LVM逻辑卷扩容缩容

Posted 2020-11-18 xiaoliangxianshen

LVM就是动态卷管理，可以将多个硬盘和硬盘分区做成一个逻辑卷，并把这个逻辑卷作为一个整体来统一管理，动态对分区进行扩缩空间大小，安全快捷方便管理。 后期出现问题恢复数据也比较麻烦。

概念：

①PE(Physical Extend) 物理拓展

②PV(Physical Volume) 物理卷

③VG(Volume Group) 卷组

④LV(Logical Volume) 逻辑卷

 

特点：

LVM最大的特点就是可以对磁盘进行动态管理。因为逻辑卷的大小是可以动态调整的，而且不会丢失现有的数据。我们如果新增加了硬盘，其也不会改变现有上层的逻辑卷。作为一个动态磁盘管理机制，逻辑卷技术大大提高了磁盘管理的灵活性！

原理：

(1)物理磁盘被格式化为PV，空间被划分为一个个的PE

(2)不同的PV加入到同一个VG中，不同PV的PE全部进入到了VG的PE池内

(3)LV基于PE创建，大小为PE的整数倍，组成LV的PE可能来自不同的物理磁盘

(4)LV现在就直接可以格式化后挂载使用了

(5)LV的扩充缩减实际上就是增加或减少组成该LV的PE数量，其过程不会丢失原始数据

工作流程：

磁盘分区-->创建物理卷-->划分为卷组-->划分成逻辑卷-->格式化、挂载-->扩容。

实例：

首先从磁盘/sdb划分三个分区，每个磁盘为1G，把类型改变为8e，也就是lvm类型。只要改变分区类型，才能去做物理卷。

1、安装lvm软件包

2、fdisk /dev/sdb

3、n 创建三个新分区，分别1G

4、t 改变分区类型为8e

[[email protected] ~]# yum install -y lvm2-2.02.177-4.el7.x86_64

[[email protected] ~]# 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.

 

Device does not contain a recognized partition table

Building a new DOS disklabel with disk identifier 0x342d0935.

 

Command (m for help): n

Partition type:

   p   primary (0 primary, 0 extended, 4 free)

   e   extended

Select (default p):

Using default response p

Partition number (1-4, default 1):

First sector (2048-20971519, default 2048):

Using default value 2048

Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): +1G

Partition 1 of type Linux and of size 1 GiB is set

 

Command (m for help): t

Selected partition 1

Hex code (type L to list all codes): 8e

Changed type of partition ‘Linux‘ to ‘Linux LVM‘

 

Command (m for help): n

Partition type:

   p   primary (1 primary, 0 extended, 3 free)

   e   extended

Select (default p): p

Partition number (2-4, default 2): 2

First sector (2099200-20971519, default 2099200):

Using default value 2099200

Last sector, +sectors or +size{K,M,G} (2099200-20971519, default 20971519): +1G

Partition 2 of type Linux and of size 1 GiB is set

 

Command (m for help): t

Partition number (1,2, default 2):

Hex code (type L to list all codes): 8e

Changed type of partition ‘Linux‘ to ‘Linux LVM‘

 

Command (m for help): n

Partition type:

   p   primary (2 primary, 0 extended, 2 free)

   e   extended

Select (default p): p

Partition number (3,4, default 3): 3

First sector (4196352-20971519, default 4196352):

Using default value 4196352

Last sector, +sectors or +size{K,M,G} (4196352-20971519, default 20971519): +1G

Partition 3 of type Linux and of size 1 GiB is set

 

Command (m for help): t

Partition number (1-3, default 3): 3

Hex code (type L to list all codes): 8e

Changed type of partition ‘Linux‘ to ‘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.

 

[[email protected] ~]# fdisk -l /dev/sdb

 

Disk /dev/sdb: 10.7 GB, 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

Disk label type: dos

Disk identifier: 0x05c1aa40

 

   Device Boot      Start         End      Blocks   Id  System

/dev/sdb1            2048     2099199     1048576   8e  Linux LVM

/dev/sdb2         2099200     4196351     1048576   8e  Linux LVM

/dev/sdb3         4196352     6293503     1048576   8e  Linux LVM

一般情况在创建完分区后系统会自动生成相应的分区文件“/dev/sdb”，但是当系统未自动生成时无法完成物理卷创建任务，需要执行命令 “partprobe” 生成相应文件再执行pvcreate命令。

创建PV物理卷，使用pvs&pvdisplay查看物理卷的信息。

[[email protected] ~]# partprobe /dev/sdb

[[email protected] ~]# pvcreate /dev/sdb1   #创建物理卷

WARNING: ext4 signature detected on /dev/sdb1 at offset 1080. Wipe it? [y/n]: y

  Wiping ext4 signature on /dev/sdb1.

