Add 4 multipath LUNs into RHEL

1. SSH to oracle-node1 and run the following commands:

# echo "- - -" > /sys/class/scsi_host/host3/scan
# echo "- - -" > /sys/class/scsi_host/host4/scan
# service multipathd reload
# multipath -ll

Look for output from the multipath -ll command similar to what is listed below:

mpath30 (360060e801038f270057f59f70000000e) dm-30 HITACHI,DF600F
mpath31 (360060e801038f270057f59f70000000d) dm-31 HITACHI,DF600F
mpath32 (360060e801038f270057f59f70000000e) dm-32 HITACHI,DF600F
mpath33 (360060e801038f270057f59f70000000e) dm-33 HITACHI,DF600F

2. Make a backup copy of the existing /etc/multipath.conf file by running the following command listed below:

# cp /etc/multipath.conf /etc/multipath.conf-backup

3. Edit /etc/multipath.conf and create a device mapper alias for the following LUN as listed below:

vol 0124 DG3_1
vol 0125 DG3_2
vol 0126 DG3_3
vol 0127 DG3_4

Example syntax:

multipath {
wwid 360060e80104b3ab004f322b300000001
alias DG3_1
}
multipath {
wwid 360060e80104b3ab004f322b300000001
alias DG3_2
}
multipath {
wwid 360060e80104b3ab004f322b300000001
alias DG3_3
}
multipath {
wwid 360060e80104b3ab004f322b300000001
alias DG3_4
}

Replace the WWID in the example syntax listed above with the correct WWID from the output of multipath -ll obtained in step 1.

4. Run the command 'service multipathd reload' and verify the new devices appear in the /dev/mapper directory (DG3_1, DG3_2, DG3_3, DG3_4)

# service multipathd reload
# ls /dev/mapper

5. Label and partition the disk for ASM use

# parted /dev/mapper/DG3_1
mklabel msdos
mkpart pri
63
25g
Exit

Repeat step 5 for /dev/mapper/DG3_2
Repeat step 5 for /dev/mapper/DG3_3
Repeat step 5 for /dev/mapper/DG3_4

6. We need to repeat step1-5 on oracle-node2
7. If necessary, run the command
partprobe /dev/mapper/DG3_1
partprobe /dev/mapper/DG3_2
partprobe /dev/mapper/DG3_3
partprobe /dev/mapper/DG3_4