Using LVM to resize partitions

1. problem

Before using Windows I think it's amazing that I can adjust the partition size at will , Feeling Linux You should be able to adjust the partition size at will , But does the tool in the built-in graphical interface have the ability to change the partition size . To study the lvm I realized that I had to use the terminal lvm Tools can adjust the size of partitions

2. Main process

First of all, understand PV（Physical）、VG（Volume Group）、LV（Logic Volume） These three concepts .

PV（ Physical volume ） Represents the partition on the actual disk , That is to use gdisk、fdisk Partition out of partition .

VG Express PV Partition group composed of , Multiple PV Of storage space VG Storage space of , here VG It's like a new disk .

LV It means that VG Logical partition on disk .

LV When used, it is a virtual disk partition , Can be used to mount .LV The most important difference from a normal physical partition is LV It can be resized , Partitions of ordinary disks cannot be resized . except LV It can be resized VG You can also adjust the size , Just go VG Add a new physical volume to the .

So create LV The process is as follows ：

2.1 gdisk Stage

gdisk First create three new physical volumes on the disk , as follows . Last three Linux filesystem Is the newly created physical partition .

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048         1230847   600.0 MiB   EF00  EFI System Partition
   2         1230848         3327999   1024.0 MiB  8300  
   3         3328000        55764991   25.0 GiB    8E00  
   4        55764992        57862143   1024.0 MiB  8300  Linux filesystem
   5        57862144        58886143   500.0 MiB   8300  Linux filesystem
   6        58886144        59910143   500.0 MiB   8300  Linux filesystem

About such as The contents of any physical partition

2.2 PV Stage

PV The phase is a bit like the format of the physical partition phase ,gdisk After partitioning, you only need to use the following instructions to create on the physical partition PV that will do .

$ pvcreate /dev/sda{
    4,5,6}
Physical volume "/dev/sda4" successfully created.
Physical volume "/dev/sda5" successfully created.
Physical volume "/dev/sda6" successfully created.

Then use the command pvscan View the created partition （ The display will have a 25G Of PV, That was created when I installed the system ）

$ pvscan
PV /dev/sda3   VG fedora_localhost-live   lvm2 [25.00 GiB / 7.00 GiB free]
PV /dev/sda4                              lvm2 [1.00 GiB]
PV /dev/sda5                              lvm2 [500.00 MiB]
PV /dev/sda6                              lvm2 [500.00 MiB]
Total: 4 [<26.98 GiB] / in use: 1 [25.00 GiB] / in no VG: 3 [<1.98 GiB]

2.3 VG Stage

VG The stage is to create the previously created PV Add a newly created （ Or old ）VG.

Use vgcreate Creating VG Join in at the same time PV

$ vgcreate vg  /dev/sda4 /dev/sda5 /dev/sda6
  Volume group "vg" successfully created

Once created, you can use vgreduce Delete one PV; Or use vgextend Add one PV. In this way, adjustment can be achieved VG The purpose of size .

$ vgreduce vg /dev/sda5
  Removed "/dev/sda5" from volume group "vg"
$ vgextend vg /dev/sda5
  Volume group "vg" successfully extended

2.4 LV Stage

And then finally in the VG Create logical partitions on LV.

Use lvcreate Create logical partitions , among -L Specify the size of the partition ,-n Specify the name of the logical partition .

$ lvcreate -L 500M -n first_lv vg
  Logical volume "first_lv" created.

The next step is to /dev/vg/first_lv Find the logical partition just separated on the . Then you can use the normal steps to format 、 mount .

$ mkfs.ext4 /dev/vg/first_lv
$ mkdir /media/logical1
$ mount /dev/vg/first_lv /media/logical1
$ df -Th /media/logical1
Filesystem              Type  Size  Used Avail Use% Mounted on
/dev/mapper/vg-first_lv ext4  477M  2.3M  445M   1% /media/logical1

2.5 Resize partition

Expand first first_lv The capacity of , Use lvresize

$ lvresize -L +500M /dev/vg/first_lv 
  Size of logical volume vg/first_lv changed from 500.00 MiB (125 extents) to 1000.00 MiB (250 extents).
  Logical volume vg/first_lv successfully resized.

Successful expansion first_lv The partition cannot be expanded until the partition is unmounted （ There should be a way not to uninstall , But we haven't found it yet ）

$ umount /media/logical1/
$ e2fsck -f /dev/vg/first_lv
$ resize2fs /dev/vg/first_lv
$ mount /dev/vg/first_lv /media/logical1/
$ df -Th /media/logical1/
Filesystem              Type  Size  Used Avail Use% Mounted on
/dev/mapper/vg-first_lv ext4  961M  2.5M  905M   1% /media/logical1

After mounting, you can see that the capacity of the file system has indeed increased to 1000M.

To reduce the use of file systems lvresize. However, according to the above method of extending the file system, I directly destroyed the file system , So a new one is created 1000M Of first_lv, In another way, it is reduced to 500M.

$ umount /media/logical1
$ lvresize --resizefs --size 500M /dev/vg/fist_lv
fsck from util-linux 2.35.2
/dev/mapper/vg-fist_lv: clean, 11/64000 files, 8748/256000 blocks
resize2fs 1.45.5 (07-Jan-2020)
Resizing the filesystem on /dev/mapper/vg-fist_lv to 128000 (4k) blocks.
The filesystem on /dev/mapper/vg-fist_lv is now 128000 (4k) blocks long.

  Size of logical volume vg/fist_lv changed from 1000.00 MiB (250 extents) to 500.00 MiB (125 extents).
  Logical volume vg/fist_lv successfully resized.
$ mount /dev/vg/fist_lv /media/logical1/
$ df -Th /media/logical1/
Filesystem             Type  Size  Used Avail Use% Mounted on
/dev/mapper/vg-fist_lv ext4  477M  1.5M  440M   1% /media/logical1