mfi - setting up disks

[Niklas Saers]

Hi Scott & Dag-Erling,

On Sep 26, 2010, at 1:25 AM, Scott Long wrote:
> 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.

Indeed, "mfiutil locate" gave us all we needed for identifying the disk, so numbering is no longer an issue. Thanks for the tip on how to get the disk back up, I'll make sure we try that this week.

I tried the let-the-RAID-controller-make-RAIDs-and-join-them-via-ZFS model on the mpt-based controller, and that made performance drop from ~250 mb/sec to ~4 mb/sec. With mfi (the system is otherwise unchanged), the average speed is ~200 mb/sec, down ~50 mb/sec.

Cheers

	Nik