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

[Benjamin Kingston]

Thanks for the help, see below:

On Sat, Sep 3, 2016 at 11:41 AM, Mohammed Rafi K C <rkavunga at redhat.com>
wrote:

> Files created before attaching hot tier will be present on hot brick until
> it gets heated and migrated completely. During this time interval we won't
> get the benefit of hot storage since the files are served from cold brick.
>
The issue I'm having is that when the hot tier is added read from the
volume drops from 150MB/s (no tier) to 2-10MB/s (tier added). I experienced
this issue for a while even after the hot brick reached 90% capacity, so
many files were promoted.
I detached the hotbrick and verified there weren't any files left over, and
the performance was still effected.
It was only until I committed the detach that throughput returned to
150MB/s.

Reattaching the hot tier immediately caused the issue to return until the
tier was again detach-committed

>
>
> For smallfiles (order of kbs), We are experiencing some performance issue
> mostly with  EC (disperse ) volume.
>
> Follow up questions,
> What is the volume type ? and version of glusterfs ?
>
The volume is a 2x replica on btrfs bricks that are luks encrypted. 2048K
GPT offset for 1st partition . Gluster 3.8.3, built aug 22 running on
Centos.

>
> Does reread gives an equal performance when it hits the server ?
> reading any files with hot tier results in 2-10MB/s (node mounted volume
> via localhost6:/volume), reading them again any number of times does not
> improve performance
>


> Have you done any rename for those files ?
>
Some files have been renamed, however the 10GB test file has not it is the
original name/copy
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