Devices

To configure the newly added LUNS on RHEL:

 ls /sys/class/fc_host
 host0  host1  host2  host3

 fdisk -l 2>/dev/null | egrep '^Disk' | egrep -v 'dm-' | wc -l

 echo "1" > /sys/class/fc_host/host0/issue_lip

 echo "- - -" > /sys/class/scsi_host/host0/scan

 echo "1" > /sys/class/fc_host/host1/issue_lip

 echo "- - -" > /sys/class/scsi_host/host1/scan

 echo "1" > /sys/class/fc_host/host2/issue_lip

 echo "- - -" > /sys/class/scsi_host/host2/scan

 echo "1" > /sys/class/fc_host/host3/issue_lip

 echo "- - -" > /sys/class/scsi_host/host3/scan

 cat /proc/scsi/scsi | egrep -i 'Host:' | wc -l

 fdisk -l 2>/dev/null | egrep '^Disk' | egrep -v 'dm-' | wc -l

Alternatively, we can run the re-scan-scsi script.

To scan new LUNs on Linux operating system which is using QLogic driver
You need to find out driver proc file /proc/scsi/qlaXXX. For example on my system it is /proc/scsi/qla2300/0
Once file is identified you need to type following command (login as the root user):

 # echo "scsi-qlascan" > /proc/scsi/qla2300/0
 # cat /proc/scsi/qla2300/0

Now use the script rescan-scsi-bus.sh new LUN as a device. Run script as follows:

 # ./rescan-scsi-bus.sh -l -w

Download the script from here

The output of ls -l /sys/block/*/device should give you an idea about how each device is connected to the system.

How to differentiate local storage from SAN LUN

In the example below red is a virtual disk on an internal RAID controller, green is a CD-ROM connected via an IDE controller, and the rest are SAN-connected SCSI disks where "hostN" refers to the instance of the Host Bus Adapter they are connected to.

 # ls -l /sys/block/*/device
 lrwxrwxrwx  1 root root 0 Sep 19 02:11 /sys/block/cciss!c0d0/device -> ../../devices/pci0000:00/0000:00:04.0/0000:0d:00.0/disk0
 lrwxrwxrwx  1 root root 0 Sep 19 02:11 /sys/block/hda/device -> ../../devices/pci0000:00/0000:00:1f.1/ide0/0.0
 lrwxrwxrwx  1 root root 0 Sep 18 14:58 /sys/block/sda/device -> ../../devices/pci0000:00/0000:00:02.0/0000:13:00.0/host0/target0:0:0/0:0:0:0
 lrwxrwxrwx  1 root root 0 Sep 18 14:58 /sys/block/sdb/device -> ../../devices/pci0000:00/0000:00:02.0/0000:13:00.0/host0/target0:0:0/0:0:0:1
 lrwxrwxrwx  1 root root 0 Sep 18 14:58 /sys/block/sdc/device -> ../../devices/pci0000:00/0000:00:02.0/0000:13:00.0/host0/target0:0:0/0:0:0:64
 lrwxrwxrwx  1 root root 0 Sep 18 14:58 /sys/block/sdd/device -> ../../devices/pci0000:00/0000:00:02.0/0000:13:00.0/host0/target0:0:0/0:0:0:120
 ...