LVM相关介绍

LVM概念

Logical Volume Manager 逻辑卷管理

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通过将底层物理硬盘抽象封装起来，以逻辑卷的形式表现给上层系统，逻辑卷的大小可以动态调整，而且不会丢失现有数据。新加入的硬盘也不会改变现有上层的逻辑卷。
作为一种多台磁盘管理机制，逻辑卷技术大大提高了磁盘管理的灵活性。

LVM的4个基本概念

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① PE　　(Physical Extend)　　物理拓展
② PV　　(Physical Volume)　　物理卷
③ VG　　(Volume Group)　　卷组
④ LV　　(Logical Volume)　　逻辑卷

PE逻辑卷空间管理的最基本单位。1个PE默认是4M大小
VG的作用是用来装PV的–空间池

创建LVM

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➜  ~ fdisk -l
Disk /dev/sda: 300 GiB, 322122547200 bytes, 629145600 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: 0xc1fc20ae
Device     Boot     Start       End   Sectors  Size Id Type
/dev/sda1  *         2048 612370431 612368384  292G 83 Linux
/dev/sda2       612372478 629143551  16771074    8G  5 Extended
/dev/sda5       612372480 629143551  16771072    8G 82 Linux swap / Solaris
Disk /dev/sdb: 50 GiB, 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
  1. 将物理磁盘设备初始化为物理卷
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    ➜  ~ pvcreate /dev/sdb
      Physical volume "/dev/sdb" successfully created

查看物理卷信息

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➜  ~ pvs
  PV         VG   Fmt  Attr PSize  PFree
  /dev/sdb        lvm2 ---  50.00g 50.00g

  1. 创建卷组，并将PV加入卷组中
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    >名字为lvmtest， 可任意
    ➜  ~ vgcreate lvmtest /dev/sdb
      Volume group "lvmtest" successfully created
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➜  ~ vgs
  VG      #PV #LV #SN Attr   VSize  VFree
  lvmtest   1   0   0 wz--n- 50.00g 50.00g
>查看卷组信息
➜  ~ vgdisplay
  --- Volume group ---
  VG Name               lvmtest
  System ID             
  Format                lvm2
  Metadata Areas        1
  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                1
  Act PV                1
  VG Size               50.00 GiB
  PE Size               4.00 MiB
  Total PE              12799
  Alloc PE / Size       0 / 0   
  Free  PE / Size       12799 / 50.00 GiB
  VG UUID               cxMG1m-pMAE-Suk5-bM69-1sB3-W7YB-WXmmGh
  1. 基于卷组创建逻辑卷

    这里我从lvmtest拿了20G空间来创建了一个名为lv1的逻辑卷

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    ➜  ~ lvcreate -n lv1 -L 20G lvmtest
      Logical volume "lv1" created

查看逻辑卷信息

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➜  ~ lvs
  LV   VG      Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv1  lvmtest -wi-a----- 20.00g                                                    
➜  ~ lvdisplay
  --- Logical volume ---
  LV Path                /dev/lvmtest/lv1
  LV Name                lv1
  VG Name                lvmtest
  LV UUID                Q4UIbv-yWhL-Bl5A-ywTN-1HJo-TE5r-TKBPfQ
  LV Write Access        read/write
  LV Creation host, time kali, 2016-08-03 08:44:31 +0800
  LV Status              available
  # open                 0
  LV Size                20.00 GiB
  Current LE             5120
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           254:0

  1. 为创建好的逻辑卷创建文件系统

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    ➜  ~ mkfs.ext4 /dev/lvmtest/lv1
    mke2fs 1.42.12 (29-Aug-2014)
    Creating filesystem with 5242880 4k blocks and 1310720 inodes
    Filesystem UUID: 5130e6e1-8293-4fcb-b580-5091f3840f99
    Superblock backups stored on blocks:
    	32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
    	4096000
    Allocating group tables: done                            
    Writing inode tables: done                            
    Creating journal (32768 blocks): done
    Writing superblocks and filesystem accounting information: done

