I’ve run into issues where the drive runs out of space and have to add a new one and move the data. Most of the time it scares me. I am going to documents steps for my own reference.
Volume management creates a layer of abstraction over physical storage, allowing us to create logical volumes. LVM creates logical volumes which can be extended and reduced, making it possible to add capacity or to remove capacity from a volume wherein the hardware storage configuration is hidden from the software. This will allows us to migrate a volume to a larger drives as it runs out of space. The underlying physical storage unit of an LVM logical volume is a block devices such as a partition or whole disk. You can span disks, migrate between disks and resize on the fly. LVM maps data in logical extents to physical extents on disk.
I am going to expand a volume onto a larger disk by creating a logical volume on one disk, move it to a larger disk and remove the small disk. Visual below shows the steps:
First we will create partition, pv, vg, lv and create a file that will fill up the first drive.
[root@localhost ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT fd0 2:0 1 4K 0 disk sda 8:0 0 15G 0 disk ├─sda1 8:1 0 1G 0 part /boot └─sda2 8:2 0 14G 0 part ├─cl-root 253:0 0 12.5G 0 lvm / └─cl-swap 253:1 0 1.5G 0 lvm [SWAP] sdb 8:16 0 20G 0 disk sdc 8:32 0 40G 0 disk sr0 11:0 1 1024M 0 rom
Currently, two disks 1)sdb 20GB and 2) sdc 40 GB. We will create lvm volume on 20G disk, fill up data and migrate it 40GB disk.
- On the physical volume sdb, create a partition using fidisk.
[root@localhost ~]# fdisk /dev/sdb Welcome to fdisk (util-linux 2.23.2).
hanges will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x4c29bd14.
The device presents a logical sector size that is smaller than
the physical sector size. Aligning to a physical sector (or optimal
I/O) size boundary is recommended, or performance may be impacted.
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): ^C
[root@localhost ~]# fdisk /dev/sdb 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.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xba3c5f20.
The device presents a logical sector size that is smaller than
the physical sector size. Aligning to a physical sector (or optimal
I/O) size boundary is recommended, or performance may be impacted.
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):
First sector (2048-41943039, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039):
Using default value 41943039
Partition 1 of type Linux and of size 20 GiB is set
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
2) Create PV (physical volume)
[root@localhost ~]# pvcreate /dev/sdb1 Physical volume "/dev/sdb1" successfully created.
pvscan to scan for physical volume (PV)
[root@localhost ~]# pvscan PV /dev/sda2 VG cl lvm2 [14.00 GiB / 0 free] PV /dev/sdb1 lvm2 [20.00 GiB] Total: 2 [34.00 GiB] / in use: 1 [14.00 GiB] / in no VG: 1 [20.00 GiB]
You can also use pvdisplay which will show in details.
root@localhost ~]# pvdisplay --- Physical volume --- PV Name /dev/sda2 VG Name cl PV Size 14.00 GiB / not usable 3.00 MiB Allocatable yes (but full) PE Size 4.00 MiB Total PE 3583 Free PE 0 Allocated PE 3583 PV UUID 1LayY5-cuk1-lCt5-T79u-7rw1-nHjN-0CFekY "/dev/sdb1" is a new physical volume of "20.00 GiB" --- NEW Physical volume --- PV Name /dev/sdb1 VG Name PV Size 20.00 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID oGgBUf-iHAW-NtAz-kTdW-tfC0-wvRx-NoumMk
3) Create VG (volume group) and give it a name.
[root@localhost ~]# vgcreate your_vg /dev/sdb1 Volume group "your_vg" successfully created [root@localhost ~]# vgscan Reading volume groups from cache. Found volume group "your_vg" using metadata type lvm2 Found volume group "cl" using metadata type lvm2 [root@localhost ~]# vgdisplay --- Volume group --- VG Name your_vg System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 1 VG Access read/write VG Status resizable MAX LV 0 Cur LV 0 Open LV 0 Max PV 0 Cur PV 1 Act PV 1 VG Size 20.00 GiB PE Size 4.00 MiB Total PE 5119 Alloc PE / Size 0 / 0 Free PE / Size 5119 / 20.00 GiB VG UUID 6emZe9-uGE6-aGz4-3gE4-4gON-c5ZO-UsPaqt --- Volume group --- VG Name cl System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 3 VG Access read/write VG Status resizable MAX LV 0 Cur LV 2 Open LV 2 Max PV 0 Cur PV 1 Act PV 1 VG Size 14.00 GiB PE Size 4.00 MiB Total PE 3583 Alloc PE / Size 3583 / 14.00 GiB Free PE / Size 0 / 0 VG UUID 7oDICk-mlgR-cmUJ-lffq-OwHH-4f7g-81UIdI
4) Create logical volume which will take all of the available space in the volume group.
