Am 13.04.2017 um 11:58 schrieb d tbsky:
2017-04-13 17:47 GMT+08:00 Reindl Harald <h.reindl@xxxxxxxxxxxxx>:
Am 13.04.2017 um 11:44 schrieb d tbsky:
2017-04-13 17:09 GMT+08:00 Reindl Harald <h.reindl@xxxxxxxxxxxxx>:
Am 13.04.2017 um 10:13 schrieb d tbsky:
Hi:
I just tried to install rhel 7.3 on a 4 disk raid6. it's a
minimal install but took 3 hours to finish. I found the disk
initialize speed is around 150MB/sec. in past the disk initialize
speed will down to slow speed when there are other disk IO, but it
seems not the case in rhel 7.3.
I have check the below parameter:
cat /proc/sys/dev/raid/speed_limit_min -> 1000
cat /proc/sys/dev/raid/speed_limit_max -> 200000
when the system is idle, the init speed is also about 150M/sec, so
the system is use all the power to init when there are other disk IO.
is it normal? where should I check?
sysctl.conf:
dev.raid.speed_limit_min = 10000
dev.raid.speed_limit_max = 50000
sysctl -p
and it will adjust itself within seconds - the same works if that values
are
too low and raid-check would take forever
hi: my problem is the speed is too high, not too low...
and?
you said it is at 200000
i showed you how to reduce it to 50000 or whatever you want
hi:
sorry I didn't understand you correctly. thanks for the hint. I
will try to resolve the root cause of the problem
the root cause is a default which is too large for your disks wqhile on
the other hand if someone has a RAID10 with SSD disks it's even too low
and you should just configure that for your needs and workload
it's not only about how fast are your disks, it's also about your
workload, there are times where i set it to 500000 to get the weekly
raid-scrub as fast as possible when i don't heavily use the machine and
on other days i slow it down dramatically because i need performance and
don't care when the background task is finished
it's also a difference between RAID1 or RAID10 when concurrency reads
can be served by the other disk and the impact is not so big than on a RAID1
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