  Physical volume "/dev/sdb1" successfully created.

[[email protected] ~]# pvcreate /dev/sdb2

  Physical volume "/dev/sdb2" successfully created.

[[email protected] ~]# pvcreate /dev/sdb3

  Physical volume "/dev/sdb3" successfully created.

[[email protected] ~]# pvs    #查看创建的物理卷详细信息

  PV         VG Fmt  Attr PSize PFree

  /dev/sdb1     lvm2 ---  1.00g 1.00g

  /dev/sdb2     lvm2 ---  1.00g 1.00g

  /dev/sdb3     lvm2 ---  1.00g 1.00g

创建VG卷组，使用vgs&vgdisplay查看卷组的详细信息。

[[email protected] ~]# vgcreate vg1 /dev/sdb1 /dev/sdb2 #vg1为卷组名,把sdb1,sdb2加入

  Volume group "vg1" successfully created

[[email protected] ~]# vgs  #查看创建的卷组详细信息

  VG  #PV #LV #SN Attr   VSize VFree

  vg1   2   0   0 wz--n- 1.99g 1.99g

创建LV逻辑卷，使用lvs&display查看逻辑卷的详细信息

选项：

-L：指定逻辑卷的大小，单位为“kKmMgGtT”字节

-n：指定逻辑卷的名称。

[[email protected] ~]# lvcreate -L 100M -n lv1 vg1 #-L指定创建100M的空间，-n指定逻辑卷的名字为lv1，从vg1卷组里面划分100M的空间。

  Logical volume "lv1" created.

[[email protected] ~]# lvs

  LV   VG  Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert

  lv1  vg1 -wi-a----- 100.00m              

格式化为ext4文件系统。

[[email protected] ~]# mkfs.ext4 /dev/vg1/lv1

mke2fs 1.42.9 (28-Dec-2013)

Filesystem label=

OS type: Linux

Block size=1024 (log=0)

Fragment size=1024 (log=0)

Stride=0 blocks, Stripe width=0 blocks

25688 inodes, 102400 blocks

5120 blocks (5.00%) reserved for the super user

First data block=1

Maximum filesystem blocks=33685504

13 block groups

8192 blocks per group, 8192 fragments per group

1976 inodes per group

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

 格式化后使用mount挂载 

[[email protected] ~]# mount /dev/vg1/lv1 /mnt/

[[email protected] ~]# df -hT

Filesystem          Type      Size  Used Avail Use% Mounted on

/dev/sda2           xfs        44G  1.8G   43G   5% /

devtmpfs            devtmpfs  1.9G     0  1.9G   0% /dev

tmpfs               tmpfs     1.9G     0  1.9G   0% /dev/shm

tmpfs               tmpfs     1.9G  8.5M  1.9G   1% /run

tmpfs               tmpfs     1.9G     0  1.9G   0% /sys/fs/cgroup

/dev/sda5           xfs      1014M   33M  982M   4% /home

/dev/sda1           xfs      1014M  135M  880M  14% /boot

tmpfs               tmpfs     378M     0  378M   0% /run/user/0

/dev/mapper/vg1-lv1 ext4       93M  1.6M   85M   2% /mnt

[[email protected] ~]# ls -l /dev/vg1/lv1

lrwxrwxrwx. 1 root root 7 Jun 15 20:01 /dev/vg1/lv1 -> ../dm-0

[[email protected] ~]# ls -l /dev/mapper/vg1-lv1

lrwxrwxrwx. 1 root root 7 Jun 15 20:01 /dev/mapper/vg1-lv1 -> ../dm-0

扩容逻辑卷

工作流程：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）

lvresize命令（=logical volume resize）用于调整LVM逻辑卷的空间大小，可以增大空间和缩小空间。使用lvresize命令调整逻辑卷空间大小和缩小空间时需要谨慎，因为它有可能导致数据丢失。

[[email protected] ~]# cd /mnt/

[[email protected] mnt]# mkdir 1212        #往里面写些数据

[[email protected] mnt]# touch 1.txt

[[email protected] mnt]# echo "11111111111" > 1.txt

[[email protected] ~]# umount /mnt/

[[email protected] ~]# lvresize -L 200M /dev/vg1/lv1  #原本是100M，现在扩容成200M

  Size of logical volume vg1/lv1 changed from 100.00 MiB (25 extents) to 200.00 MiB (50 extents).

