Virtual machine LVM volume expansion actual operation
Article Directory
One, LVM
LVM is the abbreviation of Logical Volume Manager. It is a mechanism for managing disk partitions in the Linux environment. LVM is a logical layer built on hard disks and partitions to improve the flexibility of disk partition management Sex. LVM is a logical layer added between the disk partition and the file system to shield the lower layer disk partition layout for the file system, provide an abstract volume, and establish a file system on the volume. Physical volume (physical volume) refers to a hard disk partition or a device that logically has the same function as a disk partition (such as RAID). It is the basic storage logical block of LVM, but is not compatible with basic physical storage media (such as partitions, disks, etc.). ) Comparison, but it contains management parameters related to LVM.
Structure : The entire LVM structure is divided into: "physical volume, physical volume partition, volume group, logical volume", let me explain these four structures in detail below:
Physical Volume : Physical Volume, referred to as PV, a physical volume is just a physical storage medium with LVM management data added to it. To use the LVM system, first initialize the disk to be used for LVM. The purpose of initialization is to identify the disk or partition as a physical volume of LVM. Use the pvcreate command to mark a disk as an LVM physical volume.
Physical Partition : Physical Extents, PE for short, LVM calls each physical volume an addressable storage unit of a physical partition. The size of the storage unit is usually a few MB. The beginning part of the disk is the LVM metadata, and then starting from the index of zero, the index of each physical partition is incremented by one, and the allocation is performed in order.
Volume group : Volume Group, VG for short, physical volumes can be organized into volume groups. A volume group can consist of one or more physical volumes, and there can be multiple volume groups in the system. After the volume group is created, the volume group (not the disk) is the entity that represents the data storage. Therefore, although disks were moved from one system to another in the past, after using LVM, the volume group will be moved from one system to another. For this reason, it is often convenient to create multiple volume groups on a system.
Logical partition : Logical Extents, referred to as LE, the basic allocation unit of a logical volume is called a logical partition. The logical partition is mapped to the physical partition. Therefore, if the size of the physical partition is as small as 4MB, the size of the logical partition will also be 4MB. The size of the logical volume depends on the number of logical partitions allocated.
2. Actual operation
Scenario: Extend the existing disk space of the virtual machine.
[root@localhost ~]# cat /etc/redhat-release
CentOS Linux release 7.6.1810 (Core)
1. vmware increases storage space for virtual machines
Before expansion
[root@localhost ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 47G 2.0G 45G 5% /
devtmpfs devtmpfs 903M 0 903M 0% /dev
tmpfs tmpfs 915M 0 915M 0% /dev/shm
tmpfs tmpfs 915M 9.4M 906M 2% /run
tmpfs tmpfs 915M 0 915M 0% /sys/fs/cgroup
/dev/sda1 xfs 1014M 146M 869M 15% /boot
tmpfs tmpfs 183M 0 183M 0% /run/user/0
[root@localhost ~]# fdisk -l
Disk /dev/sda: 53.7 GB, 53687091200 bytes, 104857600 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: 0x000ad192
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 104857599 51379200 8e Linux LVM
Disk /dev/mapper/centos-root: 50.5 GB, 50457477120 bytes, 98549760 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 /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 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
- Extended operation
Turn off the virtual machine-Settings-Hard Disk (SCSI)-Expand!
After expansion (increase by 10G)
Note : As a result of the execution of fdisk -l, the space has increased by about 10G, but there is no change in df -hT at this time.
[root@localhost ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 47G 2.1G 45G 5% /
devtmpfs devtmpfs 903M 0 903M 0% /dev
tmpfs tmpfs 915M 0 915M 0% /dev/shm
tmpfs tmpfs 915M 9.3M 906M 2% /run
tmpfs tmpfs 915M 0 915M 0% /sys/fs/cgroup
/dev/sda1 xfs 1014M 146M 869M 15% /boot
tmpfs tmpfs 183M 0 183M 0% /run/user/0
[root@localhost ~]# fdisk -l
Disk /dev/sda: 64.4 GB, 64424509440 bytes, 125829120 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: 0x000ad192
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 104857599 51379200 8e Linux LVM
Disk /dev/mapper/centos-root: 50.5 GB, 50457477120 bytes, 98549760 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 /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 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
2. Create partition
Description :
m-help
n-new partition
t-modify the partition type (the same as the original, both are 8e, representing Linux LVM)
w-save
q-exit
[root@localhost ~]# fdisk /dev/sda
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): m
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
g create a new empty GPT partition table
G create an IRIX (SGI) partition table
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)
Command (m for help): p
Disk /dev/sda: 64.4 GB, 64424509440 bytes, 125829120 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: 0x000ad192
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 104857599 51379200 8e Linux LVM
Command (m for help): n
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p):
Using default response p
Partition number (3,4, default 3):
First sector (104857600-125829119, default 104857600):
Using default value 104857600
Last sector, +sectors or +size{K,M,G} (104857600-125829119, default 125829119):
Using default value 125829119
Partition 3 of type Linux and of size 10 GiB is set
Command (m for help): p
Disk /dev/sda: 64.4 GB, 64424509440 bytes, 125829120 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: 0x000ad192
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 104857599 51379200 8e Linux LVM
/dev/sda3 104857600 125829119 10485760 83 Linux
Command (m for help): t
Partition number (1-3, default 3): 3
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
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): p
Disk /dev/sda: 64.4 GB, 64424509440 bytes, 125829120 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: 0x000ad192
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 104857599 51379200 8e Linux LVM
/dev/sda3 104857600 125829119 10485760 8e Linux LVM
Command (m for help): w
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.
