Hi Guys,
Sage has been furiously working away at fixing bugs in newstore and
improving performance. Specifically we've been focused on write
performance as newstore was lagging filestore but quite a bit
previously. A lot of work has gone into implementing libaio behind the
scenes and as a result performance on spinning disks with SSD WAL (and
SSD backed rocksdb) has improved pretty dramatically. It's now often
beating filestore:
http://nhm.ceph.com/newstore/newstore-5d96fe6-no_overlay.pdf
On the other hand, sequential writes are slower than random writes when
the OSD, DB, and WAL are all on the same device be it a spinning disk or
SSD. In this situation newstore does better with random writes and
sometimes beats filestore (such as in the everything-on-spinning disk
tests, and when IO sizes are small in the everything-on-ssd tests).
Newstore is changing daily so keep in mind that these results are almost
assuredly going to change. An interesting area of investigation will be
why sequential writes are slower than random writes, and whether or not
we are being limited by rocksdb ingest speed and how.
I've also uploaded a quick perf call-graph I grabbed during the
"all-SSD" 32KB sequential write test to see if rocksdb was starving one
of the cores, but found something that looks quite a bit different:
http://nhm.ceph.com/newstore/newstore-5d96fe6-no_overlay.pdf
Mark
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