MPS driver: force bus rescan after remove SAS cable

[Jeremy Chadwick]

On Wed, Apr 27, 2011 at 08:07:34PM -0700, Rumen Telbizov wrote:
> I confirm I experience the same behavior with just a SAS expander not
> via SAS switch.  I've got no way to get my block device back but
> reboot.

I don't mean to sound critical, but why do you guys do this?  The reason
I ask: on actual production filers (read: NetApps), you don't go yanking
out the FC cable between the HBA and the NA and expect everything to "be
happy" afterwards.  Most SAN administrators tend to reboot an appliance
when doing this kind of work -- because this kind of work is considered
maintenance.

I understand what you folks are reporting is a problem.  I'm just
wondering why you're complaining about having to reboot a machine with
an HBA in it after doing this kind of *physical* cabling work.  My
immediate thought is "I'm really not surprised".  I guess some other
people *are* surprised.  :-)

> Also identify function doesn't work from the OS (no problem
> via the card BIOS). Don't remember having any luck with sg3_util
> package either but worth trying again.

I don't use SAS myself, but wouldn't the command be "inquiry" and not
"identify"?  "identify" is for ATA (specifically SATA via CAM), while
"inquiry" is for SCSI.  Where SAS fits into this is unknown to me.

> On a related note: recently LSI released version 9.0 of their firmware
> for SAS2008 and I found it fixes certain performance problems with
> SuperMicro backplanes!

In another thread, or a PR, if you could provide those technical details
that would be beneficial.  There are a very large number of FreeBSD
users who use Supermicro server-class hardware, and I'm certain they
would be interested in a full disclosure.

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.               PGP 4BD6C0CB |