Sysadmin

I've recently been experimenting with ZFS in a production environment, and have discovered some very interesting performance characteristics. I have seen many benchmarks indicating that for general usage, ZFS should be at least as fast if not faster than UFS (directio not withstanding - not that UFS directio itself is any faster, but anything that does it's own memory management such as InnoDB or Oracle will suffer from the double-buffering effect unless ZFS has been tuned appropriately), but nothing prepared me for what I discovered in my preliminary benchmarking.

To give a little background : I had been experiencing really bad throughput on our 3510-based SAN, which lead me to run some basic performance tests and tuning. During the course of this (and resolving some of the issues), I decided to throw ZFS into the mix. The hosts involved are X4100s, 12Gb RAM, 2x dual core 2.6Ghz opterons and Solaris 10 11/06. They are each connected to a 3510FC dual-controller array via a dual-port HBA and 2 Brocade SW200e switches, using MxPIO. All fabric is at 2Gb/s.

So far, pretty straightforward. I had been using iozone as my benchmarking tool (using a 512Mb file as that's the average table size for our databases), and compared a wide range of systems and configurations, from an Ultra 20 with 7200RPM SATA drives, to the X4100's internal 10K RPM SAS disks as well as LUNs made available from the SAN in a variety of RAID levels.

Some interesting results here, which I'll skip over for the moment (like the Ultra20 beating the X4100 and SAN in read performance!) - the kicker happens when I added ZFS into the mix as an experiment.

Continue reading "ZFS and caching for performance"