Discover LUNs in Red Hat v5.5 without rebooting

[Marcus Schack]

Not sure if this is the correct place, but I am looking for a utility that I can use in Red Hat v5.5 that would "rescan" for newly presented LUNs from an EVA. Something similar to HP-UX "ioscan".

[Adam Garsha]

There is an hp_rescan tool in one of the kits that you should load install from hp. One kit for datamapper, one kit of utilities for your hba. One of kits includes fibreutils.

# rpm -qa --filesbypkg | egrep hp_rescan
fibreutils /opt/hp/hp_fibreutils/hp_rescan
fibreutils /usr/bin/hp_rescan

# sudo hp_rescan -h
NAME

hp_rescan

DESCRIPTION

Sends the rescan signal to selected or all fibre channel HBAs.

OPTIONS

-a, --all - Rescan all fibre channel HBAs
-h, --help - Prints this help message
-i, --instance - Rescan a particular instance where instance is a specific
SCSI host number
-l, --list - List all supported fibre channel HBAs

[Marcus Schack]

Quick question, we did this and it shows no HBAs, even though we already have 4 LUNs presented. Could it be that since booting from SAN,that this could be the issue?

[Adam Garsha]

To find the kits I am talking about. I think you can (assuming it is an hp server) search against the hba for driver/fw downloads perhaps, then choose your linux, and so forth. redhat after 5.3 has multipathing baked in, but there are still utility kits (like the hp_rescan) that prove useful also, installing the kits I think sets default recommended queue settings (from HP) for your HBA.

[Adam Garsha]

Oh, not sure on the issue you meantion. I haven't seen that. Look and see if the module is loaded for your hba's.

If they are emulex, you'd want to see I think "lpfc" listed in there somewhere with lsmod. It could be that the driver isn't getting loaded.

I don't boot from SAN so I am not sure of goings on here, but maybe you guys changed kernels and don't have the correct modprobe.conf or something. Again, I don't boot from SAN, but this is what my modprobe.conf looks like (excert):

options qla2xxx ql2xmaxqdepth=16 ql2xloginretrycount=30 qlport_down_retry=10
options lpfc lpfc_lun_queue_depth=16 lpfc_nodev_tmo=28 lpfc_discovery_threads=32

[Adam Garsha]

What I said makes little sense if you can see the disks. Please ignore my statements and I'll revert to "don't know".

[JKytsi]

echo 1 > /sys/class/fc_host/host/issue_lip

[JKytsi]

AND You do not have to install anything.

[Marcus Schack]

Ok... let me try this. Will get back to you on Tuesday to let you know how it worked.

[Rob Leadbeater]

Hi Marcus,

Alternatively you can use the rescan-scsi-bus.sh script provided by Red Hat in the sg3_utils package, as detailed here

https://access.redhat.com/kb/docs/DOC-39315

(copy attached if you can't get to Red Hat's KB)

Cheers,

Rob