UCC has an EMC SAN connected over fibre channel. This page documents a couple of handy commands and other dos/don'ts. For initial setup and config, see SANConfig in wheel docs.

Scanning for new LUNs

for i in $(ls -1 /sys/class/scsi_host/); do echo '- - -' > /sys/class/scsi_host/$i/scan; done

Removing a LUN from a host

• Ensure the device is unmounted on the host
• Delete the LUN on the SAN

• Use multipath -ll to list the device maps, dm names and path status. The device you're removing should have all paths as "failed", otherwise you're probably looking at the wrong device.

• By default, the failure mode of a device is to queue data if the device becomes unavailable. This prevents the device being removed from multipath because there's usually data in the queue. To delete the device, you first have to set it to fail if there's no path with the following command on the host:

dmsetup message <dm name, eg dm-2> 0 "fail_if_no_path"

• Use multipath -ll to check that the mode has changed for the device

• You should then be able to remove the device with

multipath -f <device map, eg 3600601609fe010006cf4f3c6ef4ce21>