Advanced Topic

Warning - this is an advanced topic. Always backup your data first.

Preparation

Add a new disk to both machines of EXACTLY the same size and configuration in the virtual environment.

It is also possible to use a new partition on an existing disk whose size has been increased, but this is not covered here.

The commands below assume that /dev/sdc will be used to increase the size of the storage in a DRBD on top of LVM configuration.

Rescan the SCSI Bus to display the drive

Sometimes the system will not see the new disk immediately. To achieve this without a reboot, run the following command to rescan the SCSI bus.

Rescan SCSI Bus
# Check if the disk is there
ls /dev/sd*
 
# Expected output (includes /dev/sdc)
/dev/sda  /dev/sda1  /dev/sda2  /dev/sdb  /dev/sdc
 
# If not, rescan SCSI and repeat above
echo "- - -" > /sys/class/scsi_host/host0/scan


Make one node Secondary

Determine which node is servicing the SMB share with pcs status, and then on the non sevicing node:

# Determine which node is servicing the share
pcs status
 
# Standby the server on which the resources are NOT running
pcs cluster standby acd-store2
 
# Run this command on the STANDBY machine
drbdadm secondary jtelshared

Create LVM Physical Volume, Extend the Volume Group and the Logical Volume (Both Nodes)

# Create the phsyical volume - this is based on sdc assuming it is the third drive on the system
lvm pvcreate /dev/sdc

# Extend the volume group
lvm vgextend "vg_drbd_jtelshared" /dev/sdc

# Create the logical volume
lvm lvresize -l +100%FREE /dev/vg_drbd_jtelshared/lv_drbd_jtelshared

Extend the DRBD Resource (Primary Node Only)

# Extend the DRBD resource
drbdadm -- --assume-clean resize jtelshared

Resize the FileSystem (Primary Node Only)

# Resize File System
xfs_growfs /dev/drbd/by-res/jtelshared/0

Make Secondary Node Primary and Unstandby in Cluster (Secondary Node Only)

# Back to primary
drbdadm primary jtelshared
 
# Back to unstandby
pcs cluster unstandby acd-store2

Check the Results (Primary Node Only)

df -h



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