[Users] Performance degradation on 042stab113.X

[Karl Johnson]

Disks are fine and RAID is optimal. It doesn't happen only when backups run
but it's easier to see during this time. What's strange is that there were
no issue on <108 kernels.

It could have been this following patch from RedHat but 113 isn't based on
2.6.32-573.22.1, 114 will be I think.


** Due to prematurely decremented calc_load_task, the calculated
loadaverage was off by up to the number of CPUs in the machine.
(BZ#1300349)*

Karl

On Tue, Mar 29, 2016 at 3:35 PM, Gena Makhomed <gmm at csdoc.com> wrote:

> On 29.03.2016 21:03, Karl Johnson wrote:
>
> Every weekend I do backups of all CT which take a lot of IO. It didn't
>> affect much load average before 108 but as soon as I upgraded to 113, load
>> got very high and nodes became sluggish during backups. It might be
>> something else but I was looking for feedback if someone else had the same
>> issue. I will continue to troubleshoot this issue. Meanwhile, I will
>> upgrade them from 113.12 to 113.21 and see how it goes even if there's
>> nothing related to this in the changelog.
>>
>
> See smartctl - temperature of HDDs and seek/read errors.
>
> Reason of "nodes became sluggish during backups"
> can be high HDD temp and high seek/read errors rate.
>
> Also see free space on backup partition - if free space
> low it will be very fragmented and write will be slow
> - need many IOPS for write many small file chunks.
>
> --
> Best regards,
>  Gena
>
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