zfs discuss - Oct 2009 - MPT questions

In an attempt to recycle some old PATA disks, we bought some
really cheap PATA/SATA adapters, some of which actually work
to the point where it is possible to boot from a ZFS installation
(e.g., c1t2d0s0). Not all PATA disks work, just Seagates, it would
seem, but not Maxstors. I wonder why? probe-scsi-all sees
Seagate but not Maxstor disks plugged into the same adapter.

Such disks have proven invaluable as a substitute for rescue
CDs until such CDs become possible.

The odd thing is that booting from another disk, ZFS can''t see
the adapted disk even though it is bootable. Could the reason
be that there''s no /dev/rdsk/c1t2d0, but there are c1t0d0, etc.?
Format sees the disk but zpool import doesn''t (this is on SPARC
sun4u). This isn''t at all important, just curious as to why this
might be and why zpool import can''t see it at all, but zpool
create can.

Gotta say how happy we are with the MPT driver and the LSI
SAS controller - fast and reliable - petabytes of i/o and not a
single zfs checksum error!

This has little to do with ZFS, but should it be possible to
see a PATA CD or DVD connected to an MPT (LSI) SAS controller
via one of these adapters? Though I''d ask before forking out
for a SATA DVD drive - just hate to put perfectly good drives
out for recycling. Maybe someone can recommend a writable
BlueRay SAS drive  that is known to work with the MPT driver
instead...

Thanks -- Frank

Frank Middleton wrote:
> In an attempt to recycle some old PATA disks, we bought some
> really cheap PATA/SATA adapters, some of which actually work
> to the point where it is possible to boot from a ZFS installation
> (e.g., c1t2d0s0). Not all PATA disks work, just Seagates, it would
> seem, but not Maxstors. I wonder why? probe-scsi-all sees
> Seagate but not Maxstor disks plugged into the same adapter.
> 
> Such disks have proven invaluable as a substitute for rescue
> CDs until such CDs become possible.
> 
> The odd thing is that booting from another disk, ZFS can''t see
> the adapted disk even though it is bootable. Could the reason
> be that there''s no /dev/rdsk/c1t2d0, but there are c1t0d0, etc.?
> Format sees the disk but zpool import doesn''t (this is on SPARC
> sun4u). This isn''t at all important, just curious as to why this
> might be and why zpool import can''t see it at all, but zpool
> create can.
> 
> Gotta say how happy we are with the MPT driver and the LSI
> SAS controller - fast and reliable - petabytes of i/o and not a
> single zfs checksum error!
> 
> This has little to do with ZFS, but should it be possible to
> see a PATA CD or DVD connected to an MPT (LSI) SAS controller
> via one of these adapters? Though I''d ask before forking out
> for a SATA DVD drive - just hate to put perfectly good drives
> out for recycling.
It might work. It certainly wouldn''t hurt to try.


James C. McPherson
--
Senior Kernel Software Engineer, Solaris
Sun Microsystems
http://blogs.sun.com/jmcp	http://www.jmcp.homeunix.com/blog