Add New Multipath Block Device

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Adding a new LUN

Whenever you want to present a LUN to an active machine, you must either rescan the SCSI bus or restart the machine. Scanning the bus can be achieved with:

# echo "- - -" > /sys/class/scsi_host/hostX/scan

Replace the X with the SCSI bus you wish to scan. This is a non-destructive action, and so all buses may be scanned at any time.

Next, view the currently known multipaths with:

# multipath -ll

All connected SCSI disks, including the ones on any SAN paths, should now be shown. New devices will be shown as just a WWID, but we want to give each disk a personality to be able to recall them more accurately. To do this, we will create an alias in /etc/multipath.conf set to a friendlier name that has been communicated.

# vi /etc/multipath.conf

multipaths {
   multipath {
      wwid "3600508b40010889b00009000015a0000"
      alias system
   multipath {
      wwid "3600508b40010889b0000900001880000"
      alias data01

Reload the device map with:

# multipath -r

Now you have a new block device, you can proceed to convert it into a Physical Volume for LVM, or put a filesystem directly onto the block device.

Once done, create a mountpoint for this filesystem:

# mkdir /databases/data01

Set the correct permissions at the mount point:

# chown oracle:dba /databases/data01

# chmod 770 /databases/data01

# chmod +s /databases/data01

Edit /etc/fstab So that the filesystem will be mounted on boot:

# vi /etc/fstab

/dev/Vdata01/Ldata01 /databases/data01 ext4 defaults 1 2

Then you can test (and mount) this with:

# mount -a