On Sun, Oct 28, 2007 at 11:43:16PM +0100, Michael van Elst wrote:
> RAID5 can be slow when you don't write full stripes, but even then
> it is usually not much slower than a single drive.

It might be some interaction of the RAID5 controller, FFS, and softdep.
It would be interesting to get some data points from other RAID5 users
out there.

> Some RAID controllers are also very slow when you disable the
> write cache. Can you verify your setup?

Unit  UnitType  Status         %Cmpl  Stripe  Size(GB)  Cache  AVerify  IgnECC
------------------------------------------------------------------------------
u0    SINGLE    OK             -      -       465.651   ON     OFF      -  
u1    RAID-5    OK             -      64K     4656.56   ON     OFF      OFF 

So, cache should be anabled.

  -jm