LVM Logical Volume Manager
Deploy logical volume
Commonly used LVM deployment commands
| Function/Command | Physical volume management | Volume group management | Logical volume management |
| scanning | pvscan | vgscan | lvscan |
| set up | pvcreate | vgcreate | lvcreate |
| display | pvdisplay | vgdisplay | lvdisplay |
| delete | pvremove | vgremove | lvremove |
| Expand | vgextend | lvextend | |
| Zoom out | vgreduce | lvreduce |
Let the newly added two hard disk devices support LVM technology
[root@slave1 ~]# ll /dev/sd*
brw-rw----. 1 root disk 8, 0 Jan 24 18:53 /dev/sda
brw-rw----. 1 root disk 8, 1 Jan 24 18:53 /dev/sda1
brw-rw----. 1 root disk 8, 2 Jan 24 18:53 /dev/sda2
brw-rw----. 1 root disk 8, 16 Jan 24 18:53 /dev/sdb
brw-rw----. 1 root disk 8, 32 Jan 24 18:53 /dev/sdc
[root@slave1 ~]# pvcreate /dev/sdb /dev/sdc
Physical volume "/dev/sdb" successfully created.
Physical volume "/dev/sdc" successfully created.
[root@slave1 ~]#
Add two hard disk devices to the storage volume group, and then check the status of the volume group
[root@slave1 ~]# vgcreate storage /dev/sdb /dev/sdc
Volume group "storage" successfully created
[root@slave1 ~]# vgdisplay
--- Volume group ---
VG Name storage
System ID
Format lvm2
Metadata Areas 2
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 2
Act PV 2
VG Size 39.99 GiB
PE Size 4.00 MiB
Total PE 10238
Alloc PE / Size 0 / 0
Free PE / Size 10238 / 39.99 GiB
VG UUID z5j0JI-BSuO-IuYC-AK6i-Tnrx-OD4T-fpZ1qA
--- Volume group ---
VG Name rhel
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 1
Act PV 1
VG Size <59.00 GiB
PE Size 4.00 MiB
Total PE 15103
Alloc PE / Size 15103 / <59.00 GiB
Free PE / Size 0 / 0
VG UUID epIxAe-PdPy-19Wd-BL26-PViU-8fpc-bK3DJk
Cut out a logical volume device of about 150MB .
[root@slave1 ~]# lvcreate -n vo -L 150M storage
Rounding up size to full physical extent 152.00 MiB
Logical volume "vo" created.
[root@slave1 ~]# lvdisplay
--- Logical volume ---
LV Path /dev/storage/vo
LV Name vo
VG Name storage
LV UUID 4pldYD-2cRC-YnOO-KUfX-orvz-8fVr-YRYCEf
LV Write Access read/write
LV Creation host, time slave1, 2021-01-24 18:59:09 +0800
LV Status available
# open 0
LV Size 152.00 MiB
Current LE 38
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:3
--- Logical volume ---
LV Path /dev/rhel/swap
LV Name swap
VG Name rhel
LV UUID D81kEP-mLtB-sjFL-l086-KHpq-rEA4-1SSxq1
LV Write Access read/write
LV Creation host, time localhost, 2020-11-01 11:12:25 +0800
LV Status available
# open 2
LV Size <2.05 GiB
Current LE 524
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/rhel/home
LV Name home
VG Name rhel
LV UUID v8PBeR-sRyS-fN2c-s0gN-gXgL-aw80-uQNUCr
LV Write Access read/write
LV Creation host, time localhost, 2020-11-01 11:12:25 +0800
LV Status available
# open 1
LV Size 18.68 GiB
Current LE 4783
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
--- Logical volume ---
LV Path /dev/rhel/root
LV Name root
VG Name rhel
LV UUID 5x4xKG-nMMr-AnZM-mXGG-Tt8X-X2vs-In0w5r
LV Write Access read/write
LV Creation host, time localhost, 2020-11-01 11:12:26 +0800
LV Status available
# open 1
LV Size <38.27 GiB
Current LE 9796
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
[root@slave1 ~]#
Format the generated logical volume and mount it for use
[root@slave1 ~]# mkfs.ext4 /dev/storage/vo
mke2fs 1.44.3 (10-July-2018)
Creating filesystem with 155648 1k blocks and 38912 inodes
Filesystem UUID: b438efec-52d2-4cfe-930c-054b7ef1c09b
Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729
Allocating group tables: done
Writing inode tables: done
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done
