On 24/06/14 18:15, Robert van Leeuwen wrote:
All of which means that Mysql performance (looking at you binlog) may
still suffer due to lots of small block size sync writes.
Which begs the question:
Anyone running a reasonable busy Mysql server on Ceph backed storage?
We tried and it did not perform good enough.
We have a small ceph cluster: 3 machines with 2 SSD journals and 10 spinning
disks each.
Using ceph trough kvm rbd we were seeing performance equal to about 1-2
spinning disks.
Reading this thread it now looks a bit if there are inherent architecture +
latency issues that would prevent it from performing great as a Mysql database
store.
I'd be interested in example setups where people are running busy databases on
Ceph backed volumes.
Yes indeed,
We have looked extensively at Postgres performance on rbd - and while it
is not Mysql, the underlying mechanism for durable writes (i.e commit)
is essentially very similar (fsync, fdatasync and friends). We achieved
quite reasonable performance (by that I mean sufficiently encouraging to
be happy to host real datastores for our moderately busy systems - and
we are continuing to investigate using it for our really busy ones).
I have not experimented exptensively with the various choices of flush
method (called sync method in Postgres but the same idea), as we found
quite good performance with the default (fdatasync). However this is
clearly an area that is worth investigation.
Regards
Mark
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