[root@localhost ~]# partprobe
Warning: Unable to open /dev/sr0 read-write (Read-only file system). /dev/sr0 has been opened read-only.
[root@localhost ~]# reboot
3. Create a physical volume
Note :
The Allocatable of /dev/sda3 is NO, and the PE Size is 0
[root@localhost ~]# pvdisplay
--- Physical volume ---
PV Name /dev/sda2
VG Name centos
PV Size <49.00 GiB / not usable 3.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 12543
Free PE 1
Allocated PE 12542
PV UUID 9X3qlf-viCH-Cymx-D1eI-vKdd-Ua14-F4bweF
[root@localhost ~]# pvcreate /dev/sda3
Physical volume "/dev/sda3" successfully created.
[root@localhost ~]# pvdisplay
--- Physical volume ---
PV Name /dev/sda2
VG Name centos
PV Size <49.00 GiB / not usable 3.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 12543
Free PE 1
Allocated PE 12542
PV UUID 9X3qlf-viCH-Cymx-D1eI-vKdd-Ua14-F4bweF
"/dev/sda3" is a new physical volume of "10.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sda3
VG Name
PV Size 10.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID dR5sDM-j21d-xGiB-32WH-xhe4-Sa96-t03jtb
4. Expand the volume group
[root@localhost ~]# vgdisplay
--- Volume group ---
VG Name centos
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 <49.00 GiB
PE Size 4.00 MiB
Total PE 12543
Alloc PE / Size 12542 / 48.99 GiB
Free PE / Size 1 / 4.00 MiB
VG UUID 682d9M-yRsn-60BJ-cY7f-nAVI-WA24-KmnhD1
[root@localhost ~]# vgextend centos /dev/sda3
Volume group "centos" successfully extended
[root@localhost ~]# vgdisplay
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 2
Act PV 2
VG Size 58.99 GiB
PE Size 4.00 MiB
Total PE 15102
Alloc PE / Size 12542 / 48.99 GiB
Free PE / Size 2560 / 10.00 GiB
VG UUID 682d9M-yRsn-60BJ-cY7f-nAVI-WA24-KmnhD1
5. Logical volume expansion
[root@localhost ~]# lvdisplay
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID DmOkUA-Fq7K-eTwy-I338-jwiv-Qt7g-s9kdFW
LV Write Access read/write
LV Creation host, time localhost, 2020-01-08 11:35:41 -0500
LV Status available
# open 2
LV Size 2.00 GiB
Current LE 512
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/centos/root
LV Name root
VG Name centos
LV UUID KZEsXa-9uNA-Nei7-gnu3-1tmU-BDwq-LSFo7Q
LV Write Access read/write
LV Creation host, time localhost, 2020-01-08 11:35:42 -0500
LV Status available
# open 1
LV Size 46.99 GiB
Current LE 12030
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
[root@localhost ~]# lvextend -l +100%free /dev/mapper/centos-root
Size of logical volume centos/root changed from 46.99 GiB (12030 extents) to 56.99 GiB (14590 extents).
Logical volume centos/root successfully resized.
6. Dynamically format and expand the disk
[root@localhost ~]# lvextend -l +100%free /dev/mapper/centos-root
Size of logical volume centos/root changed from 46.99 GiB (12030 extents) to 56.99 GiB (14590 extents).
Logical volume centos/root successfully resized.
[root@localhost ~]# man lvextend
[root@localhost ~]# xfs_growfs /dev/mapper/centos-root
meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=3079680 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=12318720, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=6015, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 12318720 to 14940160
7. Verification (success)
[root@localhost ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 57G 2.1G 55G 4% /
devtmpfs devtmpfs 903M 0 903M 0% /dev
tmpfs tmpfs 915M 0 915M 0% /dev/shm
tmpfs tmpfs 915M 9.3M 906M 2% /run
tmpfs tmpfs 915M 0 915M 0% /sys/fs/cgroup
/dev/sda1 xfs 1014M 146M 869M 15% /boot
tmpfs tmpfs 183M 0 183M 0% /run/user/0
Three, summary
Before adjusting the disk size, it is strongly recommended to back up important data, especially database data.
df -hT
# 列出磁盘
fdisk -l
# 操作磁盘/dev/sda
fdisk /dev/sda
Command (m for help): p
Command (m for help): n
Command (m for help): t
Command (m for help): w
# 同步磁盘状态（若同步失败，重启虚拟机）
partprobe
reboot
# 查看物理卷
pvdisplay
# 创建物理卷
pvcreate /dev/sda3
# 查看卷组（1个或多个）
vgdisplay
# 扩展卷组centos
vgextend centos /dev/sda3
# 查看lvm卷
lvdisplay
# 扩展lvm卷/dev/mapper/centos-root
lvextend -l +100%free /dev/mapper/centos-root
# 动态扩容
xfs_growfs /dev/mapper/centos-root
# 确认
df -hT
If the host computer adds a new disk; Step 2 (create partition) can be changed to operate disk /dev/sdb!
```shell
[root@localhost ~]# fdisk /dev/sdb
Reprinted:
LVM expansion volume