LVM logic volume details

LVM: Logical Volume Manager allows easy to operate abstraction layer of volumes, including resizing the file system, reorganizing the file system among multiple physical devices, and increasing the scalability (data loss will be caused if the mount has to be cancelled)

The difference between logical partition and logical volume

Logical volume and logical partition are not the same concept, and the capacity of logical partition cannot be changed; the capacity of logical volume can be changed (based on logical volume above physical volume and volume group); logical volume manager (LVM) can manage disk space more easily (consolidated disk pool)

Here is the schematic diagram for better understanding

#Create physical volume 

pvcreate /dev/sda3 

\#Assign physical volumes to volume groups 

vgcreate vg0 /dev/sda3 

\#Create a logical volume from a volume group 

lvcreate  -L 256M  -n data vg0 

\#mkfs.xfs   /dev/vg0/data 
//Create file system

\#mount 

mount /dev/vg0/data /mnt/data#
extend

lvextend -L [+]#[mMgGtT] /dev/VG_NAME/LV_NAME 

\#Aiming at ext 

resize2fs /dev/VG_NAME/LV_NAME 

\#Aiming at xfs  

xfs_growfs MOUNTPOINT  

lvresize -r -l +100%FREE /dev/VG_NAME/LV_NAME
Reduction only supported ext4
umount /dev/VG_NAME/LV_NAME 

e2fsck -f /dev/VG_NAME/LV_NAME 

resize2fs /dev/VG_NAME/LV_NAME #[mMgGtT] 

lvreduce -L [-]#[mMgGtT] /dev/VG_NAME/LV_NAME 

mount 

It can be a hard disk or a partition. It needs to be changed

Example: create logical partition and extended partition for ext4

[root@27 ~]#fdisk -l /dev/sdb

Disk /dev/sdb: 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: 0x2d890684

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048     4196351     2097152   82  Linux swap / Solaris
/dev/sdb2         4196352     8390655     2097152   83  Linux #modify file type
[root@27 ~]#fdisk /dev/sdb2
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 0x59eb2927.

Command (m for help): t
No partition is defined yet!

Command (m for help): q

[root@27 ~]#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.


Command (m for help): t
Partition number (1,2, default 2): 2
Hex code (type L to list all codes): L

 0  Empty           24  NEC DOS         81  Minix / old Lin bf  Solaris        
 1  FAT12           27  Hidden NTFS Win 82  Linux swap / So c1  DRDOS/sec (FAT-
 2  XENIX root      39  Plan 9          83  Linux           c4  DRDOS/sec (FAT-
 3  XENIX usr       3c  PartitionMagic  84  OS/2 hidden C:  c6  DRDOS/sec (FAT-
 4  FAT16 <32M      40  Venix 80286     85  Linux extended  c7  Syrinx         
 5  Extended        41  PPC PReP Boot   86  NTFS volume set da  Non-FS data    
 6  FAT16           42  SFS             87  NTFS volume set db  CP/M / CTOS / .
 7  HPFS/NTFS/exFAT 4d  QNX4.x          88  Linux plaintext de  Dell Utility   
 8  AIX             4e  QNX4.x 2nd part 8e  Linux LVM       df  BootIt         
 9  AIX bootable    4f  QNX4.x 3rd part 93  Amoeba          e1  DOS access     
 a  OS/2 Boot Manag 50  OnTrack DM      94  Amoeba BBT      e3  DOS R/O        
 b  W95 FAT32       51  OnTrack DM6 Aux 9f  BSD/OS          e4  SpeedStor      
 c  W95 FAT32 (LBA) 52  CP/M            a0  IBM Thinkpad hi eb  BeOS fs        
 e  W95 FAT16 (LBA) 53  OnTrack DM6 Aux a5  FreeBSD         ee  GPT            
 f  W95 Ext d (LBA) 54  OnTrackDM6      a6  OpenBSD         ef  EFI (FAT-12/16/
10  OPUS            55  EZ-Drive        a7  NeXTSTEP        f0  Linux/PA-RISC b
11  Hidden FAT12    56  Golden Bow      a8  Darwin UFS      f1  SpeedStor      
12  Compaq diagnost 5c  Priam Edisk     a9  NetBSD          f4  SpeedStor      
14  Hidden FAT16 <3 61  SpeedStor       ab  Darwin boot     f2  DOS secondary  
16  Hidden FAT16    63  GNU HURD or Sys af  HFS / HFS+      fb  VMware VMFS    
17  Hidden HPFS/NTF 64  Novell Netware  b7  BSDI fs         fc  VMware VMKCORE 
18  AST SmartSleep  65  Novell Netware  b8  BSDI swap       fd  Linux raid auto
1b  Hidden W95 FAT3 70  DiskSecure Mult bb  Boot Wizard hid fe  LANstep        
1c  Hidden W95 FAT3 75  PC/IX           be  Solaris boot    ff  BBT            
1e  Hidden W95 FAT1 80  Old Minix      
Hex code (type L to list all codes): 8e (Change to Linux LVM)
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): p

