LVM-详解
目录
LVM 定义
逻辑卷管理器（Logical Volume Manager，LVM）。
LVM允许用户对硬盘资源进行动态调整。
LVM是Linux系统用于对硬盘分区进行管理的一种机制，其是在硬盘分区和文件系统之间添加了一个逻辑层，它提供了一个抽象的卷组，可以把多块硬盘进行卷组合并。
- 物理卷处于LVM中的最底层，可以将其理解为物理硬盘、硬盘分区或者RAID磁盘阵列。
- 卷组建立在物理卷之上，一个卷组能够包含多个物理卷，而且在卷组创建之后也可以继续向其中添加新的物理卷。
- 逻辑卷是用卷组中空闲的资源建立的，并且逻辑卷在建立后可以动态地扩展或缩小空间。这就是LVM的核心理念。
常用命令合集
| 功能/命令 | 物理卷管理 | 卷组管理 | 逻辑卷管理 |
|---|---|---|---|
| 扫描 | pvscan | vgscan | lvscan |
| 建立 | pvcreate | vgcreate | lvcreate |
| 显示 | pvdisplay | vgdisplay | lvdispaly |
| 删除 | pvremove | vgremove | lvremove |
| 扩展 | 添加磁盘 | vgextend | lvextend |
| 缩小 | 删除磁盘 | vgreduce | lvreduce |
命令详解
vgcreate
示例：vgcreate [vg.name] [/dev/sd*][可添加多个] [参数]
| 参数 | 说明 |
|---|---|
| -L | 指定块大小 |
LVM实验
实验目标
创建
VgTest卷组。
创建LvTest逻辑卷。
使用/dev/sdb和/dev/sdc两个物理卷【大小分别为10G】。
挂载到/mnt/LvTest/目录下，并写入配置文件。
使用/dev/sdd1为LVTest扩容【/dev/sdc1大小为3G】。
逆向缩容，使/dev/sd{a,b,c}三块磁盘置空。
创建LV
创建物理卷和卷组
- 通过
lsblk查看当前磁盘信息
[root@Servere ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 40G 0 disk
├─sda1 8:1 0 1G 0 part /boot
└─sda2 8:2 0 39G 0 part
├─cs-root 253:0 0 36.9G 0 lvm /
└─cs-swap 253:1 0 2.1G 0 lvm [SWAP]
sdb 8:16 0 10G 0 disk
sdc 8:32 0 10G 0 disk
sdd 8:48 0 10G 0 disk
使用
pvcreate&vgcreate分别创建物理卷和卷组
[root@Servere ~]# pvcreate /dev/sdb /dev/sdc
Physical volume "/dev/sdb" successfully created.
Physical volume "/dev/sdc" successfully created.
[root@Servere ~]# vgcreate VgTest /dev/sdb /dev/sdc
Volume group "VgTest" successfully created
使用
pvdisplay&vgdisplay查看创建好的物理卷和卷组
[root@Servere ~]# pvdisplay
--- Physical volume ---
PV Name /dev/sdb
VG Name VgTest
PV Size 10.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 2559
Free PE 2559
Allocated PE 0
PV UUID j2RqkR-l7uZ-E4zZ-306C-lVXK-L38M-LEge20
--- Physical volume ---
PV Name /dev/sdc
VG Name VgTest
PV Size 10.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 2559
Free PE 2559
Allocated PE 0
PV UUID Wjps5a-fp9w-cHcr-0xTm-2hTw-UsHR-6sgnpE
[root@Servere ~]# vgdisplay
--- Volume group ---
VG Name VgTest
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 19.99 GiB
PE Size 4.00 MiB
Total PE 5118
Alloc PE / Size 0 / 0
Free PE / Size 5118 / 19.99 GiB
VG UUID 2SYOGi-73dK-wisb-X6sk-kDxg-hSOv-m8rGsn
使用
pvscan&vgscan&lvscan扫描创建好的物理卷和卷组
[root@Servere ~]# pvscan
PV /dev/sdb VG VgTest lvm2 [<10.00 GiB / <10.00 GiB free]
PV /dev/sdc VG VgTest lvm2 [<10.00 GiB / <10.00 GiB free]
PV /dev/sda2 VG cs lvm2 [<39.00 GiB / 0 free]
Total: 3 [<58.99 GiB] / in use: 3 [<58.99 GiB] / in no VG: 0 [0]
[root@Servere ~]# vgscan
Found volume group "VgTest" using metadata type lvm2
Found volume group "cs" using metadata type lvm2
[root@Servere ~]# lvscan
ACTIVE '/dev/cs/swap' [2.08 GiB] inherit
ACTIVE '/dev/cs/root' [36.91 GiB] inherit
创建逻辑卷
使用
lvcreate创建逻辑卷
[root@Servere ~]# lvcreate -l 100%FREE -n LvTest /dev/VgTest
Logical volume "LvTest" created.