[root@slave1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 969M 0 969M 0% /dev
tmpfs 984M 0 984M 0% /dev/shm
tmpfs 984M 9.6M 974M 1% /run
tmpfs 984M 0 984M 0% /sys/fs/cgroup
/dev/mapper/rhel-root 39G 4.1G 35G 11% /
/dev/mapper/rhel-home 19G 178M 19G 1% /home
/dev/sda1 1014M 153M 862M 15% /boot
tmpfs 197M 16K 197M 1% /run/user/42
tmpfs 197M 3.5M 194M 2% /run/user/1000
/dev/sr0 6.7G 6.7G 0 100% /run/media/linuxprobe/RHEL-8-0-0-BaseOS-x86_64
tmpfs 197M 4.0K 197M 1% /run/user/0
[root@slave1 ~]# mkdir /LVM_XX
[root@slave1 ~]# mount /dev/storage/vo /LVM_XX
[root@slave1 ~]# echo "/dev/storage/vo /LVM_XX ext4 defaults 0 0" >> /etc/fstab
[root@slave1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 969M 0 969M 0% /dev
tmpfs 984M 0 984M 0% /dev/shm
tmpfs 984M 9.6M 974M 1% /run
tmpfs 984M 0 984M 0% /sys/fs/cgroup
/dev/mapper/rhel-root 39G 4.1G 35G 11% /
/dev/mapper/rhel-home 19G 178M 19G 1% /home
/dev/sda1 1014M 153M 862M 15% /boot
tmpfs 197M 16K 197M 1% /run/user/42
tmpfs 197M 3.5M 194M 2% /run/user/1000
/dev/sr0 6.7G 6.7G 0 100% /run/media/linuxprobe/RHEL-8-0-0-BaseOS-x86_64
tmpfs 197M 4.0K 197M 1% /run/user/0
/dev/mapper/storage-vo 144M 1.6M 132M 2% /LVM_XX
[root@slave1 ~]# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sun Nov 1 11:12:31 2020
#
# Accessible filesystems, by reference, are maintained under '/dev/disk/'.
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info.
#
# After editing this file, run 'systemctl daemon-reload' to update systemd
# units generated from this file.
#
/dev/mapper/rhel-root / xfs defaults 0 0
UUID=a9745542-52aa-46e9-8559-c7eadd2e4b20 /boot xfs defaults 0 0
/dev/mapper/rhel-home /home xfs defaults 0 0
/dev/mapper/rhel-swap swap swap defaults 0 0
/dev/storage/vo /LVM_XX ext4 defaults 0 0
[root@slave1 ~]#
Expand logical volume
Extend the logical volume vo in the previous experiment to 290MB
[root@slave1 ~]# umount /LVM_XX
[root@slave1 ~]# lvextend -L 290M /dev/storage/vo
Rounding size to boundary between physical extents: 292.00 MiB.
Size of logical volume storage/vo changed from 152.00 MiB (38 extents) to 292.00 MiB (73 extents).
Logical volume storage/vo successfully resized.
[root@slave1 ~]#
Check the integrity of the hard drive and reset the hard drive capacity.
[root@slave1 ~]# e2fsck -f /dev/storage/vo
e2fsck 1.44.3 (10-July-2018)
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/storage/vo: 11/38912 files (0.0% non-contiguous), 10567/155648 blocks
[root@slave1 ~]# resize2fs /dev/storage/vo
resize2fs 1.44.3 (10-July-2018)
Resizing the filesystem on /dev/storage/vo to 299008 (1k) blocks.
The filesystem on /dev/storage/vo is now 299008 (1k) blocks long.Remount the hard disk device and check the mounting status
[root@slave1 ~]# mount -a
[root@slave1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 969M 0 969M 0% /dev
tmpfs 984M 0 984M 0% /dev/shm
tmpfs 984M 9.6M 974M 1% /run
tmpfs 984M 0 984M 0% /sys/fs/cgroup
/dev/mapper/rhel-root 39G 4.1G 35G 11% /
/dev/mapper/rhel-home 19G 178M 19G 1% /home
/dev/sda1 1014M 153M 862M 15% /boot
tmpfs 197M 16K 197M 1% /run/user/42
tmpfs 197M 3.5M 194M 2% /run/user/1000
/dev/sr0 6.7G 6.7G 0 100% /run/media/linuxprobe/RHEL-8-0-0-BaseOS-x86_64
tmpfs 197M 4.0K 197M 1% /run/user/0
/dev/mapper/storage-vo 279M 2.1M 259M 1% /LVM_XX
[root@slave1 ~]# Shrink logical volume
Check the integrity of the file system
[root@slave1 ~]# umount /LVM_XX
[root@slave1 ~]# e2fsck -f /dev/storage/vo
e2fsck 1.44.3 (10-July-2018)
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/storage/vo: 11/75776 files (0.0% non-contiguous), 15729/299008 blocks
[root@slave1 ~]# Reduce the capacity of the logical volume vo to 120MB.
