Re: Benchmark with FreeBSD 8.0 and pgbench

Joao,

Wow, thanks for doing this!

In general, your tests seem to show that there isn't a substantial
penalty for using ZFS as of version 8.0.

If you have time for more tests, I'd like to ask you for a few more tweaks:

(1) change the following settings according to conventional wisdom:
    wal_buffers = 8MB
    effective_cache_size = 9GB
    checkpoint_segments = 32
    on ZFS only: full_page_writes=off

(2) What scale were you using for the pgbench database?  I didn't see it
in the e-mail.  It would be worth testing:
    s = 10 (small database, in memory)
    s = 500 (7GB, ram mostly full)
    s = 1000 (14GB, slightly larger than ram)
    s = 3000 (43GB, much larger than ram)

If you were only testing a small size in your runs, then the only
Filesystem behavoir you were testing was the transaction log.

(3) Try a ZFS 128K record size

(4) Centos/Ext3 appears to have had better staying power with high
numbers of clients.  Can you continue testing with 50, 100 and 200
clients on that combination?  And with data=writeback,noatime on Ext3?

--
                                   -- Josh Berkus
                                      PostgreSQL Experts Inc.
                                      http://www.pgexperts.com