Disk /dev/sdb: 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: 0x2d890684

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048     4196351     2097152   82  Linux swap / Solaris
/dev/sdb2         4196352     8390655     2097152   8e  Linux LVM  #Found modified

Command (m for help): w #Preservation
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
//Add a hard disk scan
[root@27 ~]#for i in {0..32};do echo '- - -' >/sys/class/scsi_host/host$i/scan;done
[root@27 ~]#lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0  200G  0 disk 
├─sda1   8:1    0    1G  0 part /boot
├─sda2   8:2    0  100G  0 part /
├─sda3   8:3    0    2G  0 part [SWAP]
├─sda4   8:4    0    1K  0 part 
└─sda5   8:5    0   50G  0 part /data
sdb      8:16   0   20G  0 disk 
├─sdb1   8:17   0    2G  0 part [SWAP]
└─sdb2   8:18   0    2G  0 part 
sdc      8:32   0    5G  0 disk  #This is this piece.
sr0     11:0    1 1024M  0 rom 
[root@27 ~]#pvcreate /dev/sd{b2,c} creates a physical volume
  Physical volume "/dev/sdb2" successfully created.
  Physical volume "/dev/sdc" successfully created.
[root@27 ~]#pvs viewing physical volumes
  PV         VG Fmt  Attr PSize PFree
  /dev/sdb2     lvm2 ---  2.00g 2.00g
  /dev/sdc      lvm2 ---  5.00g 5.00g
[root@27 ~]#pvdisplay view details
  "/dev/sdb2" is a new physical volume of "2.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb2
  VG Name               
  PV Size               2.00 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               jmJ13J-XHgq-ou2J-QVvB-CXy1-FTYX-8mnC5r
   
  "/dev/sdc" is a new physical volume of "5.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdc
  VG Name                              Empty
  PV Size               5.00 GiB
  Allocatable           NO
  PE Size               0             PE Size not specified by volume group
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               IQ0xHD-btaL-XmmT-cE9Q-BQMU-kYA2-ZDUZxQ
[root@27 ~]#vgcreate vg1 /dev/sd{b2,c}    
#######Vgcreate - s 16m Vg1 / dev / SD {B2, C} - s can specify PE size
  Volume group "vg1" successfully created
[root@27 ~]#vgs
  VG  #PV #LV #SN Attr   VSize VFree
  vg1   2   0   0 wz--n- 6.99g 6.99g
[root@27 ~]#pvs
  PV         VG  Fmt  Attr PSize  PFree 
  /dev/sdb2  vg1 lvm2 a--  <2.00g <2.00g
  /dev/sdc   vg1 lvm2 a--  <5.00g <5.00g
[root@27 ~]#vgdisplay
  --- Volume group ---
  VG Name               vg1
  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               6.99 GiB
  PE Size               4.00 MiB
  Total PE              1790
  Alloc PE / Size       0 / 0   
  Free  PE / Size       1790 / 6.99 GiB
  VG UUID               OBZcYO-20eN-m2E6-bDn8-ZUCg-Pfro-7caBik
[root@27 ~]#lvcreate -n shuju -l 100%free vg1 allocate all space selectively
  Logical volume "shuju" created.
[root@27 ~]#lvdisplay
  --- Logical volume ---
  LV Path                /dev/vg1/shuju   #Name of the logical volume
  LV Name                shuju
  VG Name                vg1
  LV UUID                zKB4qu-XMnJ-U4Qx-2IlZ-XRT6-f7km-m6mB9q
  LV Write Access        read/write
  LV Creation host, time 27, 2020-01-04 14:47:28 +0800
  LV Status              available
  # open                 0
  LV Size                6.99 GiB
  Current LE             1790
  Segments               2
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:,
[root@27 ~]#Mkfs.ext4/dev/vg1/shuju create file system
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
458752 inodes, 1832960 blocks
91648 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1876951040
56 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

