Adding new disk/LUN under multipath Linux mpath.

Suppose we want to add a new disk where multipath is configured.

Lets add a 20Gb LUN and set up it under multipath on server.

Create vg_products volume group on with /oracledba filesystem.


1. Ask storage team to export LUN to the system and take the UUID of the SAN disk(s) presented.


2. Scan for the new disks

echo "- - -" > /sys/class/scsi_host/host0/scan
echo "- - -" > /sys/class/scsi_host/host1/scan
echo "- - -" > /sys/class/scsi_host/host2/scan


3. Now use multipath to search for your UUID.

# multipath -l | grep -i X00507680C8084XX5800000000000XXX 
mpathao (3X00507680C8084XX5800000000000XXX) dm-51 IBM ,2145


4. Now define an alias so that we can create our PV.

# vi /etc/multipath.conf

# Add below in appropriate place:
multipath {
wwid 3600507680c8084395800000000000117
alias mpath_NGEcop_redo
multipath {
wwid 3X00507680C8084XX5800000000000XXX
alias mpath_oracledba

Please note lowercase letters, and the UUID needs a “3” in front.


5. Restart multipathd daemon

# systemctl restart multipathd


6. Check if new multipath identified.> multipath -l | grep -i X00507680C8084XX5800000000000XXX
mpath_oracledba (3X00507680C8084XX5800000000000XXX) dm-51 IBM ,2145


7. Create new physical volume from this mpath.

# pvcreate /dev/mapper/mpath_oracledba


8. Create new Volume

Edit /etc/lvm/lvm.conf to tell it this volume group needs to be trated as a LOCAL one.

In case this server is in cluster, we have to tell it that the filesystem is local.

# vi /etc/lvm.conf
volume_list = [ "vg_NGEL051", "vg_NGEcop_backup", "vg_NGEcop_data", "vg_NGEcop_oracle", "vg_NGEcop_redo", "vg_hmpre_oracle", "vg_hmpreprd_hm_back", "vg_hmpreprd_hm_data", "vg_hmpreprd_hm_redo", "vg_soahmpre_back", "vg_soahmpre_data", "vg_soahmpre_redo", "vg_products" ]


9. Create new logical volume and mount it on system.

### Create new LV.
# lvcreate -l 100%FREE -n lv_oracledba vg_products

### Format the volume
# mkfs -t ext4 /dev/mapper/vg_products-lv_oracledba

# Create mount point and change its permissions.
# mkdir /oracledba ; chmod 775 /oracledba

# vi /etc/fstab and add the required line.
/dev/mapper/vg_products-lv_oracledba /oracledba ext4 defaults 1 2

### Mount the partition
# mount /oracledba

### Change ownership
# chown orahmpre:oinstall /oracledba
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