While waiting for a rather large RAID5 array to build, I noticed the
following output from iostat -k 1:
Linux 2.6.11-1.1369_FC4smp (justinstalled.syd.nighthawkrad.net)
04/07/05
avg-cpu: %user %nice %sys %iowait %idle
1.10 0.00 5.24 2.45 91.21
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
hda 7.79 58.17 46.26 82741 65802
sda 86.70 8221.20 391.64 11693016 557032
sdb 81.11 8221.16 15.06 11692952 21416
sdc 80.85 8221.18 14.16 11692980 20136
sdd 80.93 8221.20 15.06 11693016 21416
sde 81.01 8221.20 15.37 11693016 21864
sdf 80.79 8221.20 14.16 11693016 20136
sdg 80.91 8221.20 14.52 11693016 20648
sdh 79.67 8221.16 6.91 11692952 9832
sdi 78.95 8221.20 0.03 11693016 40
sdj 79.04 8221.20 0.03 11693016 40
sdk 79.48 8221.20 0.03 11693016 40
sdl 93.28 0.33 8269.91 472 11762288
md0 1.60 0.00 102.28 0 145472
avg-cpu: %user %nice %sys %iowait %idle
0.49 0.00 7.35 0.00 92.16
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
hda 0.00 0.00 0.00 0 0
sda 100.99 9417.82 0.00 9512 0
sdb 101.98 9417.82 0.00 9512 0
sdc 100.00 9417.82 0.00 9512 0
sdd 98.02 9417.82 0.00 9512 0
sde 96.04 9417.82 0.00 9512 0
sdf 96.04 9417.82 0.00 9512 0
sdg 96.04 9417.82 0.00 9512 0
sdh 96.04 9417.82 0.00 9512 0
sdi 99.01 9417.82 0.00 9512 0
sdj 100.00 9417.82 0.00 9512 0
sdk 99.01 9417.82 0.00 9512 0
sdl 109.90 0.00 9504.95 0 9600
md0 0.00 0.00 0.00 0 0
avg-cpu: %user %nice %sys %iowait %idle
0.00 0.00 5.53 0.00 94.47
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
hda 0.00 0.00 0.00 0 0
sda 102.02 9765.66 0.00 9668 0
sdb 108.08 9765.66 0.00 9668 0
sdc 108.08 9765.66 0.00 9668 0
sdd 108.08 9765.66 0.00 9668 0
sde 103.03 9765.66 0.00 9668 0
sdf 103.03 9765.66 0.00 9668 0
sdg 103.03 9765.66 0.00 9668 0
sdh 102.02 9765.66 0.00 9668 0
sdi 105.05 9765.66 0.00 9668 0
sdj 105.05 9765.66 0.00 9668 0
sdk 103.03 9765.66 0.00 9668 0
sdl 120.20 0.00 9696.97 0 9600
md0 0.00 0.00 0.00 0 0
avg-cpu: %user %nice %sys %iowait %idle
0.00 0.00 6.00 0.00 94.00
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
hda 0.00 0.00 0.00 0 0
sda 109.90 9500.99 0.00 9596 0
sdb 103.96 9500.99 0.00 9596 0
sdc 107.92 9500.99 0.00 9596 0
sdd 106.93 9500.99 0.00 9596 0
sde 104.95 9500.99 0.00 9596 0
sdf 102.97 9500.99 0.00 9596 0
sdg 104.95 9500.99 0.00 9596 0
sdh 102.97 9500.99 0.00 9596 0
sdi 101.98 9500.99 0.00 9596 0
sdj 101.98 9500.99 0.00 9596 0
sdk 101.98 9500.99 0.00 9596 0
sdl 154.46 0.00 9536.63 0 9632
md0 0.00 0.00 0.00 0 0
avg-cpu: %user %nice %sys %iowait %idle
0.00 0.00 5.50 0.00 94.50
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
hda 0.00 0.00 0.00 0 0
sda 100.99 9401.98 0.00 9496 0
sdb 100.00 9401.98 0.00 9496 0
sdc 98.02 9401.98 0.00 9496 0
sdd 100.00 9401.98 0.00 9496 0
sde 97.03 9401.98 0.00 9496 0
sdf 94.06 9401.98 0.00 9496 0
sdg 95.05 9401.98 0.00 9496 0
sdh 96.04 9401.98 0.00 9496 0
sdi 96.04 9401.98 0.00 9496 0
sdj 95.05 9401.98 0.00 9496 0
sdk 97.03 9401.98 0.00 9496 0
sdl 127.72 0.00 9600.00 0 9696
md0 0.00 0.00 0.00 0 0
avg-cpu: %user %nice %sys %iowait %idle
0.00 0.00 5.97 0.00 94.03
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
hda 2.00 0.00 32.00 0 32
sda 90.00 9676.00 0.00 9676 0
sdb 91.00 9676.00 0.00 9676 0
sdc 90.00 9676.00 0.00 9676 0
sdd 90.00 9676.00 0.00 9676 0
sde 90.00 9676.00 0.00 9676 0
sdf 89.00 9676.00 0.00 9676 0
sdg 89.00 9676.00 0.00 9676 0
sdh 89.00 9676.00 0.00 9676 0
sdi 89.00 9676.00 0.00 9676 0
sdj 89.00 9676.00 0.00 9676 0
sdk 89.00 9676.00 0.00 9676 0
sdl 124.00 0.00 9600.00 0 9600
md0 0.00 0.00 0.00 0 0
Devices sd[a-l] make up /dev/md0:
[root@justinstalled ~]# cat /proc/mdstat
Personalities : [raid5]
md0 : active raid5 sdl[12] sdk[10] sdj[9] sdi[8] sdh[7] sdg[6] sdf[5]
sde[4] sdd[3] sdc[2] sdb[1] sda[0]
1719198976 blocks level 5, 128k chunk, algorithm 2 [12/11]
[UUUUUUUUUUU_]
[>....................] recovery = 2.4% (3837952/156290816)
finish=256.7min speed=9895K/sec
unused devices: <none>
[root@justinstalled ~]#
Why are all the writes concentrated on a single drive ? Shouldn't the
reads and writes be being distributed evenly amongst all the drives ?
Or is this just something unique to the rebuild phase ?
CS
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