> > On Mon, Jun 24, 2013 at 07:37:56PM +1000, Russell Coker wrote: > > On Mon, 24 Jun 2013, Craig Sanders <[email protected]> wrote: > > > if you can, use the third SATA port for the RAID-Z array as well - > > > RAID-Z gets better performance when the number of data disks in an > > > array is a power of 2 (e.g. 4 data disks + 1 parity for RAID-Z1, or > > > 4 data disks + 2 parity for RAID-Z2). > > > > The SATA disks will just be for booting. They won't have ZFS because > > root on ZFS was way too much pain to even consider last time I looked > > into it. Also I think we are a long way from having ZFS root be > > reliable enough that I would even consider using it on a remote system > > with no other forms of boot available. > > i made no mention of having root on ZFS. that's a completely unrelated > topic. > > I was pointing out that there is a small but noticable performance > benefit with ZFS RAID-Z arrays if you have a power-of-two number of > *data* disks - e.g. 2, 4, or 8 data disks. > > with 5 SAS ports, you can have 4 data disk (yes, a power of 2) and 1 > parity for RAID-Z1. Or you can have three data disks (NOT a power of 2) > and 2 parity disks for RAID-Z3.
With old hardware like that I would nominate the 5th disk as a hot spare so on failure you have minimum "degraded" time. This assumes that ZFS can handle a hot spare drive. James _______________________________________________ luv-main mailing list [email protected] http://lists.luv.asn.au/listinfo/luv-main
