This documentation shows how to migrate existing logical volumes to other new drives without any downtime. Before moving further, I would like to give some useful information about Logical Volume Management(LVM). There are two ways to migrate an LVMs’ storage unit.
- LVM Mirroring
- LVM Pvmove
LVM Mirroring Methods:
Step 1:Check new device which ‘ll be used after migration
New Disk ID:/dev/sdd
Next command is optional:Just we create a new partition
#fdisk /dev/sdd n,p,1,enter,enter
Step 2:Check LVM device which you need to migrate
#vgdisplay vghitachi #lvdisplay -v /dev/vghitachi/lvhitachi
“You should check LVM size before get new LUN device. Your LUN device size must be bigger then total LVM size.”
Step 3:Create PV with new added LUN device
Step 4:Extend VG with new added PV
#vgextend vghitachi /dev/sdd1
Step 5:Add new mirror device to LVM.
#lvconvert -m 1 –corelog /dev/vghitachi/lvhitachi /dev/sdd1
Step 6:Remove old disk from LVM.
Before remove old disk from LVM you need to check mirror state with “lvdisplay -v” or “lvs -o+devices” command.
#lvconvert -m 0 /dev/vghitachi/lvhitachi /dev/emcpowere1
Step 7:Remove old pv from Volume Group(vg).
#vgreduce vghitachi /dev/emcpowere1
Step 8:Remove old pv
LVM PvMove Method:
Instead using ‘lvconvert’ mirroring command, you can use ‘pvmove‘ command with option ‘-n‘ (logical volume name) method to mirror data between two pv device.
Step 1-2-3 are same as Mirroring Method
Step 4:Move Pv from old device to new device
#pvmove -n /dev/vghitachi/lvhitachi /dev/sdd1 /dev/emcpowere1
This command is one of the simple way to mirror data between two pv.But we strongly advice LVM mirroring Method instead of pvmove.