Michael wrote:
Hello,
iam reshaping my 4-drive raid5 to a 5-drive raid6, but the speed is a
little slow.
md2 : active raid6 sdc3[0] sdg3[4] sdf3[3] sda3[2] sdd3[1]
2898182016 blocks super 0.91 level 6, 64k chunk, algorithm 18 [5/4]
[UUUU_]
[======>..............] reshape = 34.2% (330530816/966060672)
finish=2897.5min speed=3655K/sec
i know it is a expensive process, but my system near-to-idle, so there may
be something wrong.
with top, i can see there is no noticable cpu load caused by the md2_raid6
process or any other.
with iotop, i can see mdadm reading and writing a little data once a
secound, but not continuous.
i think the kernel's raid io is not visible at iotop or iam wrong?
i have moved the --backup-file from my usb drive to a internal ide hard
drive and gained 800k/sec more speed.
~3000-4000k/sec are not so bad that the reshaping takes forever, but could
be faster, right?
i have tried playing around with sync_speed_min and sync_speed_max without
any result.
setting the stripe_cache to 8192 or something did not show a real
performance gain.
You can go larger than that, double it or try 32k. I have heard reports
of evil at 64k, I wouldn't go there other than with test data.
is my speed bad, good, normal? any ideas how to "tune" it a bit?
--
Bill Davidsen <davidsen@xxxxxxx>
"We can't solve today's problems by using the same thinking we
used in creating them." - Einstein
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