mpt(4) enabling write cache on raw disk

[Darren Baginski]

29.07.2012, 17:00, "Stefan Johansson" <steve.johansson at telia.com>:
> Hello!
>
> I have a HP 3080X SAS/SATA 8 port mpt(4) controller card that I want to use in
> a ZFS setup.
> My problem is that the write cache is not enabled on disks that are not a part of a RAID volume (RAID0 or RAID1).
> The write speed is limited to about 20MB/s with both UFS and ZFS.
> If I create a RAID0 volume with mptutil(8) and then destroy it, write cache gets enabled and the write speed reaches about 60MB/s with UFS and ZFS.
> Unfortunately it won't survive a reboot.
>
> Has anyone else seen this problem with mpt(4) controllers and/or knows how to fix it?

I have to create 8 raid0 volumes consisting of one drive, and then enable 
#/usr/sbin/mptutil volume  cache  0 enable
#/usr/sbin/mptutil volume  cache  1 enable