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Re: [Linux-cluster] fcntl locking lockup (dlm 1.07, GFS 6.1.5, kernel 2.6.9-67.EL)

On Wed, 2008-01-09 at 15:47 -0600, Kevin Anderson wrote:
> Sorry, Lon gave me updated info about the MSA500.  It isn't a parallel
> shared scsi bus configuration, so might work with gfs.  However, we
> have never run with it before and not sure about the performance
> characteristics.

It's a multi-port SCSI RAID array, but it's not a multi-initiator
parallel SCSI bus (which absolutely does not work with GFS: ex: Dell
PowerVault 220S).

The MSA500 has an on-box RAID controller with multiple SCSI ports, which
are attached using SCSI cables to CCISS controllers in the host
machines.  While CCISS are host-RAID controllers, as I understand it,
when talking to MSA500 arrays, they act just like dumb SCSI controllers
(that are 10x the cost of regular dumb SCSI controllers, of course!) -
and do nothing "intelligent" at all - leaving it up to the MSA
controller to handle all the RAID operations.

Also, if I'm not mistaken, each port on the MSA RAID controller is
actually its own SCSI (well, cciss) bus, so you shouldn't hit typical
SCSI bus problems.  For example, you should not see bus resets for
example during reboot of one of the nodes.

-- Lon

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