The post discusses on how to expand the space available in an LVM volume by extending the physical disk partition using fdisk. This example shows how to resize the physical volume /dev/sdc1 from 200MB to 400MB.
Check the current configuration
1. Check the current size of the physical volume on the disk.
# pvdisplay /dev/sdc1 "/dev/sdc1" is a new physical volume of "200.00 MiB" --- NEW Physical volume --- PV Name /dev/sdc1 VG Name PV Size 200.00 MiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID EkD95A-wb04-5GHn-OH7N-suVt-vak2-AKSsyv
2. Get the information about the current LVM setup. The logical volume which we want to extend is ‘testlv’.
# lvscan ACTIVE '/dev/testvg/testlv' [100.00 MiB] inherit
Deactivate the existing logical volume
1. Before we proceed with the actual PV and LV expansion, we must deactivate the logical volume first. Use the below command to deactivate the LV.
# lvchange -a n /dev/testvg/testlv
2. Verify if the volume has been deactivated.
# lvscan inactive '/dev/testvg/testlv' [100.00 MiB] inherit
Now we know the LVM is not being used, so we can start the expansion process on it.
Extend the partition “/dev/sda1” with fdisk utility
1. In order to extend the physical device partition information, we first delete the old partition and then create a new one. Note that we first print out the current partition information so that we know precisely where the partition starts. We must overlay the new, larger partition beginning at the same block as the old partition.
# fdisk /dev/sdc
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): p
Disk /dev/sdc: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x085579f4
Device Boot Start End Blocks Id System
/dev/sdc1 2048 411647 204800 83 Linux
Command (m for help): d
Selected partition 1
Partition 1 is deleted
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-41943039, default 2048): ### we will press ENTER here to select default first sector 2048
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +400M
Partition 1 of type Linux and of size 400 MiB is set
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks. This step can be aborted at any time prior to writing out the altered partition table with the “w” command. Until then, only an in-memory copy of the partition table is altered.
Load the new partition table to kernel
The currently-running kernel is not aware of the new partition information, since fdisk alters the partition table by writing directly to the device. Normally, the kernel only reads partition information at system boot or when a hot-plug event (such as inserting a USB device) occurs.
However, we can avoid a needless reboot by causing the kernel to re-read its partition information, and then to update its LVM information.
# partprobe
Now that the kernel is aware of the updated partition table, inform the LVM subsystem about this change to the physical device. By default the resize will use the entire partition size as obtained from the partition table:
# pvresize /dev/sdc1 Physical volume "/dev/sdc1" changed 1 physical volume(s) resized / 0 physical volume(s) not resized
# pvdisplay /dev/sdc1 --- Physical volume --- PV Name /dev/sdc1 VG Name testvg PV Size 399.00 MiB / not usable 3.00 MiB Allocatable yes PE Size 4.00 MiB Total PE 99 Free PE 74 Allocated PE 25 PV UUID EkD95A-wb04-5GHn-OH7N-suVt-vak2-AKSsyv
Active the existing logical volume
The final step is to bring the modified LVM back on-line. As always, we check our work first:
# lvscan ACTIVE '/dev/testvg/testlv' [100.00 MiB] inherit
As seen from the output above, the logical volume is inactive. So lets activate it first.
# lvchange -a y /dev/testvg/testlv
# /usr/sbin/lvscan ACTIVE '/dev/vgtest/lvtest' [100.00 MB] inherit
Resizing the Logical Volume (optional)
1. You can now also extend the logical volume as you have more space in the underlying physical volume now. Use the command below to resize the LV.
# lvresize -L +200M /dev/testvg/testlv Size of logical volume testvg/testlv changed from 100.00 MiB (25 extents) to 300.00 MiB (75 extents). Logical volume testvg/testlv successfully resized.
2. Verify the new sise of the logical volume.
# lvscan ACTIVE '/dev/testvg/testlv' [300.00 MiB] inherit