vn(4) performance on 4.11 versus md(4) on 5.4
glenn at antimatter.net
Sun Jun 5 21:25:55 GMT 2005
(I sent this to freebsd-performance yesterday, but that list seems kind of
dead, so I'm trying this one. If there's a better place for me to send
this, let me know.)
I have a number of systems running 4.11 that have file backed virtual
disks, each of which contains a jail. I need to start using 5.4 for new
servers. The catch is, file backed virtual disks using md(4) seem to be
much slower than similar virtual disks on 4.11 using vn(4). vn(4) on 4.11
is about 2.24 times faster than the equivalent setup using md(4) on 5.4.
I've posted the results of some tests that I ran at
Is this decrease in performance known? Is there something I can do in
order to come close to the performance that 4.11 has? I've tried changing
some of the parameters of the filesystem on the virtual disk, but the
performance didn't change.
I can supply more info than what the link above has, if needed.
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