mfi - setting up disks

[Scott Long]

On Sep 24, 2010, at 4:45 PM, Dag-Erling Smørgrav wrote:
> Niklas Saers <niklas at saers.com> writes:
>> In the SuperMicro system where I had problems with the mpt controller,
>> I switched it for a mfi-based controller. I had it set up with 36x
>> RAID0 volumes with each their own disk (no way to access the disk
>> otherwise I found), and added them to a ZFS system. The numbering
>> became a bit weird, so I pulled the disks out one by one and put them
>> back to figure out and note down what disk number was in what
>> slot. Only test data on my ZFS volume, so I didn't mind that crashing.
> 
> You can wire down SCSI buses and disks in /boot/device.hints so each
> disk always gets the same device number regardless of the order in which
> the disks spin up.  The syntax is documented in /sys/conf/NOTES (search
> for "SCSI DEVICE CONFIGURATION").  It's a CAM feature, and mfi uses CAM,

MFI only uses CAM for passthrough access to component drives, not for normal I/O.  Setting CAM wiring hints will not solve the problem at hand.  And the problem at hand isn't really even numbering, it's that the MFI firmware freaked out and marked the disks inaccessible.  I think that this happened to us at Yahoo once, and we eventually gave up and replaced the disks.  Putting the disks on a non-LSI, non-RAID controller and writing 0's to the last 10MB worth of sectors (or just writing 0's to the entire drive) will likely solve the problem, but YMMV.

Scott