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
zfs-discuss mailing list

Reply via email to