Rescanning LUN's after adding/removing storage

[Tom Callahan_1]

We are currently using HP FCA2214 FC HBA's to connect to an EVA 5000 for SAN based storage. The systems are running RHEL ES 4, and using the qlogic drivers with failover support.

Our problem lies in the removal of presentation and addition of presentation to the Linux systems.

Any time we add/remove presentation of a vdisk to the host, we have to reboot the machine to get it to recognize the disks. hp_rescan (part of the fibreutils package) does not do what I thought it would...(clear all reference to the LUNS and rebuild it's memory of LUNS)

Any help on how to recognize disks without having to reboot?

Thanks,
Tom Callahan

[Steven Clementi]

Tom:


Have you tried unloading the hba driver and reloading it? It is better than restarting the server, but technically, you would lose access to all your vdisks while the driver is unloading and re-loading. Faster than a restart.


Steven

[Tom Callahan_1]

Unfortunately our current model relies on no physical disks being present, therefore, removing the module would kill the system.

Thanks,
Tom Callahan

[Steven Clementi]

I wonder if there is a way to reset a card individually. I know in Windows, in SAN Surfer, I think you can do this (thoough it is not necessary for scanning new devices). Maybe with the fibre utilities or SANSurfer you can stop one card at a time and restart it.


Steven

[Tom Callahan_1]

Another part of this question....

It appears the qlogic driver is limited to 32 LUNS per target path.

Any way to extend this to the regular 255?

Thanks,
Tom Callahan

[Urban Petry]

What about

echo "scsi add-single-device " >/proc/scsi/scsi

and

echo "scsi remove-single-device " >/proc/scsi/scsi

if you know the exact "location" of the device (which you should on EVAs because you present them to a specific LUN) or take a look at the script at http://www.garloff.de/kurt/linux/rescan-scsi-bus.sh or http://bash.cyberciti.biz/diskadmin/rescan-scsi-bus.sh.html (have not used any of them myself; the first one seems to be newer)

Urban

[Ivan Ferreira]

I use the rescan-scsi-bus.sh script and it works really good.

My recommendation is to use that script.

Cheers.

[SAKET_5]

Hi Tom,

what about probe-luns - a tool that is part of the HP FibreUtils package?