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

Benjamin Kingston
Sat, 03 Sep 2016 03:46:59 -0000

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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