使用
lvscan&lvdisplay扫描和查看创建好的逻辑卷信息
[root@Servere ~]# lvscan
ACTIVE '/dev/VgTest/LvTest' [19.99 GiB] inherit
ACTIVE '/dev/cs/swap' [2.08 GiB] inherit
ACTIVE '/dev/cs/root' [36.91 GiB] inherit
[root@Servere ~]# lvdisplay
--- Logical volume ---
LV Path /dev/VgTest/LvTest
LV Name LvTest
VG Name VgTest
LV UUID iFsJX5-xJEm-g8S3-43KJ-etcs-F4VR-5hYlkS
LV Write Access read/write
LV Creation host, time Servere.lab.example.com, 2023-05-22 09:51:43 +0800
LV Status available
# open 0
LV Size 19.99 GiB
Current LE 5118
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
挂载
[root@Servere ~]# mkdir /mnt/LvTest
[root@Servere ~]# mount /dev/VgTest/LvTest /mnt/LvTest/
[root@Servere ~]# echo "/dev/mapper/VgTest-LvTest /mnt/LvTest/ ext4 defaults 0 0" >> /etc/fstab
[root@Servere ~]# mount -a
[root@Servere ~]# df -Th
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/cs-root xfs 37G 2.1G 35G 6% /
/dev/mapper/VgTest-LvTest ext4 20G 45M 19G 1% /mnt/LvTest
扩容LV
注意事项：
- umount卸载挂载点
- 重新设置逻辑卷大小（lvresize）
- 检测磁盘错误（e2fsck -f）
- 更新逻辑卷信息（resize2fs）
分配逻辑卷组
物理卷 > 卷组 > 逻辑卷
[root@Servere ~]# fdisk /dev/sdd
Welcome to fdisk (util-linux 2.32.1).
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.
Created a new DOS disklabel with disk identifier 0xa9dbbfa0.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p):
Using default response p.
Partition number (1-4, default 1):
First sector (2048-20971519, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-20971519, default 20971519): +3G # 为sdd1分配3G大小的容量
Created a new partition 1 of type 'Linux' and of size 3 GiB.
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): 8e # 使用`8e`格式的
Changed type of partition 'Linux' to 'Linux LVM'.
Command (m for help): p
Disk /dev/sdd: 10 GiB, 10737418240 bytes, 20971520 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
Disklabel type: dos
Disk identifier: 0xa9dbbfa0
Device Boot Start End Sectors Size Id Type
/dev/sdd1 2048 6293503 6291456 3G 8e Linux LVM
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
扩容卷组
- vgextend 【vg_name】 【device】
[root@Servere ~]# df -Th
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/cs-root xfs 37G 2.1G 35G 6% /
/dev/mapper/VgTest-LvTest ext4 20G 45M 19G 1% /mnt/LvTest
[root@Servere ~]# vgextend VgTest /dev/sdd1
Physical volume "/dev/sdd1" successfully created.
Volume group "VgTest" successfully extended
扩容逻辑卷
- lvextend -l +100%FREE 【/dev/mapper/...】
[root@Servere ~]# lvextend /dev/mapper/VgTest-LvTest /dev/sdd1 -L +2.99G
Rounding size to boundary between physical extents: 2.99 GiB.
