>----- Original Message ----
>From: Dan Nelson <[email protected]>
>In the last episode (Mar 11), Leslie Jensen said:
>> The solution for me was to create a raidz which gave me the same amount of
>> space. Now I wonder, should I enable compression? Will it affect
>> performance?
>
>The default lzjb compression is very fast and won't consume much CPU. If
>you have lots of easily-compressabe data it should improve performance.
In informal testing I have found it depends on a lot of factors but is often a
net gain.
For instance, writes during testing
in a VM running FBSD8 w/ ZFS
writing to an attached single test "drive"
on my not-terribly-fast XP laptop
showed a significant improvement when I enabled compression on an FS, jumping
from about 5 MB/s to easily 8+ MB/s.
In testing at work on a FBSD8 guest on an ESX3.5 host running on a blade backed
by a lightly loaded set of 24 15krpm drives, I found enabling compression
didn't change much unless I tossed more than a single processor at it, at which
point the gains were more tangible though not spectacular.
I would suspect that it depends on the ratio of the speed of your CPU to the
speed of your hard disk subsystem. Faster CPUs with slower disks will benefit
more, slow CPUs with fast disks may even slow down. Obviously, what
constitutes "Fast" and "Slow" is the big sticking point. :)
_______________________________________________
[email protected] mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-questions
To unsubscribe, send any mail to "[email protected]"