  2. 将格式化好的逻辑卷挂载使用

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    ➜  ~ mount /dev/lvmtest/lv1 /mnt/

查看

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➜  /mnt mount | tail -n 1
/dev/mapper/lvmtest-lv1 on /mnt type ext4 (rw,relatime,data=ordered)

删除LVM

先把相应的东西umount掉

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➜  ~ umount /mnt

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➜  ~ mount | tail -n 1
/dev/sr0 on /media/cdrom0 type iso9660 (ro,nosuid,nodev,noexec,relatime,user)

  1. 删除LV

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    ➜  ~ lvremove /dev/lvmtest/lv1
    Do you really want to remove active logical volume lv1? [y/n]: y
      Logical volume "lv1" successfully removed

  2. 删除VG

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    ➜  ~ vgremove lvmtest
      Volume group "lvmtest" successfully removed

  3. 删除物理卷

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    ➜  ~ pvremove /dev/sdb
      Labels on physical volume "/dev/sdb" successfully wiped

扩充逻辑卷容量

逻辑卷的拉伸操作可以在线执行，不需要卸载逻辑卷

  1. 保证VG中有足够的空闲空间
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➜  ~ vgs
  VG   #PV #LV #SN Attr   VSize  VFree
  vg     1   1   0 wz--n- 50.00g 30.00g

  1. 扩充逻辑卷

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    ➜  ~ lvextend  -L +1G /dev/vg/lv
      Size of logical volume vg/lv changed from 20.00 GiB (5120 extents) to 21.00 GiB (5376 extents).
      Logical volume lv successfully resized

  2. 查看扩充后LV大小

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    ➜  ~ lvdisplay
      --- Logical volume ---
      LV Path                /dev/vg/lv
      LV Name                lv
      VG Name                vg
      LV UUID                5q9mCJ-7Y3f-dEo7-xlDz-lJAW-Oczm-RuCeIE
      LV Write Access        read/write
      LV Creation host, time kali, 2016-08-03 09:51:18 +0800
      LV Status              available
      # open                 0
      LV Size                21.00 GiB
      Current LE             5376
      Segments               1
      Allocation             inherit
      Read ahead sectors     auto
      - currently set to     256
      Block device           254:0

  3. 更新文件系统

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    ➜  ~ resize2fs /dev/vg/lv
    resize2fs 1.42.12 (29-Aug-2014)
    Filesystem at /dev/vg/lv is mounted on /mnt; on-line resizing required
    old_desc_blocks = 2, new_desc_blocks = 2
    The filesystem on /dev/vg/lv is now 5505024 (4k) blocks long.

  4. 查看更新后文件系统

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    ➜  ~ df -h
    Filesystem         Size  Used Avail Use% Mounted on
    udev                10M     0   10M   0% /dev
    tmpfs              792M  9.1M  783M   2% /run
    /dev/sda1          288G   16G  257G   6% /
    tmpfs              2.0G  208K  2.0G   1% /dev/shm
    tmpfs              5.0M     0  5.0M   0% /run/lock
    tmpfs              2.0G     0  2.0G   0% /sys/fs/cgroup
    tmpfs              396M  8.0K  396M   1% /run/user/132
    tmpfs              396M   12K  396M   1% /run/user/0
    /dev/sr0           3.1G  3.1G     0 100% /media/cdrom0
    /dev/mapper/vg-lv   21G   44M   20G   1% /mnt

扩充卷组容量

  1. 将要添加到VG的硬盘格式化为PV

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    ➜  ~ pvcreate /dev/sdc
      Physical volume "/dev/sdc" successfully created

  2. 将新的PV添加到指定卷组中

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    ➜  ~ vgextend vg /dev/sdc
      Volume group "vg" successfully extended

  3. 查看扩充后VG大小

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    ➜  ~ vgs
      VG   #PV #LV #SN Attr   VSize  VFree
      vg     2   1   0 wz--n- 69.99g 48.99g

