Re: Number of devices that SCSI can support

[Andrew Vasquez <andrew.vasquez@qlogic.com>]

On Wed, 09 Jan 2008, Matthew Wilcox wrote:

> On Wed, Jan 09, 2008 at 09:05:52AM -0600, James Bottomley wrote:
> > On Tue, 2008-01-08 at 19:22 -0700, Matthew Wilcox wrote:
> > > On Tue, Jan 08, 2008 at 04:55:46PM -0800, Vinay Venkataraghavan wrote:
> > > > Is there a limit on the number of devices that SCSI supports. In other words, I have a QLogic HBA card, and I am connecting to a SAN which has 64 targets. 
> > > 
> > > I've personally had over five hundred LUNs.  You shouldn't be hitting a
> > > limit here.
> > 
> > I believe the largest test that's been run was the old OSDL CGL
> > workgroup ... they went up to 4096.
> > 
> > However, LUN support depends on the driver and HBA parameters as well
> > (some choose to have arbitrary limits).
> 
> I was using a qlogic HBA for my tests, so I don't think this is the
> problem -- although the original poster claims to have 64 targets, and I
> had only one target with 128 luns (attached 4 times).
> 
> -- 
> Intel are signing my paycheques ... these opinions are still mine
> "Bill, look, we understand that you're interested in selling us this
> operating system, but compare it to ours.  We can't possibly take such
> a retrograde step."

Not sure what's going on as well, perhaps some logs could help... But
the inbox qla2xxx driver in RHEL4 set's an HBA's scsi_host->max_id
count to 512 (also verified with several test rings), so there
shouldn't be a problem handling 64 distinct targets (FC ports).