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
[root@27 ~]#blkid
/dev/sda1: UUID="b09c53db-dbe8-4932-ad6e-2b0890ea8844" TYPE="xfs" 
/dev/sda2: UUID="703b7b55-0dc1-40fc-bfc5-e9a581c48a05" TYPE="xfs" 
/dev/sda3: UUID="16ba9174-387a-4725-8cdf-e67c7a52d3bc" TYPE="swap" 
/dev/sda5: UUID="b944d856-d1ac-4694-8c59-04399a8b4786" TYPE="xfs" 
/dev/sdb1: UUID="95565861-5268-4482-bf6d-349a97322559" TYPE="swap" 
/dev/sdb2: UUID="jmJ13J-XHgq-ou2J-QVvB-CXy1-FTYX-8mnC5r" TYPE="LVM2_member" 
/dev/sdc: UUID="IQ0xHD-btaL-XmmT-cE9Q-BQMU-kYA2-ZDUZxQ" TYPE="LVM2_member" 
/[root@27 ~]#mount /dev/vg1/shuju /mnt/shuju
[root@27 ~]#mkdir /mnt/shuju
[root@27 ~]#df
Filesystem            1K-blocks    Used Available Use% Mounted on
devtmpfs                1919944       0   1919944   0% /dev
tmpfs                   1930684       0   1930684   0% /dev/shm
tmpfs                   1930684   11908   1918776   1% /run
tmpfs                   1930684       0   1930684   0% /sys/fs/cgroup
/dev/sda2             104806400 1500324 103306076   2% /
/dev/sda5              52403200   32992  52370208   1% /data
/dev/sda1               1038336  144220    894116  14% /boot
tmpfs                    386140       0    386140   0% /run/user/0
/dev/mapper/vg1-shuju   7085560   32208   6670376   1% /mnt/shuju
/mapper/vg1-shuju: UUID="4e49d747-9616-418f-b66a-c07f41a0de98" TYPE="ext4" 
#Write to / etc/fstab to mount permanently
[root@27 ~]#vgextend vg1 /dev/sdb3 extended logical volume
  Physical volume "/dev/sdb3" successfully created.
  Volume group "vg1" successfully extended
[root@27 ~]#pvs
  PV         VG  Fmt  Attr PSize    PFree   
  /dev/sdb2  vg1 lvm2 a--    <2.00g       0 
  /dev/sdb3  vg1 lvm2 a--  1020.00m 1020.00m
  /dev/sdc   vg1 lvm2 a--    <5.00g       0 
[root@27 ~]#df -h
Filesystem             Size  Used Avail Use% Mounted on
devtmpfs               1.9G     0  1.9G   0% /dev
tmpfs                  1.9G     0  1.9G   0% /dev/shm
tmpfs                  1.9G   12M  1.9G   1% /run
tmpfs                  1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/sda2              100G  1.5G   99G   2% /
/dev/sda5               50G   33M   50G   1% /data
/dev/sda1             1014M  141M  874M  14% /boot
tmpfs                  378M     0  378M   0% /run/user/0
/dev/mapper/vg1-shuju  6.8G   32M  6.4G   1% /mnt/shuju See
[root@27 ~]#lvextend -r -L +500M /dev/vg1/shuju plus 500M
  Size of logical volume vg1/shuju changed from 6.99 GiB (1790 extents) to 7.48 GiB (1915 extents).
  Logical volume vg1/shuju successfully resized.
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/mapper/vg1-shuju is mounted on /mnt/shuju; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/mapper/vg1-shuju is now 1960960 blocks long.
[root@27 ~]#df -h 
Filesystem             Size  Used Avail Use% Mounted on
devtmpfs               1.9G     0  1.9G   0% /dev
tmpfs                  1.9G     0  1.9G   0% /dev/shm
tmpfs                  1.9G   12M  1.9G   1% /run
tmpfs                  1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/sda2              100G  1.5G   99G   2% /
/dev/sda5               50G   33M   50G   1% /data
/dev/sda1             1014M  141M  874M  14% /boot
tmpfs                  378M     0  378M   0% /run/user/0
/dev/mapper/vg1-shuju  7.3G   32M  6.9G   1% /mnt/shuju   Compared with the above, the space increases
#######Delete lvm logical volume
[root@27 ~]#lvremove /dev/vg1/shuju
Do you really want to remove active logical volume vg1/shuju? [y/n]: y Prompt whether to delete
  Logical volume "shuju" successfully removed
  [root@27 ~]#vgdisplay
  --- Volume group ---
  VG Name               vg1
  System ID             
  Format                lvm2
  Metadata Areas        3
  Metadata Sequence No  10
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                3
  Act PV                3
  VG Size               <7.99 GiB
  PE Size               4.00 MiB
  Total PE              2045
  Alloc PE / Size       0 / 0   
  Free  PE / Size       2045 / <7.99 GiB
  VG UUID               OBZcYO-20eN-m2E6-bDn8-ZUCg-Pfro-7caBik
   
