Renaming an LVM logical volume group.
Show all the volume groups on the system:
sudo vgdisplayRename the volume group:
sudo vgrename [old name] [new name]Double check the volume groups again to make sure the change went through:
sudo vgdisplayEdit the fstab to reflect the logical volume name change. Note that if the volume group name has a - in it, it needs to be doubled in the fstab. So a volume group named sandbox-vg would need to be sandbox--vgin the fstab:
sudo nano /etc/fstabUpdate the GRUB bootloader to get the new logical volume name recognized:
sudo update-grub2The update the existing initramfs stuff like this:
sudo update-initramfs -uCreating a new LVM physical and logical volume group.
Creating the physical volume.
Use lsblk to see a list of all connected block level devices; in this example we are acting on /dev/sdb:
lsblkCreate the physical volume on /dev/sdb for the new LVM like this:
sudo pvcreate /dev/sdbNext run pvscan to get a short list of physical volumes connected to the the machine:
sudo pvscanThe output should be something like this:
PV /dev/sda5 VG sandbox-vg lvm2 [31.76 GiB / 0 free]
PV /dev/sdb lvm2 [8.00 GiB]
Total: 2 [39.76 GiB] / in use: 1 [31.76 GiB] / in no VG: 1 [8.00 GiB]Or run pvdisplay to get deeper information on the physical volumes:
sudo pvdisplayNow let’s create a new logical volume group called test_group like this:
sudo vgcreate test_group /dev/sdbThe response from that should be something like this:
Volume group "test_group" successfully createdAnd if you run pvscan again:
sudo pvscanThe output should be something like this:
PV /dev/sdb VG test_group lvm2 [8.00 GiB / 8.00 GiB free]
PV /dev/sda5 VG sandbox-vg lvm2 [31.76 GiB / 0 free]
Total: 2 [39.75 GiB] / in use: 2 [39.75 GiB] / in no VG: 0 [0 ]Creating the logical volume.
Now let’s create the logical volume like so:
sudo lvcreate -L 8G -n test_volume test_groupIf that command fails with an error like this:
Insufficient free extents (2047) in volume group test_group: 2048 requiredTry running this command:
sudo lvcreate -l2047 -n test_volume test_groupCheck the list of logical volumes like so:
sudo lvscanThe list should look something like this:
ACTIVE '/dev/test_group/test_volume' [8.00 GiB] inherit
ACTIVE '/dev/sandbox-vg/root' [27.76 GiB] inherit
ACTIVE '/dev/sandbox-vg/swap_1' [4.00 GiB] inheritYou can remove a logical volume like so:
sudo lvremove /dev/test_group/test_volumeCreating file system and on the logical volume and mounting.
Knowing the device is located at /dev/test_group/test_volume let’s format it as ext3 like this:
sudo mkfs -t ext3 /dev/test_group/test_volumeAfter that is done, the device should be formatted and ready to mount. Let’s create a test mount point called mount_test:
sudo mkdir -p ~/mount_test/Now let’s manually mount the device to the mount point like this:
sudo mount /dev/test_group/test_volume ~/mount_test/If the device mounted, you should be returned cleanly to the command prompt. To see if it is mounted, just check the output of mount -l or df -h to see it there. Here is an example of some df -h output:
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/sandbox--vg-root 28G 2.8G 24G 11% /
udev 2.0G 4.0K 2.0G 1% /dev
tmpfs 396M 356K 395M 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 2.0G 0 2.0G 0% /run/shm
/dev/sda1 236M 36M 188M 16% /boot
/dev/mapper/test_group-test_volume 7.8G 19M 7.4G 1% /home/sysop/mount_testAnd finally to make that volume mount automatically on system start, we need to edit the fstab like this:
sudo nano /etc/fstabAnd add this; note the device name of /dev/test_group/test_volume as well as the mount point of /home/sysop/mount_test in addition to the format type indicated as ext3:
/dev/test_group/test_volume /home/sysop/mount_test ext3 defaults,nodev,nosuid,nobootwait 0 0Now if the machine is stopped and restarted or simply rebooted, the volume will automatically be mounted without any additional work.
To unmount the volume, run this command:
sudo umount /home/sysop/mount_testAdding a disk to an LVM logical volume group.
Before anything, make sure the LVM volume is unmounted by running a command like this:
sudo umount /home/sysop/mount_testOnce that is unmounted, use lsblk to see a list of all connected block level devices; in this example we are acting on /dev/sdc:
lsblkCreate the physical volume for the new LVM like this:
sudo pvcreate /dev/sdcResponse should be something like this:
Physical volume "/dev/sdc" successfully createdNow get your volume group name with vgdisplay like this:
sudo pvscanIn this case let’s assume the volume group name is test_group. So now let’s add the disk to the existing volume group using vgextend like this:
sudo vgextend test_group /dev/sdcThe response should be something like this:
Volume group "test_group" successfully extendedNext, let’s actually extend the test_volume with the full contents of /dev/sdc:
sudo lvextend /dev/test_group/test_volume /dev/sdcThen run this e2fsck command like this to scan the filesystem:
sudo e2fsck -f /dev/test_group/test_volumeAnd finally resize the filesystem like this:
sudo resize2fs /dev/test_group/test_volumeNow, remount /dev/test_group/test_volume to ~/mount_test/ like this:
sudo mount /dev/test_group/test_volume ~/mount_test/And once remounted, the new added space will be reflected in it’s expanded size; here is an example of some df -houtput:
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/sandbox--vg-root 28G 2.8G 24G 11% /
udev 2.0G 4.0K 2.0G 1% /dev
tmpfs 396M 356K 395M 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 2.0G 0 2.0G 0% /run/shm
/dev/sda1 236M 36M 188M 16% /boot
/dev/mapper/test_group-test_volume 16G 23M 15G 1% /home/sysop/mount_testSundry LVM debugging stuff.
If somehow you need to reduce the size of a volume group—by getting rid of all unused disks—run this command:
sudo vgreduce test_group -aOr if you want to remove a disk from a logical volume, first run this command to remove the logical volume:
sudo lvremove /dev/test_group/test_volumeAnd then run this vgreduce command:
sudo vgreduce test_group /dev/sdcCheck the current UUID:
sudo blkid -c /dev/null