immense delayed write to file system (ZFS and UFS2), performance issues

[Dimitry Andric]

On 2010-01-27 00:15, Dan Naumov wrote:
> Can anyone confirm that using the WDIDLE3 utility on the 2TB WD20EADS
> discs will not cause any issues if these disks are part of a ZFS
> mirror pool? I do have backups of data, but I would rather not spend
> the time rebuilding the entire system and restoring enormous amounts
> of data over a 100mbit network unless I absolutely have to :)

Sorry to bump into this thread so late, but for some of my servers I
have been using a patch for atacontrol, to turn the APM features of the
disk(s) off, for a long time.  This is mostly noticable with 2.5"
notebook disks, which "click" like crazy all the time. :)

E.g. if you run "atacontrol cap $device", and you see in the output that
"advanced power management" is supported, you might be able to stop the
disk from spinning down by turning the APM feature off.

Patch is at <http://www.andric.com/freebsd/atacontrol-apm.diff>.  This
should apply to 8-STABLE, no idea about older branches.