lvm使用

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LVM(Logic Volume Manager)逻辑卷管理，它是linux环境下对磁盘分区进行管理的一种机制。

TODO

基本术语

  • PV: Physical Volume 物理卷
  • VG: Volume Group 卷组，由一个或多个PV组成。可以在其上创建一个或多个LV
  • LV: Logical Volume 逻辑卷，在其上可以创建文件系统
  • PE: Physical Extent 物理扩展盘区，每个PV都会被划分成PE，它是可以被LVM寻址的最小单元
  • LE: Logical Extent 逻辑扩展盘区，

基本原理

1) 物理磁盘被格式化为PV，空间被划分为一个个PE
2) 不同的PV加入到同一个VG中，其对应的所有PE都进入VG的PE池中
3) LVM从PE池中选择PE创建LV，不同物理盘中的PE可能会划分到同一个LV中
4) 在LV上创建文件系统后就可以挂载使用了
5) 对LV的扩容和缩减其实就是相应的增加或减少PE数量

创建逻辑卷时，定义了逻辑扩展盘区与物理扩展盘区的映射关系。

创建流程

创建分区

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[root@localhost ~]# 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): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): p
Partition number (1-4, default 1): 
First sector (2048-2097151, default 2048): 
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-2097151, default 2097151): +300M
Partition 1 of type Linux and of size 300 MiB is set

Command (m for help): p

Disk /dev/sdb: 1073 MB, 1073741824 bytes, 2097152 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: 0x233e2ebd

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048      616447      307200   83  Linux

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): p

Disk /dev/sdb: 1073 MB, 1073741824 bytes, 2097152 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: 0x233e2ebd

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048      616447      307200   8e  Linux LVM

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

Calling ioctl() to re-read partition table.
Syncing disks.

创建pv

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[root@localhost ~]# pvcreate /dev/sdb1
  Physical volume "/dev/sdb1" successfully created.
[root@localhost ~]# pvs
  PV         VG     Fmt  Attr PSize   PFree  
  /dev/sdb1         lvm2 ---  300.00m 300.00m
[root@localhost ~]# pvdisplay /dev/sdb1
  --- Physical volume ---
  PV Name               /dev/sdb1
  VG Name               vg0
  PV Size               300.00 MiB / not usable 4.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              74
  Free PE               74
  Allocated PE          0
  PV UUID               8dqEi7-haMt-ciIM-ib2e-AUxp-f7ym-bCvlfw

创建vg

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[root@localhost ~]# vgcreate vg0 /dev/sdb1
  Volume group "vg0" successfully created
[root@localhost ~]# vgs
  VG     #PV #LV #SN Attr   VSize   VFree  
  vg0      1   0   0 wz--n- 296.00m 296.00m
[root@localhost ~]# vgdisplay vg0
  --- Volume group ---
  VG Name               vg0
  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               296.00 MiB
  PE Size               4.00 MiB
  Total PE              74
  Alloc PE / Size       0 / 0           #已分配的PE数量
  Free  PE / Size       74 / 296.00 MiB #剩余的PE数量
  VG UUID               3FH6og-yXLt-NaL3-uehk-9lrJ-c4TD-r0z6Sa

创建lv

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[root@localhost ~]# lvcreate -L 100m -n lv0 vg0
  Logical volume "lv0" created.
[root@localhost ~]# lvs
  LV   VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv0  vg0    -wi-a----- 100.00m  
[root@localhost ~]# lvdisplay /dev/vg0/lv0 
  --- Logical volume ---
  LV Path                /dev/vg0/lv0
  LV Name                lv0
  VG Name                vg0
  LV UUID                Plb1kl-JGcg-0UfR-W3Ue-tDBc-D5Tc-tj6X0n
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2019-05-16 02:02:27 +0800
  LV Status              available
  # open                 0
  LV Size                100.00 MiB
  Current LE             25
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:2

[root@localhost ~]# pvdisplay /dev/sdb1
  --- Physical volume ---
  PV Name               /dev/sdb1
  VG Name               vg0
  PV Size               300.00 MiB / not usable 4.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              74
  Free PE               49
  Allocated PE          25    # 可以看到已经有PE被分配出去了
  PV UUID               8dqEi7-haMt-ciIM-ib2e-AUxp-f7ym-bCvlfw
[root@localhost ~]# vgdisplay vg0
  --- Volume group ---
  VG Name               vg0
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               296.00 MiB
  PE Size               4.00 MiB
  Total PE              74
  Alloc PE / Size       25 / 100.00 MiB   # 可以看到已经有PE被分配出去了
  Free  PE / Size       49 / 196.00 MiB
  VG UUID               3FH6og-yXLt-NaL3-uehk-9lrJ-c4TD-r0z6Sa