Size of logical volume VgTest/LvTest changed from 19.99 GiB (5118 extents) to 22.98 GiB (5884 extents).
Logical volume VgTest/LvTest successfully resized.
检测磁盘错误
- 需要解除挂载目录
- 仅适用于
ext4文件系统
[root@Servere ~]# umount /mnt/LvTest
[root@Servere ~]# e2fsck -f /dev/mapper/VgTest-LvTest
e2fsck 1.45.6 (20-Mar-2020)
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/VgTest-LvTest: 11/1966080 files (0.0% non-contiguous), 167442/7858176 blocks
扩容文件系统
方法一：
- resize2fs -f 【/dev/mapper/...】
[root@Servere ~]# resize2fs /dev/mapper/VgTest-LvTest -f
resize2fs 1.45.6 (20-Mar-2020)
Filesystem at /dev/mapper/VgTest-LvTest is mounted on /mnt/LvTest; on-line resizing required
old_desc_blocks = 3, new_desc_blocks = 3
The filesystem on /dev/mapper/VgTest-LvTest is now 6025216 (4k) blocks long.
方法二：
- 将
/dev/sdd剩余空间添加到/dev/mapper/VgTest-LvTest内。 - 直接使用
lvextend中-r参数。
[root@Servere ~]# lvextend -L +6.99G /dev/mapper/VgTest-LvTest /dev/sdd2 -r
Rounding size to boundary between physical extents: 6.99 GiB.
Size of logical volume VgTest/LvTest changed from 22.98 GiB (5884 extents) to <29.98 GiB (7674 extents).
Logical volume VgTest/LvTest successfully resized.
resize2fs 1.45.6 (20-Mar-2020)
Filesystem at /dev/mapper/VgTest-LvTest is mounted on /mnt/LvTest; on-line resizing required
old_desc_blocks = 3, new_desc_blocks = 4
The filesystem on /dev/mapper/VgTest-LvTest is now 7858176 (4k) blocks long.
缩容
注意事项：
- 卸载（umount）
- 检测（e2fsck -f）
- 更新逻辑卷信息大小（resize2fs）
- 重置逻辑卷大小（lvresize）
卸载
[root@Servere ~]# umount /mnt/LvTest
检测磁盘错误
[root@Servere ~]# e2fsck -f /dev/mapper/VgTest-LvTest
e2fsck 1.45.6 (20-Mar-2020)
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/VgTest-LvTest: 11/1966080 files (0.0% non-contiguous), 167442/7858176 blocks
更新逻辑卷信息
[root@Servere ~]# resize2fs /dev/mapper/VgTest-LvTest
resize2fs 1.45.6 (20-Mar-2020)
The filesystem is already 7858176 (4k) blocks long. Nothing to do!
重置逻辑卷大小
逻辑卷 > 卷组 > 物理卷
[root@Servere ~]# lvremove /dev/mapper/VgTest-LvTest
Do you really want to remove active logical volume VgTest/LvTest? [y/n]: y
Logical volume "LvTest" successfully removed.
重置卷组
[root@Servere ~]# vgremove VgTest
Volume group "VgTest" successfully removed
重置物理卷
- 通过
pvremove删除创建的物理卷
[root@Servere ~]# pvremove /dev/sdd{1,2}
Labels on physical volume "/dev/sdd1" successfully wiped.
Labels on physical volume "/dev/sdd2" successfully wiped.
- 通过
fdisk删除创建的物理卷
[root@Servere ~]# fdisk /dev/sdd
Welcome to fdisk (util-linux 2.32.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): d
Partition number (1,2, default 2):
Partition 2 has been deleted.
Command (m for help): d
Selected partition 1
Partition 1 has been deleted.
Command (m for help): p
Disk /dev/sdd: 10 GiB, 10737418240 bytes, 20971520 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
Disklabel type: dos
Disk identifier: 0xa9dbbfa0
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
