FreeBSD & Software RAID

Matthew Seaman m.seaman at
Wed May 27 05:50:22 UTC 2009

Wojciech Puchar wrote:
>> You can make ZFS work on i386, but it requires very careful tuning and 
>> is not
>> going to work brilliantly well for particularly large or high-throughput
>> filesystems.
> you mean "high transfer" like reading/writing huge files. anyway not 
> faster than properly configured UFS+maybe gstripe/gmirror.

I mean high-throughput, as in bytes-per-second.  Whether that consists of a
very large number of small files or fewer larger ones is pretty much immaterial.
> for small files it's only fast when they will fit in cache, same with UFS

For any files, it's a lot faster when they can be served out of cache.  That's
true for any filesystem.  It's only when you get beyond the capacity of your
caches that things get interesting.

I really don't have any hard data on ZFS performance relative to UFS + geom.
However my feeling is that UFS will win at small scales, but that ZFS will
close the gap as the scale increases, and that ZFS is the clear winner when
you consider things other than direct performance -- manageability, resilience
to hardware failure or disk errors, etc.  Of course, "small scale" (ie. about
the same size as a single drive) is hundreds of GB nowadays, and growing.



Dr Matthew J Seaman MA, D.Phil.                   7 Priory Courtyard
                                                  Flat 3
PGP:     Ramsgate
                                                  Kent, CT11 9PW

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