  Logical volume vg1/lv1 successfully resized.

[[email protected] ~]# lvs

  LV   VG  Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert

  lv1  vg1 -wi-a----- 200.00m    

e2fsck 命令，检查磁盘是否有错误，只适用ext4文件系统

[[email protected] ~]# e2fsck -f /dev/vg1/lv1   

e2fsck 1.42.9 (28-Dec-2013)

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/vg1/lv1: 13/25688 files (7.7% non-contiguous), 8899/102400 blocks

resize2fs命令，更新逻辑卷信息只适用ext4文件系统

[[email protected] ~]# resize2fs /dev/vg1/lv1

resize2fs 1.42.9 (28-Dec-2013)

Resizing the filesystem on /dev/vg1/lv1 to 204800 (1k) blocks.

The filesystem on /dev/vg1/lv1 is now 204800 blocks long.

[[email protected] ~]# lvs

  LV   VG  Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert

  lv1  vg1 -wi-a----- 200.00m     

[[email protected] ~]# !mount

mount /dev/vg1/lv1 /mnt/

[[email protected] ~]# df -hT

Filesystem          Type      Size  Used Avail Use% Mounted on

/dev/sda2           xfs        44G  1.8G   43G   5% /

devtmpfs            devtmpfs  1.9G     0  1.9G   0% /dev

tmpfs               tmpfs     1.9G     0  1.9G   0% /dev/shm

tmpfs               tmpfs     1.9G  8.5M  1.9G   1% /run

tmpfs               tmpfs     1.9G     0  1.9G   0% /sys/fs/cgroup

/dev/sda5           xfs      1014M   33M  982M   4% /home

/dev/sda1           xfs      1014M  135M  880M  14% /boot

tmpfs               tmpfs     378M     0  378M   0% /run/user/0

/dev/mapper/vg1-lv1 ext4      190M  1.6M  175M   1% /mnt

[[email protected] ~]# ls /mnt/   #扩容不会丢失数据

1212  1.txt  lost+found

缩容逻辑卷(xfs不支持)

工作流程：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）

注：合理缩容也不会使系统内文件丢失

[[email protected] ~]# umount /mnt/

[[email protected] ~]# e2fsck -f /dev/vg1/lv1

e2fsck 1.42.9 (28-Dec-2013)

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/vg1/lv1: 13/49400 files (7.7% non-contiguous), 11887/204800 blocks

[[email protected] ~]# resize2fs /dev/vg1/lv1 100M

resize2fs 1.42.9 (28-Dec-2013)

Resizing the filesystem on /dev/vg1/lv1 to 102400 (1k) blocks.

The filesystem on /dev/vg1/lv1 is now 102400 blocks long.

 

[[email protected] ~]# lvresize -L 100M  /dev/vg1/lv1  

  WARNING: Reducing active logical volume to 100.00 MiB.

  THIS MAY DESTROY YOUR DATA (filesystem etc.)

Do you really want to reduce vg1/lv1? [y/n]: y

  Size of logical volume vg1/lv1 changed from 200.00 MiB (50 extents) to 100.00 MiB (25 extents).

  Logical volume vg1/lv1 successfully resized.