[root@27 ~]#vgremove vg1 deleting a volume group
  Volume group "vg1" successfully removed
  [root@27 ~]#pvs
  PV         VG Fmt  Attr PSize PFree
  /dev/sdb2     lvm2 ---  2.00g 2.00g
  /dev/sdb3     lvm2 ---  1.00g 1.00g
  /dev/sdc      lvm2 ---  5.00g 5.00g
[root@27 ~]#pvremove /dev/sd{b2,b3,c} delete logical volumes
  Labels on physical volume "/dev/sdb2" successfully wiped.
  Labels on physical volume "/dev/sdb3" successfully wiped.
  Labels on physical volume "/dev/sdc" successfully wiped.
[root@27 ~]#fdisk -l /dev/sdb

Disk /dev/sdb: 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: 0x2d890684

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048     4196351     2097152   82  Linux swap / Solaris
/dev/sdb2         4196352     8390655     2097152   8e  Linux LVM  #It can also be deleted
/dev/sdb3         8390656    10487807     1048576   83  Linux
/dev/sdb4        10487808    12584959     1048576   83  Linux

Logical volume snapshot

Snapshot is a special logical volume. It is the exact copy of the logical volume that exists when the snapshot is generated. For the temporary copy of existing data and other operations that need to be backed up or copied, snapshot is the most appropriate choice. Only when they are different from the original logical volume, will the snapshot consume space. The volume size of the established snapshot is less than or equal to the original logical volume. You can also use lvextend Extended snapshot
Logical volume manager snapshot
Snapshot is to record the system information at that time, just like photographing. If any data changes in the future, the original data will be moved to the snapshot area, and the unchanged area will be shared by the snapshot area and the file system
How logical volume snapshots work
A certain amount of space will be allocated to the snapshot when it is generated, but only when the original logical volume or snapshot has changed will these spaces be used. When the original logical volume has changed, the old data will be copied to the snapshot. The snapshot only contains the changed data in the original logical volume or the changed data in the snapshot since the snapshot was generated. Because the snapshot area and the original L V shares many PE blocks, so the snapshot and the LV to be snapshot must be in the same VG. When the system recovers, the number of files cannot be higher than the actual capacity of the snapshot area

#Create a snapshot for an existing logical volume snapshot size is less than or equal to the logical volume size snapshot includes attribute backups