创建LV时LV的大小有以下两种方式指定

  • 通过-L参数，表示物理大小
  • 通过-l参数，使用相关VG/LV或PV大小的百分比来指定
    • 10%VG, 表示10%的VG总大小
    • 20%FREE, 表示VG中剩余空间的20%
    • 30%PVS, 表示PV集合中剩余空间的30%
    • 该参数后面跟数值(非百分比)时，表示包含多少个PE大小。
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[root@localhost ~]# lvremove /dev/vg0/lv0
Do you really want to remove active logical volume vg0/lv0? [y/n]: y
  Logical volume "lv0" successfully removed
[root@localhost ~]# lvcreate -l 30%VG -n lv1 vg0
  Logical volume "lv1" created.
[root@localhost ~]# lvs
  LV   VG     Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv1  vg0    -wi-a----- 88.00m                                                    
[root@localhost ~]# vgs
  VG     #PV #LV #SN Attr   VSize   VFree  
  centos   1   2   0 wz--n-  <9.00g      0 
  vg0      1   1   0 wz--n- 296.00m 208.00m
[root@localhost ~]#

格式化文件系统

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[root@localhost ~]# mkfs.ext3 /dev/vg0/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
22528 inodes, 90112 blocks
4505 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
11 block groups
8192 blocks per group, 8192 fragments per group
2048 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 

[root@localhost ~]# fdisk -l /dev/vg0/lv1 

Disk /dev/vg0/lv1: 92 MB, 92274688 bytes, 180224 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

[root@localhost ~]# mkdir /usr1
[root@localhost ~]# mount /dev/vg0/lv1 /usr1
[root@localhost ~]# df -ha
Filesystem               Size  Used Avail Use% Mounted on
/dev/mapper/vg0-lv1       82M  1.6M   76M   2% /usr1
[root@localhost ~]#

扩容

扩容LV

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[root@localhost ~]# lvs
  LV   VG     Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv1  vg0    -wi-ao---- 88.00m                                                    
[root@localhost ~]# lvextend -L +100m /dev/vg0/lv1 
  Size of logical volume vg0/lv1 changed from 88.00 MiB (22 extents) to 188.00 MiB (47 extents).
  Logical volume vg0/lv1 successfully resized.
[root@localhost ~]# lvs
  LV   VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv1  vg0    -wi-ao---- 188.00m 
[root@localhost ~]# df -ha
Filesystem               Size  Used Avail Use% Mounted on
/dev/mapper/vg0-lv1       82M  1.6M   76M   2% /usr1    # LV已经扩容但是文件系统大小还时原来大小
[root@localhost ~]# resize2fs /dev/vg0/lv1 
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/vg0/lv1 is mounted on /usr1; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/vg0/lv1 is now 192512 blocks long.
[root@localhost ~]# df -ha
Filesystem               Size  Used Avail Use% Mounted on
/dev/mapper/vg0-lv1      178M  1.6M  169M   1% /usr1    # 已经扩容
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[root@localhost ~]# lvs |grep lv1
  lv1  vg0    -wi-ao---- 188.00m                                                    
[root@localhost ~]# lvextend -l +50%FREE /dev/vg0/lv1 
  Size of logical volume vg0/lv1 changed from 188.00 MiB (47 extents) to 244.00 MiB (61 extents).
  Logical volume vg0/lv1 successfully resized.
[root@localhost ~]# lvs |grep lv1
  lv1  vg0    -wi-ao---- 244.00m                                                    
[root@localhost ~]# df -ha |grep lv1
/dev/mapper/vg0-lv1      178M  1.6M  169M   1% /usr1
[root@localhost ~]# resize2fs /dev/mapper/vg0-lv1 
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/mapper/vg0-lv1 is mounted on /usr1; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/mapper/vg0-lv1 is now 249856 blocks long.
[root@localhost ~]# df -ha |grep lv1
/dev/mapper/vg0-lv1      233M  2.1M  220M   1% /usr1