[[email protected] ~]# !mount

mount /dev/vg1/lv1 /mnt/

[[email protected] ~]# lvs

  LV   VG  Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert

  lv1  vg1 -wi-ao---- 100.00m                                                    

[[email protected] ~]# df -hT

Filesystem          Type      Size  Used Avail Use% Mounted on

/dev/sda2           xfs        44G  1.8G   43G   5% /

devtmpfs            devtmpfs  1.9G     0  1.9G   0% /dev

tmpfs               tmpfs     1.9G     0  1.9G   0% /dev/shm

tmpfs               tmpfs     1.9G  8.5M  1.9G   1% /run

tmpfs               tmpfs     1.9G     0  1.9G   0% /sys/fs/cgroup

/dev/sda5           xfs      1014M   33M  982M   4% /home

/dev/sda1           xfs      1014M  135M  880M  14% /boot

tmpfs               tmpfs     378M     0  378M   0% /run/user/0

/dev/mapper/vg1-lv1 ext4       93M  1.6M   85M   2% /mnt

[[email protected] ~]# ls /mnt/

1212  1.txt  lost+found

格式化为XFS文件系统

[[email protected] ~]# umount /mnt/

[[email protected] ~]# mkfs.xfs -f /dev/vg1/lv1

meta-data=/dev/vg1/lv1           isize=512    agcount=4, agsize=6400 blks

         =                       sectsz=512   attr=2, projid32bit=1

         =                       crc=1        finobt=0, sparse=0

data     =                       bsize=4096   blocks=25600, imaxpct=25

         =                       sunit=0      swidth=0 blks

naming   =version 2              bsize=4096   ascii-ci=0 ftype=1

log      =internal log           bsize=4096   blocks=855, version=2

         =                       sectsz=512   sunit=0 blks, lazy-count=1

realtime =none                   extsz=4096   blocks=0, rtextents=0

对xfs文件系统的分区进行扩容

工作流程更改逻辑卷信息（lvresize）-->更新逻辑卷信息（xfs_growfs）

1.更改逻辑卷信息

[[email protected] ~]# lvresize -L 300M /dev/vg1/lv1

  Size of logical volume vg1/lv1 changed from 100.00 MiB (25 extents) to 300.00 MiB (75 extents).

  Logical volume vg1/lv1 successfully resized.

[[email protected] ~]# lvs

  LV   VG  Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert

  lv1  vg1 -wi-ao---- 300.00m     

[[email protected] ~]# df -hT

Filesystem          Type      Size  Used Avail Use% Mounted on

/dev/sda2           xfs        44G  1.8G   43G   5% /

devtmpfs            devtmpfs  1.9G     0  1.9G   0% /dev

tmpfs               tmpfs     1.9G     0  1.9G   0% /dev/shm

tmpfs               tmpfs     1.9G  8.5M  1.9G   1% /run

tmpfs               tmpfs     1.9G     0  1.9G   0% /sys/fs/cgroup

/dev/sda5           xfs      1014M   33M  982M   4% /home

/dev/sda1           xfs      1014M  135M  880M  14% /boot

tmpfs               tmpfs     378M     0  378M   0% /run/user/0

/dev/mapper/vg1-lv1 xfs        97M  5.2M   92M   6% /mnt

2.更新逻辑卷信息

注：执行xfs格式更新逻辑卷的命令，前提是分区必须要在挂载的状态下执行

[[email protected] ~]# !mount

mount /dev/vg1/lv1 /mnt/

[[email protected] ~]# xfs_growfs /dev/vg1/lv1         

meta-data=/dev/mapper/vg1-lv1    isize=512    agcount=4, agsize=6400 blks

         =                       sectsz=512   attr=2, projid32bit=1

         =                       crc=1        finobt=0 spinodes=0

data     =                       bsize=4096   blocks=25600, imaxpct=25

         =                       sunit=0      swidth=0 blks

naming   =version 2              bsize=4096   ascii-ci=0 ftype=1

log      =internal               bsize=4096   blocks=855, version=2

         =                       sectsz=512   sunit=0 blks, lazy-count=1

realtime =none                   extsz=4096   blocks=0, rtextents=0

data blocks changed from 25600 to 76800

[[email protected] ~]# df -hT

Filesystem          Type      Size  Used Avail Use% Mounted on

/dev/sda2           xfs        44G  1.8G   43G   5% /

devtmpfs            devtmpfs  1.9G     0  1.9G   0% /dev

tmpfs               tmpfs     1.9G     0  1.9G   0% /dev/shm

tmpfs               tmpfs     1.9G  8.5M  1.9G   1% /run

tmpfs               tmpfs     1.9G     0  1.9G   0% /sys/fs/cgroup

/dev/sda5           xfs      1014M   33M  982M   4% /home

/dev/sda1           xfs      1014M  135M  880M  14% /boot

tmpfs               tmpfs     378M     0  378M   0% /run/user/0

/dev/mapper/vg1-lv1 xfs       297M  5.5M  292M   2% /mnt

 

vgextend命令扩容卷组(将sdb3加入到vg1)

使用vgs或者使用vgdisplay查看卷组的详细信息。

[[email protected] ~]# pvcreate /dev/sdb3   #扩展卷组时，先创建物理卷。

[[email protected] ~]# vgextend vg1 /dev/sdb3

  Volume group "vg1" successfully extended

[[email protected] ~]# vgs

  VG  #PV #LV #SN Attr   VSize  VFree

  vg1   3   1   0 wz--n- <2.99g <2.70g