read/write benchmarking: UFS2 vs ZFS vs EXT3 vs ZFS RAIDZ vs Linux MDRAID

[Dan Naumov]

> What confuses me about these results is that the '5 disk' performance was
> barely higher than the 'single disk' performance.  All figures are also
> lower than I get from a single modern SATA disk.
>
> My own testing with dd from /dev/zero with FreeBSD ZFS an Intel ICH10
> chipset motherboard with Core2duo 2.66ghz showed RAIDZ performance scaling
> linearly with number of disks:
>
>
> What               Write   Read
> --------------------------------
> 7 disk RAIDZ2      220     305
> 6 disk RAIDZ2      173     260
> 5 disk RAIDZ2      120     213

What's confusing is that your results are actually out of place with
how ZFS numbers are supposed to look, not mine :) When using ZFS
RAIDZ, due to the way parity checking works in ZFS, your pool is
SUPPOSED to have throughput of the average single disk from that pool
and not some numbers growing skyhigh in a linear fashion.

The numbers that did surprise me the most were actually gmirror reads
(results posted earlier to this list): a geom gmirror is consistently
SLOWER for reading that a single disk (and it only gets progressively
worse the more disks you have in your gmirror). Read performance of
all other mirroring implementations pretty much scale up linearly with
the amount of disks present in the mirror.


- Sincerely,
Dan Naumov