root@localhost ~]# lvcreate -l 100%VG -n your_lv your_vg Logical volume "your_lv" created. [root@localhost ~]# lvscan ACTIVE '/dev/your_vg/your_lv' [20.00 GiB] inherit ACTIVE '/dev/cl/swap' [1.50 GiB] inherit ACTIVE '/dev/cl/root' [12.50 GiB] inherit [root@localhost ~]# lvdisplay --- Logical volume --- LV Path /dev/your_vg/your_lv LV Name your_lv VG Name your_vg LV UUID 30L7kM-5wgo-g9YR-Ozmf-nUom-2Yko-aoX8So LV Write Access read/write LV Creation host, time localhost.localdomain, 2020-01-20 13:28:46 -0500 LV Status available # open 0 LV Size 20.00 GiB Current LE 5119 Segments 1 Allocation inherit Read ahead sectors auto currently set to 8192 Block device 253:2
5) Create a File system
mke2fs 1.42.9 (28-Dec-2013)
Discarding device blocks: done
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1310720 inodes, 5241856 blocks
262092 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2153775104
160 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
6) Mount the file system
Create a folder
[root@localhost ~]# mkdir /mnt/lvm-disk mout the file system [root@localhost ~]# mount /dev/mapper/your_vg-your_lv /mnt/lvm-disk/ Check space [root@localhost lvm-disk]# df -h . Filesystem Size Used Avail Use% Mounted on /dev/mapper/your_vg-your_lv 20G 45M 19G 1% /mnt/lvm-disk
7) Allocate space, create 19GB file
mke2fs 1.42.9 (28-Dec-2013)
Discarding device blocks: done
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1310720 inodes, 5241856 blocks
262092 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2153775104
160 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This drive has no more space, so we are going to attach a new disk and move this file to sdbc of 40GB size.
1) Create a partition and save it.
sdc 8:32 0 40G 0 disk
[root@localhost lvm-disk]# 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.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x3a620a56.
The device presents a logical sector size that is smaller than
the physical sector size. Aligning to a physical sector (or optimal
I/O) size boundary is recommended, or performance may be impacted.
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):
First sector (2048-83886079, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-83886079, default 83886079):
Using default value 83886079
Partition 1 of type Linux and of size 40 GiB is set
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
2) Create a Physical Volume (PV)
[root@localhost ~]# pvcreate /dev/sdc1
3) Extend the volume group (VG) to include this PV (sdc1)
[root@localhost ~]# vgextend your_vg /dev/sdc1 Volume group "your_vg" successfully extended
4) Move data from one physical volume to another
Set the name, your volume group slash your logical volume, then specify which physical volume to move off of and which one to move the data onto.
[root@localhost ~]# pvmove -n your_vg/your_lv /dev/sdb1 /dev/sdc1 /dev/sdb1: Moved: 0.06% /dev/sdb1: Moved: 3.63% /dev/sdb1: Moved: 7.44% /dev/sdb1: Moved: 11.29% /dev/sdb1: Moved: 15.14% /dev/sdb1: Moved: 18.87% /dev/sdb1: Moved: 22.72% /dev/sdb1: Moved: 26.47% /dev/sdb1: Moved: 30.30% /dev/sdb1: Moved: 34.09% /dev/sdb1: Moved: 38.00% /dev/sdb1: Moved: 41.90% /dev/sdb1: Moved: 45.83% /dev/sdb1: Moved: 49.52% /dev/sdb1: Moved: 53.39% /dev/sdb1: Moved: 57.24% /dev/sdb1: Moved: 61.13% /dev/sdb1: Moved: 64.95% /dev/sdb1: Moved: 68.70% /dev/sdb1: Moved: 72.46% /dev/sdb1: Moved: 76.25% /dev/sdb1: Moved: 80.00% /dev/sdb1: Moved: 83.94% /dev/sdb1: Moved: 87.75% /dev/sdb1: Moved: 91.50% /dev/sdb1: Moved: 95.29% /dev/sdb1: Moved: 99.26% /dev/sdb1: Moved: 100.00%
5) Once the data has been moved from one physical volume to another,
Remove old physical volume from the volume group.
[root@localhost ~]# vgreduce your_vg /dev/sdb1 Removed "/dev/sdb1" from volume group "your_vg"
6) Remove the old physical volume from the physical disk.
[root@localhost ~]# pvremove /dev/sdb1 Labels on physical volume "/dev/sdb1" successfully wiped.
7) Extend the logical volume to take up all of the space of the new drive.
[root@localhost ~]# lvextend -l 100%VG /dev/mapper/your_vg-your_lv Size of logical volume your_vg/your_lv changed from 20.00 GiB (5119 extents) to 40.00 GiB (10239 extents). Logical volume your_vg/your_lv successfully resized.
8) Extend the size of the file system to take up the space available in the logical volume, we will need to unmount it. Run e2fsck on the local volume to check everything is ok.
[root@localhost ~]# e2fsck /dev/mapper/your_vg-your_lv e2fsck 1.42.9 (28-Dec-2013) /dev/mapper/your_vg-your_lv: clean, 12/1310720 files, 4764995/5241856 blocks check everthing is ok. [root@localhost ~]# e2fsck -f /dev/mapper/your_vg-your_lv e2fsck 1.42.9 (28-Dec-2013) Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information /dev/mapper/your_vg-your_lv: 12/1310720 files (0.0% non-contiguous), 4764995/5241856 blocks [root@localhost ~]# resize2fs /dev/mapper/your_vg-your_lv resize2fs 1.42.9 (28-Dec-2013) Resizing the filesystem on /dev/mapper/your_vg-your_lv to 10484736 (4k) blocks. The filesystem on /dev/mapper/your_vg-your_lv is now 10484736 blocks long. mount it back [root@localhost ~]# mount /dev/mapper/your_vg-your_lv /mnt/lvm-disk/ [root@localhost ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/cl-root 13G 950M 12G 8% / devtmpfs 446M 0 446M 0% /dev tmpfs 457M 0 457M 0% /dev/shm tmpfs 457M 6.1M 451M 2% /run tmpfs 457M 0 457M 0% /sys/fs/cgroup /dev/sda1 1014M 138M 877M 14% /boot tmpfs 92M 0 92M 0% /run/user/0 /dev/mapper/your_vg-your_lv 40G 18G 20G 48% /mnt/lvm-disk
File system has more space and resides on larger disk.
