[Gluster-users] Fwd: Very slow performance when enabling tierd storage with SSD

Mohammed Rafi K C rkavunga at redhat.com
Sat Sep 3 07:07:03 UTC 2016


Hi Benjamin,


Can you tell us more about your work-load like the file size, size of
both hot and cold storage, how the files are created (after attaching
the tier or before attaching the tier) , how long have you been using
the tier volume, etc.


Regards

Rafi KC




On 09/03/2016 09:16 AM, Benjamin Kingston wrote:
> Hello all,
>
> I've discovered an issue in my lab that went unnoticed until recently,
> or just came about with the latest Centos release.
>
> When the SSD hot tier is enabled read from the volume is 2MB/s, after
> detaching AND committing, read of the same file is at 150MB/s to /dev/null
>
> If I copy the file to the hot bricks directly the write is 150MB/s and
> read is 500MB/s on the first read, and then 4GB/s on the subsequent
> reads (filesystem RAM caching) to /dev/null
>
> Just enabling tier storage takes the performance to ~10-20IOPS and
> 2-10MB/s even for local node mounted volume.
>
> I don't see any major log issues and I detached and did a fix-layout,
> but it persists when re-enabling the tier.
>
>
>
>
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