lvcreate -l 64 -s -n data-snapshot -p r /dev/vg0/data 

\#Mount snapshot 

mkdir  -p /mnt/snap 

mount -o ro /dev/vg0/data-snapshot   /mnt/snap 

\#Restore snapshot 

umount /dev/vg0/data-snapshot 

umount /dev/vg0/data 

lvconvert --merge /dev/vg0/data-snapshot  

\#Delete snapshot 

umount /mnt/databackup 

lvremove /dev/vg0/databackup
Snapshot example
[root@27 ~]#df -h
Filesystem             Size  Used Avail Use% Mounted on
devtmpfs               1.9G     0  1.9G   0% /dev
tmpfs                  1.9G     0  1.9G   0% /dev/shm
tmpfs                  1.9G   12M  1.9G   1% /run
tmpfs                  1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/sda2              100G  1.5G   99G   2% /
/dev/sda5               50G   33M   50G   1% /data
/dev/sda1             1014M  141M  874M  14% /boot
tmpfs                  378M     0  378M   0% /run/user/0
/dev/mapper/vg1-shuju  7.3G   32M  6.9G   1% /mnt/shuju
[root@27 ~]#cp /etc/fstab /mnt/shuju/f1
[root@27 ~]#cp /etc/fstab /mnt/shuju/f2
[root@27 ~]#cp /etc/fstab /mnt/shuju/f3
[root@27 ~]#ls /mnt/shuju
f1  f2  f3  lost+found
[root@27 ~]#lvcreate -n shuju_snapshot -s -p r -L 300M /dev/vg1/shuju
##### -n specified name - s snapshot r read only
  Logical volume "shuju_snapshot" created.
[root@27 ~]#lvdisplay
  --- Logical volume ---
  LV Path                /dev/vg1/shuju
  LV Name                shuju
  VG Name                vg1
  LV UUID                zKB4qu-XMnJ-U4Qx-2IlZ-XRT6-f7km-m6mB9q
  LV Write Access        read/write
  LV Creation host, time 27, 2020-01-04 14:47:28 +0800
  LV snapshot status     source of
                         shuju_snapshot [active]   Show with snapshot
  LV Status              available
  # open                 1
  LV Size                7.48 GiB
  Current LE             1915
  Segments               3
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0
   
  --- Logical volume ---
  LV Path                /dev/vg1/shuju_snapshot
  LV Name                shuju_snapshot   snapshot
  VG Name                vg1
  LV UUID                G8n4yi-FOkw-RlbZ-GtEf-8IHh-4fRw-hYnoma
  LV Write Access        read only   Read-only attribute
  LV Creation host, time 27, 2020-01-04 15:39:49 +0800
  LV snapshot status     active destination for shuju  Backup of data
  LV Status              available
  # open                 0
  LV Size                7.48 GiB
  Current LE             1915
  COW-table size         300.00 MiB
  COW-table LE           75
  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           253:3
[root@27 ~]#mkdir /mnt/snap
root@27 ~]#mount /dev/vg1/shuju_snapshot /mnt/snap
mount: /dev/mapper/vg1-shuju_snapshot is write-protected, mounting read-only
[root@27 ~]#ls /mnt/snap/
f1  f2  f3  lost+found  Visual deception. The data you see is not here
[root@27 ~]#df
Filesystem                     1K-blocks    Used Available Use% Mounted on
devtmpfs                         1919940       0   1919940   0% /dev
tmpfs                            1930680       0   1930680   0% /dev/shm
tmpfs                            1930680   11904   1918776   1% /run
tmpfs                            1930680       0   1930680   0% /sys/fs/cgroup
/dev/sda2                      104806400 1499084 103307316   2% /
/dev/sda5                       52403200   32992  52370208   1% /data
/dev/sda1                        1038336  144348    893988  14% /boot
tmpfs                             386140       0    386140   0% /run/user/0
/dev/mapper/vg1-shuju            7589336   32220   7153988   1% /mnt/shuju
/dev/mapper/vg1-shuju_snapshot   7589336   32220   7153988   1% /mnt/snap
[root@27 ~]#echo > /mnt/shuju/f1
[root@27 ~]#ll /mnt/shuju
total 28
-rw-r--r--. 1 root root     1 Jan  4 15:57 f1  Data emptying
-rw-r--r--. 1 root root   689 Jan  4 15:30 f2
-rw-r--r--. 1 root root   689 Jan  4 15:30 f3
drwx------. 2 root root 16384 Jan  4 14:54 lost+found
[root@27 ~]#ll /mnt/snap/f1
-rw-r--r--. 1 root root 689 Jan  4 15:30 /mnt/snap/f1  View data in snapshot
[root@27 ~]#rm -f /mnt/shuju/f2 delete f2
[root@27 ~]#ll /mnt/shuju/
total 24
-rw-r--r--. 1 root root     1 Jan  4 15:57 f1
-rw-r--r--. 1 root root   689 Jan  4 15:30 f3
drwx------. 2 root root 16384 Jan  4 14:54 lost+found
[root@27 ~]#ll /mnt/snap snapshot still exists
total 28
-rw-r--r--. 1 root root   689 Jan  4 15:30 f1
-rw-r--r--. 1 root root   689 Jan  4 15:30 f2
-rw-r--r--. 1 root root   689 Jan  4 15:30 f3
drwx------. 2 root root 16384 Jan  4 14:54 lost+found
[root@27 ~]#umount /mnt/shuju
[root@27 ~]#umount /mnt/snap
[root@27 ~]#Lvconvert -- merge / dev / Vg1 / Shuju? Snapshot
  Merging of volume vg1/shuju_snapshot started.
  vg1/shuju: Merged: 100.00%
[root@27 ~]#mount /dev/vg1/shuju /mnt/shuju
[root@27 ~]#ls /mnt/shuju
f1  f2  f3  lost+found
//Note: if the snapshot is used up in one time, it will be gone
If sdb2 It's going to break
[root@27 ~]#pvs
  PV         VG  Fmt  Attr PSize    PFree  
  /dev/sdb2  vg1 lvm2 a--    <2.00g      0 
  /dev/sdb3  vg1 lvm2 a--  1020.00m 520.00m
  /dev/sdc   vg1 lvm2 a--    <5.00g      0 
[root@27 ~]#pvdisplay
  --- Physical volume ---
  PV Name               /dev/sdb2
  VG Name               vg1
  PV Size               2.00 GiB / not usable 4.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              511
  Free PE               0
  Allocated PE          511
  PV UUID               jmJ13J-XHgq-ou2J-QVvB-CXy1-FTYX-8mnC5r
   
