Re: RAID10 performance with 20 drives

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Hello!
Roman, i've updated the kernel to 4.11 and started "check" action,
results are basically the same, output on github
https://gist.github.com/CoolCold/663de7c006490d7fd0ac7cc98b7a6844
1 cpu is overloaded, not more than 1.3 - 1.4GB/sec

On Wed, May 31, 2017 at 9:14 PM, Roman Mamedov <rm@xxxxxxxxxxx> wrote:
> On Wed, 31 May 2017 19:20:10 +0700
> CoolCold <coolthecold@xxxxxxxxx> wrote:
>
>> Creation (disable write intent bitmap, with bitmap all is much worse):
>> mdadm --create -c 64 -b none -n 20 -l 10 /dev/md1 /dev/sde /dev/sdf
>> /dev/sdg /dev/sdh /dev/sdi /dev/sdj /dev/sdk /dev/sdl /dev/sdm
>> /dev/sdn /dev/sdo /dev/sdp /dev/sdq /dev/sdr /dev/sds /dev/sdt
>> /dev/sdu /dev/sdv /dev/sdw /dev/sdx
>>
>> kernel:
>> [root@spare-a17484327407661 rovchinnikov]# cat /proc/version
>> Linux version 3.10.0-327.el7.x86_64 (builder@xxxxxxxxxxxxxxxxxxxxxxx)
>> (gcc version 4.8.3 20140911 (Red Hat 4.8.3-9) (GCC) ) #1 SMP Thu Nov
>> 19 22:10:57 UTC 2015
>>
>> So, the question is - why cpu usage is so high and I suppose is a limit here?
>
> Definitely try a newer kernel, 4.4 at the very least; if no changes then 4.11.
>
> Also I would suggest to try out larger chunk sizes, such as 512 and 1024 KB.
>
> If you plan to use this long-term in production, also read up on the various
> RAID10 data layouts and their benefits and downsides (man md, search for
> "layout"; and search the Internet for benchmarks of all three).
>
> --
> With respect,
> Roman



-- 
Best regards,
[COOLCOLD-RIPN]
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