Strange slowdown when cache devices enabled in ZFS

[Freddie Cash]

I do have the following set in /boot/loader.conf:
vfs.zfs.l2arc_write_boost="160000000"           # Set the L2ARC warmup
writes to 160 MBps
vfs.zfs.l2arc_write_max="320000000"             # Set the L2ARC writes to
320 MBps

Haven't tried setting them any higher than that, though.

During the "0 I/O periods", there's no I/O going to the cache devices
either, and they're anywhere from 50% full to almost 100% full (as shown in
"zpool list -v" and "zpool iostat" output).  ARC use is close to max,
though.



On Thu, Mar 14, 2013 at 11:41 AM, Daniel Kalchev <daniel at digsys.bg> wrote:

> Just an idea - have you tried to increase the L2ARC fill rate? That might
> move data faster from RAM to L2ARC.. Don't remember the says to offhand.
>
> Might be dedup kicking in and not able to get "swapped out" fast enough.
>
> Daniel




-- 
Freddie Cash
fjwcash at gmail.com