  --- Physical volume ---
  PV Name               /dev/sdc
  VG Name               vg1
  PV Size               2.00 GiB / not usable 4.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              511
  Free PE               0
  Allocated PE          511
  PV UUID               IQ0xHD-btaL-XmmT-cE9Q-BQMU-kYA2-ZDUZxQ
   
  --- Physical volume ---
  PV Name               /dev/sdb3
  VG Name               vg1
  PV Size               5.00 GiB / not usable 4.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              1279
  Free PE               1154 We found that there are 1154 more PE
  Allocated PE          125
  PV UUID               RGQEM5-1beD-BzaI-I1Pq-gng4-aUJZ-lEKlrP
[root@27 ~]#pvmove /dev/sdc moves the PE of sdb2 to other places (whatever space is available)
Removed "/dev/sdb2" from volume group "vg1"
[root@27 ~]#pvdisplay /dev/sdbc
  --- Physical volume ---
  PV Name               /dev/sdc
  VG Name                           You can see that it doesn't belong to any vg Space will be reduced accordingly
  PV Size               2.00 GiB 
  Allocatable           NO
  PE Size               0
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               jmJ13J-XHgq-ou2J-QVvB-CXy1-FTYX-8mnC5r
[root@27 ~]#pvs
  PV         VG  Fmt  Attr PSize    PFree  
  /dev/sdb2  vg1 lvm2 a--    <2.00g      0 
  /dev/sdb3  vg1 lvm2 a--  1020.00m 520.00m
  /dev/sdc        lvm2 a--    <5.00g      0 
  [root@27 ~]#pvremove /dev/sdc can be removed and the partition can be directly unplugged and deleted
 
volume ---
  PV Name               /dev/sdc
  VG Name                           You can see that it doesn't belong to any vg Space will be reduced accordingly
  PV Size               2.00 GiB 
  Allocatable           NO
  PE Size               0
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               jmJ13J-XHgq-ou2J-QVvB-CXy1-FTYX-8mnC5r
[root@27 ~]#pvs
  PV         VG  Fmt  Attr PSize    PFree  
  /dev/sdb2  vg1 lvm2 a--    <2.00g      0 
  /dev/sdb3  vg1 lvm2 a--  1020.00m 520.00m
  /dev/sdc        lvm2 a--    <5.00g      0 
  [root@27 ~]#pvremove /dev/sdc can be removed and the partition can be directly unplugged and deleted
  
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Keywords: snapshot Linux Vmware less

Added by krraleigh on Sat, 11 Jan 2020 12:51:00 +0200