Adding SAN storage path

By | October 31, 2013

We know adding the local disk to the system is a very simple task. Adding local disk appears in output of fdisk -l command and logfile /var/log/messages.

This article is for the situation where Storage Server is Fibre Channel, I mean you need to use disk(LUN) available through SAN. In the case of Fibre Channel make note of WWNN (World Wide Node Name) of the storage server. Also determine is there single WWNN for all ports and if not also note WWPN (World Wide Port Name) for each port that will be used to access the new LUN.

Suppose you are in a situation where you have only one WWNN for all ports, then determine the

HBA number (h)
HBA Channel (c)
SCSI target id(t)

Remember that LUNs are available on SCSI target.

Suppose your WWNN is 50060070040004151 then

#grep 50060070040004151 /sys/class/fc_transport/*/node_name

This should produce output like

/sys/class/fc_transport/target5:0:2/node_name:50060070040004151
/sys/class/fc_transport/target5:0:3/node_name:50060070040004151

Here,

Channel number is 0
Storage Port is 2 and 3
HBA number is 5

So here if you have a LUN (Value 56), then following command add one path to that LUN

echo “0 2 56”>/sys/class/scsi_host/host5/scan

Similarly

echo “0 3 56”>/sys/class/scsi_host/host5/scan

Add another path.

OR

We can also use wildcard in place of channel,Port and LUN number to scan all paths,

echo “- – -“>/sys/class/scsi_host/host5/scan

Once scanning complete, execute following command to list all paths to storage device

#multipath -l

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