Friday, February 8, 2008

iSCSI and Qlogic tips....

env: RHEL4 U5
Equallogic SAN
Qlogic HBA 4050/4060

To add/remove/manage LUNS on Qlogic HBA the iscli command line tool is used. When you remove the LUNs using iscli utility, the disks related to these LUNs will be removed from the system. When you add new LUNs, you would need to reset the HBA to get the disks added to system. Sometimes you may not get the disks added even you reset the HBA with iscli utility, you might reboot the server.

To avoid the system reboot and get the disks added to system you can do the following:

1. Unload the qla4xxx module, which is used as driver for HBA.
# rmmod qla4xxx

2. Reload the qla4xxx module.
# modprobe qla4xxx

Note: Before doing this you should unmount all the mounted SAN filesystems cleanly. If you haven't unmounted the filesystems or filesystem is not unmounted cleanly, you will get error "qla4xxxx: module in use", when you try to unload the module.

# When you have multipathing configured, you would receive error "qla4xxxx: module in use", even you unmount the filesystems cleanly. This is because the multipath device mapper doesn't release the disk devices. In this case you need to flush the multipath configuration and then unload/load the qla4xxx module.
To flush the multipath maps use command below:
# multipath -f [map name]

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