缩小逻辑卷容量

逻辑卷的缩小操作必须离线执行，要卸载逻辑卷

  1. 卸载一键挂载的逻辑卷

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    ➜  ~ umount /dev/mapper/vg-lv

  2. 缩小文件系统

    缩小为10G

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    ➜  ~ resize2fs /dev/vg/lv 10G
    resize2fs 1.42.12 (29-Aug-2014)
    Please run 'e2fsck -f /dev/vg/lv' first.
    ➜  ~ resize2fs /dev/mapper/vg-lv 10G
    resize2fs 1.42.12 (29-Aug-2014)
    Please run 'e2fsck -f /dev/mapper/vg-lv' first.
    ➜  ~ e2fsck -f /dev/mapper/vg-lv
    e2fsck 1.42.12 (29-Aug-2014)
    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/vg-lv: 11/1376256 files (0.0% non-contiguous), 130401/5505024 blocks
    ➜  ~ resize2fs /dev/mapper/vg-lv 10G
    resize2fs 1.42.12 (29-Aug-2014)
    Resizing the filesystem on /dev/mapper/vg-lv to 2621440 (4k) blocks.
    The filesystem on /dev/mapper/vg-lv is now 2621440 (4k) blocks long.

  3. 缩小LV

    缩小的容量为之前的容量减去文件系统容量
    21-10=11

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    ➜  ~ lvreduce -L -11G /dev/vg/lv
      WARNING: Reducing active logical volume to 10.00 GiB
      THIS MAY DESTROY YOUR DATA (filesystem etc.)
    Do you really want to reduce lv? [y/n]: y
      Size of logical volume vg/lv changed from 21.00 GiB (5376 extents) to 10.00 GiB (2560 extents).
      Logical volume lv successfully resized

  4. 查看缩小后的LV

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    ➜  ~ lvdisplay
      --- Logical volume ---
      LV Path                /dev/vg/lv
      LV Name                lv
      VG Name                vg
      LV UUID                5q9mCJ-7Y3f-dEo7-xlDz-lJAW-Oczm-RuCeIE
      LV Write Access        read/write
      LV Creation host, time kali, 2016-08-03 09:51:18 +0800
      LV Status              available
      # open                 0
      LV Size                10.00 GiB
      Current LE             2560
      Segments               1
      Allocation             inherit
      Read ahead sectors     auto
      - currently set to     256
      Block device           254:0

  5. 挂载

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    ➜  ~ mount /dev/vg/lv /mnt
    ➜  ~ mount | tail -n 1
    /dev/mapper/vg-lv on /mnt type ext4 (rw,relatime,data=ordered)

缩小卷组

  1. 将一个PV从制定卷组中移除

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    ➜  ~ vgreduce vg /dev/sdc
      Removed "/dev/sdc" from volume group "vg"

  2. 查看缩小后的卷组大小

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    ~ vgdisplay
    --- Volume group ---
    VG Name               vg
    System ID             
    Format                lvm2
    Metadata Areas        1
    Metadata Sequence No  8
    VG Access             read/write
    VG Status             resizable
    MAX LV                0
    Cur LV                1
    Open LV               1
    Max PV                0
    Cur PV                1
    Act PV                1
    VG Size               50.00 GiB
    PE Size               4.00 MiB
    Total PE              12799
    Alloc PE / Size       2560 / 10.00 GiB
    Free  PE / Size       10239 / 40.00 GiB
    VG UUID               E32ZJW-3NqL-jpr2-1KYN-QWDh-dZhJ-1ZxZ2i

  3. 移除物理卷

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    ➜  ~ pvs
      PV         VG   Fmt  Attr PSize  PFree
      /dev/sdb   vg   lvm2 a--  50.00g 40.00g
      /dev/sdc        lvm2 ---  20.00g 20.00g
    ➜  ~ pvremove /dev/sdc
      Labels on physical volume "/dev/sdc" successfully wiped
    ➜  ~ pvs
      PV         VG   Fmt  Attr PSize  PFree
      /dev/sdb   vg   lvm2 a--  50.00g 40.00g
    ➜  ~
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