lvextend 中 -L 和 -l 参数中如果没有使用 + 号，则表示扩容到指定大小

扩容VG

当VG中没有空闲资源时需要先扩容VG才能扩容LV

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[root@localhost ~]# pvs
  PV         VG     Fmt  Attr PSize   PFree 
  /dev/sdb1  vg0    lvm2 a--  296.00m 52.00m
[root@localhost ~]# pvcreate /dev/sdc1 
  Physical volume "/dev/sdc1" successfully created.
[root@localhost ~]# pvs
  PV         VG     Fmt  Attr PSize   PFree
  /dev/sdb1  vg0    lvm2 a--  296.00m  52.00m
  /dev/sdc1         lvm2 ---  511.00m 511.00m
[root@localhost ~]# vgs
  VG     #PV #LV #SN Attr   VSize   VFree 
  vg0      1   1   0 wz--n- 296.00m 52.00m
[root@localhost ~]# vgextend vg0 /dev/sdc1 
  Volume group "vg0" successfully extended
[root@localhost ~]# vgs
  VG     #PV #LV #SN Attr   VSize   VFree  
  vg0      2   1   0 wz--n- 804.00m 560.00m
[root@localhost ~]# 
[root@localhost ~]# lvs
  LV   VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv1  vg0    -wi-a----- 244.00m
[root@localhost ~]# lvextend -l +100%FREE /dev/vg0/lv1 
  Size of logical volume vg0/lv1 changed from 244.00 MiB (61 extents) to 804.00 MiB (201 extents).
  Logical volume vg0/lv1 successfully resized.
[root@localhost ~]# lvs
  LV   VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv1  vg0    -wi-a----- 804.00m

缩减容量

  • 先umount设备
  • 缩减文件系统大小
  • 缩减LV大小
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[root@localhost ~]# umount -l /usr1
[root@localhost ~]# resize2fs /dev/mapper/vg0-lv1 100M
resize2fs 1.42.9 (28-Dec-2013)
Please run 'e2fsck -f /dev/mapper/vg0-lv1' first.
[root@localhost ~]# e2fsck -f /dev/mapper/vg0-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/mapper/vg0-lv1: 2369/206848 files (6.4% non-contiguous), 61211/823296 blocks
[root@localhost ~]# 
[root@localhost ~]# resize2fs /dev/mapper/vg0-lv1 100M
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/mapper/vg0-lv1 to 102400 (1k) blocks.
The filesystem on /dev/mapper/vg0-lv1 is now 102400 blocks long.
[root@localhost ~]# lvreduce -L 100M /dev/mapper/vg0-lv1 
  WARNING: Reducing active logical volume to 100.00 MiB.
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce vg0/lv1? [y/n]: y
  Size of logical volume vg0/lv1 changed from 804.00 MiB (201 extents) to 100.00 MiB (25 extents).
  Logical volume vg0/lv1 successfully resized.
[root@localhost ~]# lvs
  LV   VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv1  vg0    -wi-a----- 100.00m  
[root@localhost /]# vgs
  VG     #PV #LV #SN Attr   VSize   VFree  
  vg0      2   1   0 wz--n- 804.00m 704.00m
[root@localhost /]# pvs
  PV         VG     Fmt  Attr PSize   PFree  
  /dev/sdb1  vg0    lvm2 a--  296.00m 196.00m
  /dev/sdc1  vg0    lvm2 a--  508.00m 508.00m

分区扩展

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root@baoze:# pvs
  PV         VG        Fmt  Attr PSize   PFree
  /dev/sda3  ubuntu-vg lvm2 a--  <28.00g    0 
root@baoze:# lsblk 
NAME                      MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
loop1                       7:1    0   62M  1 loop /snap/core20/1587
loop2                       7:2    0 79.9M  1 loop /snap/lxd/22923
loop3                       7:3    0 49.6M  1 loop /snap/snapd/17883
loop4                       7:4    0 63.3M  1 loop /snap/core20/1778
loop5                       7:5    0  103M  1 loop /snap/lxd/23541
sda                         8:0    0   80G  0 disk        ###  当前sda总大小80G
├─sda1                      8:1    0    1M  0 part 
├─sda2                      8:2    0    2G  0 part /boot
└─sda3                      8:3    0   28G  0 part        ### 但是sd3只有28G
  └─ubuntu--vg-ubuntu--lv 253:0    0   28G  0 lvm  /
sr0                        11:0    1  1.4G  0 rom

#### 把sda中空闲的区域扩展到sd3中
root@baoze:# growpart /dev/sda 3
CHANGED: partition=3 start=4198400 old: size=58714112 end=62912512 new: size=163573727 end=167772127
root@baoze:# lsblk
NAME                      MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
loop1                       7:1    0   62M  1 loop /snap/core20/1587
loop2                       7:2    0 79.9M  1 loop /snap/lxd/22923
loop3                       7:3    0 49.6M  1 loop /snap/snapd/17883
loop4                       7:4    0 63.3M  1 loop /snap/core20/1778
loop5                       7:5    0  103M  1 loop /snap/lxd/23541
sda                         8:0    0   80G  0 disk 
├─sda1                      8:1    0    1M  0 part 
├─sda2                      8:2    0    2G  0 part /boot
└─sda3                      8:3    0   78G  0 part          ### 当前sd3中的空间已经扩展到78G
  └─ubuntu--vg-ubuntu--lv 253:0    0   28G  0 lvm  /
sr0                        11:0    1  1.4G  0 rom
root@baoze:# pvs
  PV         VG        Fmt  Attr PSize   PFree 
  /dev/sda3  ubuntu-vg lvm2 a--  <78.00g 50.00g     ### pvs中也可以看到空闲的PE了