In regard to: Re: [Networker] Red Hat kernel version , Dag Nygren said (at...:

- more importantly (for us), the Red Hat 2.4.9.e-* kernels are NOT built
   with CONFIG_SCSI_MULTI_LUN=y, so having multiple devices on
   one target id (but different LUNs) was a problem.  There's probably a
   way around that issue (other than forcefully probing a particular LUN
   manually), but we found it easiest to just build our own kernel with
   multi-lun support enabled.

You can add the following line in /etc/modules.conf:
options scsi_mod max_scsi_luns=256 scsi_allow_ghost_devices=1

That's very good to know -- thanks for sharing!

I'm not sure I understand what enabling the scsi_allow_ghost_devices is
supposed to do, though.  Looking at the comments in scsi_scan.c, it looks
like this is only needed if you want to be able to access a device
that says it's offline.  Googling it has turned up hints that it's useful
for multipathing, but not much else.  Even Doug Gilbert's Linux SCSI
site doesn't provide much info on it.

Can you provide a link to some more thorough documentation on when this
option is needed?

Based on my reading of the two options, it seems like just the
"max_scsi_luns=256" might be enough to get non-0 lun probing working even
when CONFIG_SCSI_MULTI_LUN is not set in the kernel, but you obviously
know more about this than I do, so I'm guessing there's something I'm
missing.

Thanks again for sending this, it's been very useful.

Tim
--
Tim Mooney                              mooney AT dogbert.cc.ndsu.NoDak DOT edu
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