Re: [dm-devel] info on enabling only one path with rdac and DS4700

[Gianluca Cecchi <gianluca cecchi gmail com>]

On Mon, Nov 28, 2011 at 9:13 PM, Gianluca Cecchi wrote:
> On Mon, Nov 28, 2011 at 7:05 PM, Moger, Babu wrote:
[snip]
>> RHEL 5.7 has the patch already as I know. You can check to be sure. Can you also add "scsi_mod.scsi_logging_level=5056" in kernel line to get more information on what else is going on.
>
> Ok, I have verified that the patch should be applied.
[snip]
> So I'm going to add the scsi logging parameter you suggested and see.
>

Unfortunately it seems that rh el 5.x kernel doesn't support that
scsi_mod kernel module option directly at kernel line
# cat /proc/cmdline
ro root=/dev/VolGroup00/LV_root rhgb quiet scsi_mod.scsi_logging_level=5056

In messages:
Nov 29 07:00:03 testserver kernel: Unknown boot option
`scsi_mod.scsi_logging_level=5056': ignoring

So I picked up the new initrd with the scsi_dh part and put directly
that option at insmod statement line for scsi_mod module in initrd
init file, creating another special grub.conf stanza for this initrd
See messages and output of dmesg with this parameter at the links below

https://docs.google.com/open?id=0BwoPbcrMv8mvNzU1ZTNlY2UtY2E5Ni00NDdlLWIyY2UtZmQ0Y2I4OTJmNTZi
and
https://docs.google.com/open?id=0BwoPbcrMv8mvZmUxNTNmNjgtOTZmMi00YTBiLTkyZTktZWU0NTdjZWI4OWZm

At the end of boot:
mpath1 (3600a0b80005012440000093e4a55cf33) dm-6 IBM,1814      FAStT
[size=3.4T][features=1 queue_if_no_path][hwhandler=1 rdac][rw]
\_ round-robin 0 [prio=0][active]
 \_ 3:0:1:1 sdc 8:32  [active][undef]
 \_ 4:0:1:1 sde 8:64  [active][undef]
\_ round-robin 0 [prio=0][enabled]
 \_ 3:0:0:1 sdb 8:16  [active][undef]
 \_ 4:0:0:1 sdd 8:48  [active][undef]

Hope it helps you understanding better what doesn't go as expected..
Thanks for your time

Gianluca