Dynamically rescan LUN’s on SLES

I’m sure this is kids play to most people, but I’ve just not done much SAN work with Linux.

We bought a new EMC CLARiiON CX4-240, and I was just tossing it random LUN’s to do speed & HA tests. When I added a LUN I’d see it in powermt, and I didn’t know what the equivalent of devfsadm was in Linux … SLES to be specific. What can I say, I worked with Solaris way too long.

The first step is to run: powermt display

# powermt display
CLARiiON logical device count=3
================================================
—– Host Bus Adapters ——— —— I/O Paths —– —— Stats ——
### HW Path Summary Total Dead IO/Sec Q-IOs Errors
================================================
3 qla2xxx optimal 6 0 – 0 0
4 qla2xxx optimal 6 0 – 0 0

Note the 3/4 preceding the HBA’s.

Now, execute this:

# echo “- – -” > /sys/class/scsi_host/host3/scan
# echo “- – -” > /sys/class/scsi_host/host4/scan

Its my understand this also works on RHEL and others, but YMMV. This is all buried in the PowerPath manual too, but hopefully I’ve saved someone a bit of time.

Till next time…