[root@slave1 ~]# resize2fs /dev/storage/vo 120M
resize2fs 1.44.3 (10-July-2018)
Resizing the filesystem on /dev/storage/vo to 122880 (1k) blocks.
The filesystem on /dev/storage/vo is now 122880 (1k) blocks long.
[root@slave1 ~]# lvreduce -L 120M /dev/storage/vo
WARNING: Reducing active logical volume to 120.00 MiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce storage/vo? [y/n]: y
Size of logical volume storage/vo changed from 292.00 MiB (73 extents) to 120.00 MiB (30 extents).
Logical volume storage/vo successfully resized.
[root@slave1 ~]#
Remount the file system and view the system status
[root@slave1 ~]# mount -a
[root@slave1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 969M 0 969M 0% /dev
tmpfs 984M 0 984M 0% /dev/shm
tmpfs 984M 9.6M 974M 1% /run
tmpfs 984M 0 984M 0% /sys/fs/cgroup
/dev/mapper/rhel-root 39G 4.1G 35G 11% /
/dev/mapper/rhel-home 19G 178M 19G 1% /home
/dev/sda1 1014M 153M 862M 15% /boot
tmpfs 197M 16K 197M 1% /run/user/42
tmpfs 197M 3.5M 194M 2% /run/user/1000
/dev/sr0 6.7G 6.7G 0 100% /run/media/linuxprobe/RHEL-8-0-0-BaseOS-x86_64
tmpfs 197M 4.0K 197M 1% /run/user/0
/dev/mapper/storage-vo 113M 1.6M 103M 2% /LVM_XX
[root@slave1 ~]# Logical volume snapshot
First check the information of the volume group.
[root@slave1 ~]# vgdisplay
--- Volume group ---
VG Name storage
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 2
Act PV 2
VG Size 39.99 GiB
PE Size 4.00 MiB
Total PE 10238
Alloc PE / Size 30 / 120.00 MiB
Free PE / Size 10208 / <39.88 GiB
VG UUID z5j0JI-BSuO-IuYC-AK6i-Tnrx-OD4T-fpZ1qA
--- Volume group ---
VG Name rhel
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 1
Act PV 1
VG Size <59.00 GiB
PE Size 4.00 MiB
Total PE 15103
Alloc PE / Size 15103 / <59.00 GiB
Free PE / Size 0 / 0
VG UUID epIxAe-PdPy-19Wd-BL26-PViU-8fpc-bK3DJk
[root@slave1 ~]#
It can be clearly seen from the output information of the volume group that 10208 capacity has been used in the volume group, and there is still 39.88GB of free capacity. Next, use redirection to write a file to the directory mounted by the logical volume device
[root@slave1 ~]# echo "Welcome to Linuxprobe.com" > /LVM_XX/readme.txt
[root@slave1 ~]# ls -l /LVM_XX/readme.txt
-rw-r--r--. 1 root root 26 Jan 24 22:09 /LVM_XX/readme.txt
1. Use the -s parameter to generate a snapshot volume, and use the -L parameter to specify the size of the cut. In addition, you also need to write the snapshot operation for which logical volume is performed after the command
[root@slave1 /]# lvcreate -L 120M -s -n SNAP /dev/storage/vo
Logical volume "SNAP" created.
[root@slave1 /]# lvdisplay
--- Logical volume ---
LV Path /dev/storage/vo
LV Name vo
VG Name storage
LV UUID 4pldYD-2cRC-YnOO-KUfX-orvz-8fVr-YRYCEf
LV Write Access read/write
LV Creation host, time slave1, 2021-01-24 18:59:09 +0800
LV snapshot status source of
SNAP [active]
LV Status available
# open 1
LV Size 120.00 MiB
Current LE 30
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:3
--- Logical volume ---
LV Path /dev/storage/SNAP
LV Name SNAP
VG Name storage
LV UUID 78YABh-TEUM-YrY9-Tuei-WT2R-VoBT-5XU4Gx
LV Write Access read/write
LV Creation host, time slave1, 2021-01-24 21:52:43 +0800
LV snapshot status active destination for vo
LV Status available
# open 0
LV Size 120.00 MiB
Current LE 30
COW-table size 120.00 MiB
COW-table LE 30
Allocated to snapshot 0.01%
Snapshot chunk size 4.00 KiB
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:6
--- Logical volume ---
LV Path /dev/rhel/swap
LV Name swap
VG Name rhel
LV UUID D81kEP-mLtB-sjFL-l086-KHpq-rEA4-1SSxq1
LV Write Access read/write
LV Creation host, time localhost, 2020-11-01 11:12:25 +0800
LV Status available
# open 2
LV Size <2.05 GiB
Current LE 524
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/rhel/home
LV Name home
VG Name rhel
LV UUID v8PBeR-sRyS-fN2c-s0gN-gXgL-aw80-uQNUCr
LV Write Access read/write
LV Creation host, time localhost, 2020-11-01 11:12:25 +0800
LV Status available
# open 1
LV Size 18.68 GiB
