Red Hat Bugzilla – Bug 435974
[EMC/QLogic 5.2 bug] When using qla2462 only 512 LUNS discoverd.
Last modified: 2009-06-19 22:33:26 EDT
In RHEL 5.1 EMC is finding they are unable to discover more then 512 LUNS. The system is a Symm and it
is configured to provide LUNS 257-2048.
$ cat /proc/scsi/scsi |grep scsi8 | wc –l
Output of a driver with debugging attached.
It is not yet clear if this is a driver or system problem, but will ascertain and update...
It appears there are boot time parameters to the RHEL Linux scsi module that control this behaviour.
This may not have been discovered during testing because a single target was not used to provide all the
Haifeng, could you try modifying your boot command line in /boot/grub.conf to include something like:
Marcus, I'm assuming this isn't a regression from RHEL 5.0?
At the moment it just looks like we need a release note or documentation. It seems the kernel needs
a boot parameter to find more then 512 LUNS from a single target. It appears the testing for number of
LUNS was done with multiple targets contributing to the total.
So not a regression...
Either Haifeng will get back to us or I will be able to work with QA here to look at the problem soon...
We were able to set max_report_luns in /etc/modprobe.conf and scan 1000+
devices. We've tried passing scsi_mod.max_scsi_report_luns on the grub boot
line but it fails saying it's an unknown parameter.
(In reply to comment #4)
> We've tried passing scsi_mod.max_scsi_report_luns on the grub boot
> line but it fails saying it's an unknown parameter.
That was probably caused by my mistake in an mail on the subject. The parameter
name is max_report_luns. The value it is stored in in the code is
module_param_named(max_report_luns, max_scsi_report_luns, int, S_IRUGO|S_IWUSR);
"REPORT LUNS maximum number of LUNS received (should be"
" between 1 and 16384)");
So, scsi_mod.max_scsi_luns should work.
(In reply to comment #5)
> So, scsi_mod.max_scsi_luns should work.
That should be scsi_mod.max_report_luns. Brother.
I've prematurely closed this BZ. We were unable to get this to pass on the grub
boot command line, see comment 6. We did use scsi_mod.max_report_luns=4096 and
it returned the error. Please advise.
Module parameters for loadable modules are specified only as the
parameter name with optional '=' and value as appropriate, such as:
modprobe usbcore blinkenlights=1
Module parameters for modules that are built into the kernel image
are specified on the kernel command line with the module name plus
'.' plus parameter name, with '=' and value if appropriate, such as:
Our problem is that scsi_mod is not built in to the kernel. It is loaded after
the kernel, too late for the command-line options to be applied. Looks like
modprobe.conf is the way to go. Sorry about that.
By the way, you can have the user check to make sure the parameter took effect
by looking at
A user can also change it there
echo 4096 > /sys/module/scsi_mod/parameters/max_report_luns
after the module is loaded. But then they would have to use additional sysfs
writes to cause a rescan of the targets. Not very practical.