Performance difference between UFS and ZFS with NFS
Daniel Kalchev
daniel at digsys.bg
Wed Nov 27 12:32:18 UTC 2013
On 25.11.13 21:24, Eric Browning wrote:
> Steven,
>
> I've tried to 4K align these SSDs with gnop but they are currently ashift
> 9. Pool layout is just 4 drives in a zfs stripe. I've also tried raidz1
> with no noticeable performance impacts other than a loss of space for
> parity.
>
ashift=9 with most (all?) SSDs is a big no-no! You really should make
that pool ashift=12 (at least) and have it 4k aligned (partition).
Especially for writes, an properly aligned 4 drive SSD stripe should be
way faster.
Here is what I get from ashift=12 raidz1 4 SSD drive pool
# dd if=/dev/zero of=zero bs=1m count=1k
1024+0 records in
1024+0 records out
1073741824 bytes transferred in 1.817027 secs (590933382 bytes/sec)
Unfortunately, your only option is dump / recreate pool / restore. (zfs
send/receive is an option too -- especially if you have another set of
drives)
Daniel
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