LVM常用操作

发布时间：2015-11-06 16:48:28作者：知识屋

一、LVM是什么

LVM是 Logical Volume Manager（逻辑卷管理）的简写，简单的说LVM可以跨分区存储数据，并且LVM可以在无需停机的状态下动态调整分区的大小。

二、基本术语

*物理存储介质（PhysicalStorageMedia）

指系统的物理存储设备：磁盘，如：/dev/hda、/dev/sda等，是存储系统最底层的存储单元。

*物理卷（Physical Volume，PV）

指磁盘分区或从逻辑上与磁盘分区具有同样功能的设备（如RAID），是LVM的基本存储逻辑块，但和基本的物理存储介质（如分区、磁盘等）比较，却包含有与LVM相关的管理参数。

*卷组（Volume Group，VG）

类似于非LVM系统中的物理磁盘，其由一个或多个物理卷PV组成。可以在卷组上创建一个或多个LV（逻辑卷）。

*逻辑卷（Logical Volume，LV）

类似于非LVM系统中的磁盘分区，逻辑卷建立在卷组VG之上。在逻辑卷LV之上可以建立文件系统（比如/home或者/usr等）。

*物理块（Physical Extent，PE）

每一个物理卷PV被划分为称为PE（Physical Extents）的基本单元，具有唯一编号的PE是可以被LVM寻址的最小单元。PE的大小是可配置的，默认为4MB。所以物理卷（PV）由大小等同的基本单元PE组成。

*逻辑块（Logical Extent，LE）

逻辑卷LV也被划分为可被寻址的基本单位，称为LE。在同一个卷组中，LE的大小和PE是相同的，并且一一对应。如图（1）

三、创建管理

常用管理命令如下：

管理lv:

pv: pvcreate, pvdisplay, pvs, pvscan, pvremove, pvmove

vg: vgcreate, vgdisplay, vgs, vgscan, vgremove, vgextend, vgreduce

lv: lvcreate, lvdisplay, lvs, lvresize, lvextend, lvreduce, lvremove

1、PV相关操作

创建pv

1.1、如图（2）使用fdisk创建物理磁盘分区

[root@www ~]# fdisk -l /dev/sdb

Disk /dev/sdb: 21.5 GB, 21474836480 bytes

255 heads, 63 sectors/track, 2610 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0xd9180e6e

Device Boot Start End Blocks Id System

/dev/sdb1 1 262 2104483+ 8e Linux LVM

/dev/sdb2 263 655 3156772+ 8e Linux LVM

[root@www ~]#

创建物理卷

pvcreate

[root@www ~]# pvcreate /dev/sdb1 /dev/sdb2//创建PV   Physical volume "/dev/sdb1" successfully created  Physical volume "/dev/sdb2" successfully created

查看PV

[root@www ~]# pvs//查看PV  PV         VG   Fmt  Attr PSize  PFree  /dev/sda2  vg0  lvm2 a--  59.99g 7.99g  /dev/sdb1       lvm2 ---   2.01g 2.01g  /dev/sdb2       lvm2 ---   3.01g 3.01g[root@www ~]# pvdisplay /dev/sdb[0-9]//可以看到详细信息  --- Physical volume ---  PV Name               /dev/sdb1  VG Name               myvg  PV Size               2.01 GiB / not usable 3.16 MiB  Allocatable           yes   PE Size               4.00 MiB  Total PE              513  Free PE               513  Allocated PE          0  PV UUID               rA5Vdy-j2rr-b9Vf-zo8I-sjFD-1z23-VhHAgI      --- Physical volume ---  PV Name               /dev/sdb2  VG Name               myvg  PV Size               3.01 GiB / not usable 2.79 MiB  Allocatable           yes   PE Size               4.00 MiB  Total PE              770  Free PE               770  Allocated PE          0  PV UUID               GVtLyK-Ugd1-DKHo-3wHS-oia1-lbpz-PA4oma    [root@www ~]#

删除pv

[root@www ~]# pvcreate /dev/sdb3   //创建pv  Physical volume "/dev/sdb3" successfully created[root@www ~]# pvs   //查看pv  PV         VG   Fmt  Attr PSize  PFree  /dev/sda2  vg0  lvm2 a--  59.99g 7.99g  /dev/sdb1  myvg lvm2 a--   2.00g    0   /dev/sdb2  myvg lvm2 a--   3.01g 2.01g  /dev/sdb3       lvm2 ---   3.01g 3.01g[root@www ~]# pvremove /dev/sdb3   //删除pv /dev/sdb3  Labels on physical volume "/dev/sdb3" successfully wiped[root@www ~]# pvs  PV         VG   Fmt  Attr PSize  PFree  /dev/sda2  vg0  lvm2 a--  59.99g 7.99g  /dev/sdb1  myvg lvm2 a--   2.00g    0   /dev/sdb2  myvg lvm2 a--   3.01g 2.01g

