I have read several threads about reshaping being very slow. I am seeing
it myself when I converted 3-disk (2TB each) raid5 to 4-disk (again, 2TB
each) raid6. I am only getting about 8M rate. I tried all sorts of
things with /proc and /sys variables. Nothing helped. Each time I set
something, I get a temporary boost to 10M/s, and after a little while,
it settles down back to 8M/s rate.
I have currently very little in terms of useful files in the raid
(about 100G). I also took a fresh backup before the reshape and
unmounted md0. Would it be faster if I trash the raid5 and create raid6
from scratch instead of reshape? Any guess on how much faster? I
typically got 100+M on checkarray cron jobs. It would fire around 1-2AM
and finish by 6-7AM on first Sun. Reshape has been running more than a
day and has only about 45% done.
BTW, this is really old machine with SATA 3.0G and Athlon 64 X2 (max
freq 2Ghz). I also checked that my cpu is not running out of gas. In
fact on-demand governet has reduced the freq to 1Ghz with about 50% cpu
load. However uptime shows 2.7 jobs in the ready queue. Here are the
actual outputs. Please let me know if I missed any optimization.
lata:/home/rramesh# blockdev --getra /dev/sdb (all other sdx's also
havethe same value)
131072
lata:/home/rramesh# cat /proc/sys/dev/raid/speed_limit_max
200000
lata:/home/rramesh# cat /proc/sys/dev/raid/speed_limit_min
100000
lata:/home/rramesh# cat /sys/block/md0/md/stripe_cache_active
0
lata:/home/rramesh# cat /sys/block/md0/md/stripe_cache_size
16384
lata:/home/rramesh# cat /sys/block/md0/md/sync_speed
9265
lata:/home/rramesh# cat /sys/block/md0/md/sync_speed_max
200000 (system)
lata:/home/rramesh# cat /sys/block/md0/md/sync_speed_min
200000 (local)
lata:/home/rramesh# cat /sys/block/md0/md/chunk_size
524288
lata:/home/rramesh# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid6 sde1[4] sdb1[0] sdd1[3] sdc1[1]
3906763776 blocks super 1.2 level 6, 512k chunk, algorithm 18
[4/3] [UUU_]
[=========>...........] reshape = 46.1%
(902017024/1953381888) finish=1907.6min speed=9184K/sec
unused devices: <none>
lata:/home/rramesh# iostat -xd 10 3
Linux 3.2.0-4-amd64 (lata) 08/12/2014 _x86_64_ (2 CPU)
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s
avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.01 0.07 0.09 0.10 2.63 4.15
70.84 0.00 8.34 1.67 14.77 0.54 0.01
sdb 2240.97 2241.60 39.15 23.44 18327.30 9040.86
874.57 1.38 22.11 18.74 27.74 10.41 65.16
sdc 2240.41 2241.53 39.70 23.50 18327.36 9040.80
866.07 1.10 17.49 12.23 26.38 9.23 58.36
sdd 2240.28 2241.47 39.84 23.56 18327.44 9040.83
863.38 1.03 16.21 10.96 25.09 8.68 55.03
sde 0.02 2240.73 0.01 24.08 0.03 9039.95
750.62 0.37 15.49 0.91 15.49 10.18 24.53
sdf 0.00 3.82 0.10 43.64 0.40 18869.21
862.92 2.29 52.34 1.37 52.45 5.01 21.93
md0 0.00 0.00 9.32 0.35 758.03 1.39
157.08 0.00 0.00 0.00 0.00 0.00 0.00
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s
avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdb 2155.90 2158.60 37.30 23.10 17561.60 8809.15
873.20 1.51 25.11 22.94 28.62 11.33 68.44
sdc 2155.90 2158.60 37.40 23.00 17579.20 8757.95
872.09 1.13 18.74 11.99 29.70 10.11 61.04
sdd 2155.90 2158.50 37.50 23.10 17630.40 8757.95
870.90 0.97 16.09 10.65 24.94 9.27 56.16
sde 0.00 2158.10 0.00 23.50 0.00 8757.95
745.36 0.40 16.95 0.00 16.95 11.78 27.68
sdf 0.00 2.20 0.00 41.70 0.00 18057.20
866.05 1.59 38.25 0.00 38.25 4.78 19.92
md0 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00 0.00 0.00
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s
avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdb 1980.20 1980.80 31.80 20.70 15718.40 7989.55
903.16 1.52 28.92 24.42 35.85 13.78 72.36
sdc 1980.20 1980.70 31.70 20.80 15700.80 7989.55
902.49 0.99 18.92 14.35 25.88 10.30 54.08
sdd 1980.00 1980.90 31.70 20.60 15598.40 7989.55
902.02 0.89 16.99 11.81 24.95 9.23 48.28
sde 0.00 1980.10 0.00 21.40 0.00 7989.55
746.69 0.35 16.13 0.00 16.13 11.07 23.68
sdf 0.00 1.80 0.00 34.30 0.00 14774.80
861.50 1.53 44.79 0.00 44.79 5.36 18.40
md0 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00 0.00 0.00
Thanks in advance for your help. Even the assurance that I have done
everything except waiting for a finish will make me feel better :-)
I wonder if my reshape is so slow because of constant seeks rather than
read. All my disks are 5400 rpm (two WD green and two Samsung Ecogreen 5400)
I forgot, I did check SMART data, and did not find anything bad.
Regards
Ramesh
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
