I'm getting sub-optimal performance with an mmap based database
(mongodb) which is running on zfs of Solaris 10u9.
System is Sun-Fire X4270-M2 with 2xX5680 and 72GB (6 * 8GB + 6 * 4GB)
ram (installed so it runs at 1333MHz) and 2 * 300GB 15K RPM disks
- a few mongodb instances are running with with moderate IO and total
rss of 50 GB
- a service which logs quite excessively (5GB every 20 mins) is also
running (max 2GB ram use) - log files are compressed after some time to
bzip2.
Database performance is quite horrid though - it seems that zfs does not
know how to manage allocation between page cache and arc cache - and it
seems arc cache wins most of the time.
I'm thinking of doing the following:
- relocating mmaped (mongo) data to a zfs filesystem with only
metadata cache
- reducing zfs arc cache to 16 GB
Is there any other recommendations - and is above likely to improve
performance.
--
Iwan Aucamp
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