Current LE 4783
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
--- Logical volume ---
LV Path /dev/rhel/root
LV Name root
VG Name rhel
LV UUID 5x4xKG-nMMr-AnZM-mXGG-Tt8X-X2vs-In0w5r
LV Write Access read/write
LV Creation host, time localhost, 2020-11-01 11:12:26 +0800
LV Status available
# open 1
LV Size <38.27 GiB
Current LE 9796
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
[root@slave1 /]#
2. Create a 100MB junk file in the directory where the logical volume is mounted, and then check the status of the snapshot volume. It can be found whether the usage of storage space has increased
[root@slave1 ~]# echo "Welcome to Linuxprobe.com" > /LVM_XX/readme.txt
[root@slave1 ~]# ls -l /LVM_XX/readme.txt
-rw-r--r--. 1 root root 26 Jan 24 22:09 /LVM_XX/readme.txt
[root@slave1 ~]# dd if=/dev/zero of=/LVM_XX/files count=1 bs=100M
1+0 records in
1+0 records out
104857600 bytes (105 MB, 100 MiB) copied, 1.18871 s, 88.2 MB/s
[root@slave1 ~]# lvdisplay
--- Logical volume ---
LV Path /dev/storage/vo
LV Name vo
VG Name storage
LV UUID iQ3yjL-T3A8-B52O-rsyf-WAQG-tty5-3GsCYM
LV Write Access read/write
LV Creation host, time slave1, 2021-01-24 22:02:43 +0800
LV snapshot status source of
SNAP [active]
LV Status available
# open 1
LV Size 120.00 MiB
Current LE 30
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:3
--- Logical volume ---
LV Path /dev/storage/SNAP
LV Name SNAP
VG Name storage
LV UUID 3N9S4y-lwbZ-IyPY-EklL-tuAW-iYfP-meWFQp
LV Write Access read/write
LV Creation host, time slave1, 2021-01-24 22:07:25 +0800
LV snapshot status active destination for vo
LV Status available
# open 0
LV Size 120.00 MiB
Current LE 30
COW-table size 120.00 MiB
COW-table LE 30
Allocated to snapshot 83.74%
Snapshot chunk size 4.00 KiB
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:6
--- Logical volume ---
LV Path /dev/rhel/swap
LV Name swap
VG Name rhel
LV UUID D81kEP-mLtB-sjFL-l086-KHpq-rEA4-1SSxq1
LV Write Access read/write
LV Creation host, time localhost, 2020-11-01 11:12:25 +0800
LV Status available
# open 2
LV Size <2.05 GiB
Current LE 524
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/rhel/home
LV Name home
VG Name rhel
LV UUID v8PBeR-sRyS-fN2c-s0gN-gXgL-aw80-uQNUCr
LV Write Access read/write
LV Creation host, time localhost, 2020-11-01 11:12:25 +0800
LV Status available
# open 1
LV Size 18.68 GiB
Current LE 4783
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
--- Logical volume ---
LV Path /dev/rhel/root
LV Name root
VG Name rhel
LV UUID 5x4xKG-nMMr-AnZM-mXGG-Tt8X-X2vs-In0w5r
LV Write Access read/write
LV Creation host, time localhost, 2020-11-01 11:12:26 +0800
LV Status available
# open 1
LV Size <38.27 GiB
Current LE 9796
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
[root@slave1 ~]#
3. In order to verify the effect of the SNAP snapshot volume, it is necessary to perform a snapshot restore operation on the logical volume. Before that, remember to unmount the logical volume device and the mounting of the directory: the snapshot volume will be automatically deleted, and the 100MB junk file created just after the logical volume device is snapshot is also cleared.
[root@slave1 ~]# umount /LVM_XX
[root@slave1 ~]# lvconvert --merge /dev/storage/SNAP
Merging of volume storage/SNAP started.
storage/vo: Merged: 29.03%
storage/vo: Merged: 100.00%
[root@slave1 ~]# ls -l /LVM_XX/
total 0
[root@slave1 ~]# Delete logical volume
Cancel the mounting association between the logical volume and the directory, delete the permanently effective device parameters in the configuration file, first umount /LVM_XX, and then delete the configuration in the configuration file
To delete a logical volume device , you need to enter y to confirm the operation
Delete the volume group, just write the volume group name here, the absolute path of the device is not required
Delete physical volume device
That is, the deletion order is the logical volume device, except the volume group, the physical volume device
