lkml.org 
[lkml]   [2013]   [Sep]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectAnomaly with 2 x 840Pro SSDs in software raid 1
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!


\
 
 \ /
  Last update: 2013-09-20 15:41    [W:0.023 / U:9.604 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site