes /dev/sda smartctl 5.43 2012-06-30 r3573 [x86_64-linux-2.6.32-358.11.1.el6.x86_64] (local build) ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 9 Power_On_Hours 0x0032 099 099 000 Old_age Always - 4014 12 Power_Cycle_Count 0x0032 099 099 000 Old_age Always - 5 177 Wear_Leveling_Count 0x0013 095 095 000 Pre-fail Always - 149 241 Total_LBAs_Written 0x0032 099 099 000 Old_age Always - 18515581190 root [~]# smartctl --attributes /dev/sdb smartctl 5.43 2012-06-30 r3573 [x86_64-linux-2.6.32-358.11.1.el6.x86_64] (local build) ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 9 Power_On_Hours 0x0032 099 099 000 Old_age Always - 4014 12 Power_Cycle_Count 0x0032 099 099 000 Old_age Always - 5 177 Wear_Leveling_Count 0x0013 077 077 000 Pre-fail Always - 840 241 Total_LBAs_Written 0x0032 099 099 000 Old_age Always - 20324371103 A 'iostat -x' returns this: Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 10.10 46.15 803.26 121.32 8672.87 1543.00 11.05 0.33 0.36 0.06 5.47 sdb 9.15 52.77 318.00 114.68 4577.24 1543.00 14.14 0.20 0.47 0.30 13.16 md1 0.00 0.00 1.41 1.29 11.27 10.36 8.00 0.00 0.00 0.00 0.00 md2 0.00 0.00 1119.61 164.21 10796.10 1530.64 9.60 0.00 0.00 0.00 0.00 md0 0.00 0.00 0.42 0.01 3.20 0.01 7.46 0.00 0.00 0.00 0.00 Shouldn't also the %util of 2 members of the same raid-1 array be the same? Also svctm seems very different by a similar factor of x5. A little background info about the system: - CentOS 6.4 - Linux 2.6.32-358.11.1.el6.x86_64 #1 SMP Wed Jun 12 03:34:52 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux - E3-1270v2, 16GB RAM, SuperMicro SYS-5017C-MTRF, 2 x Samsung 840 Pro 512GB in mdraid-1 - cat /proc/mdstat md0 : active raid1 sdb2[1] sda2[0] 204736 blocks super 1.0 [2/2] [UU] md2 : active raid1 sdb3[1] sda3[0] 404750144 blocks super 1.0 [2/2] [UU] md1 : active raid1 sdb1[1] sda1[0] 2096064 blocks super 1.1 [2/2] [UU] Kind regards!