2、VG相关操作

创建VG

vgcreate

# vgcreate VGNAME /dev/PV1...

[-s|--physicalextentsize PhysicalExtentSize[bBsSkKmMgGtTpPeE]] //指定PE大小

[-t|--test] //测试，不真正创建

[-v|--verbose]//显示创建过程

[root@www ~]# vgcreate myvg /dev/sdb{1,2}  Volume group "myvg" successfully created

查看VG

[root@www ~]# vgs  VG   #PV #LV #SN Attr   VSize  VFree  myvg   2   0   0 wz--n-  5.01g 5.01g  vg0    1   4   0 wz--n- 59.99g 7.99g[root@www ~]# vgdisplay   --- Volume group ---  VG Name               myvg  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               5.01 GiB  PE Size               4.00 MiB  //PE 块大小  Total PE              1283  Alloc PE / Size       0 / 0     Free  PE / Size       1283 / 5.01 GiB  VG UUID               llSGpO-Bk51-KVBB-llAZ-AA9E-aBYq-sUrnPL

删除vg

# vgremove VGNAME...[root@www ~]# vgs  VG   #PV #LV #SN Attr   VSize  VFree  myvg   2   0   0 wz--n-  5.01g 5.01g  vg0    1   4   0 wz--n- 59.99g 7.99g[root@www ~]# vgremove myvg//删除vg  Volume group "myvg" successfully removed[root@www ~]# vgs  VG   #PV #LV #SN Attr   VSize  VFree  vg0    1   4   0 wz--n- 59.99g 7.99g[root@www ~]#

缩减VG：通过从vg中移除pv实现

注意：计划移除的pv不能包含已经存储数据的pe；如果有需要先使用pvmove移动到同vg内其它pv上；

[root@www ~]# vgcreate myvg /dev/sdb{1,2}  Volume group "myvg" successfully created[root@www ~]# vgdisplay   --- Volume group ---  VG Name               myvg  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               5.01 GiB//大小为5G  PE Size               4.00 MiB  Total PE              1283  Alloc PE / Size       0 / 0     Free  PE / Size       1283 / 5.01 GiB  VG UUID               Iz9bc0-Sw38-H916-TAg3-abNh-iUJW-hjuRoB------------------------------------------------------------------------------

我们要在myvg中移除/dev/sdb2 【缩减vg要保证缩减后的vg大小能够存储原来的数据】

[root@www ~]# pvmove /dev/sdb2  // 将/sdb2中的数据移动到其他pv上  No data to move for myvg[root@www ~]# vgreduce myvg /dev/sdb2//移除/dev/sdb2  Removed "/dev/sdb2" from volume group "myvg"[root@www ~]# vgdisplay myvg  --- Volume group ---  VG Name               myvg  System ID               Format                lvm2  Metadata Areas        1  Metadata Sequence No  2  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               2.00 GiB// 大小变为2G  PE Size               4.00 MiB  Total PE              513  Alloc PE / Size       0 / 0     Free  PE / Size       513 / 2.00 GiB  VG UUID               Iz9bc0-Sw38-H916-TAg3-abNh-iUJW-hjuRoB

-----------------------

扩展VG：向VG中添加更多的PV来实现

vgextend

[root@www ~]# vgs  VG   #PV #LV #SN Attr   VSize  VFree  myvg   1   0   0 wz--n-  2.00g 2.00g//扩展前大小为2G  vg0    1   4   0 wz--n- 59.99g 7.99g[root@www ~]# vgextend myvg /dev/sdb2//向myvg中添加/dev/sdb2  Volume group "myvg" successfully extended[root@www ~]# vgs  VG   #PV #LV #SN Attr   VSize  VFree  myvg   2   0   0 wz--n-  5.01g 5.01g//大小变为5G  vg0    1   4   0 wz--n- 59.99g 7.99g

3、LV相关操作

创建LV Logical Volume

创建lv:

lvcreate -L #[bBsSkKmMgGtTpPeE] [-n|--name LogicalVolume{Name|Path}] VG_NAME

LV设备路径：

(1) /dev/VGNAME/LVNAME

(2) /dev/mapper/VGNAME-LVNAME

实际路径：/dev/dm-#

注意：lv的大小必须为pe的整数倍

[root@www ~]# lvcreate -L 4G -n mylv myvg//创建大小为4G的LV 名字为mylv  Logical volume "mylv" created[root@www ~]# lvs//查看LV  LV   VG   Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert  mylv myvg -wi-a-----  4.00g           //大小为4G                                           root vg0  -wi-ao---- 20.00g                                                      swap vg0  -wi-ao----  2.00g                                                      usr  vg0  -wi-ao---- 10.00g                                                      var  vg0  -wi-ao---- 20.00g                                                    [root@www ~]# lvdisplay   --- Logical volume ---  LV Path                /dev/myvg/mylv  LV Name                mylv  VG Name                myvg  LV UUID                i3tDAL-GdB4-TVIf-Efun-vVmg-Ig00-cSCdKk  LV Write Access        read/write  LV Creation host, time www.w1.com, 2015-08-16 05:05:40 +0800  LV Status              available  # open                 0  LV Size                4.00 GiB  Current LE             1024  Segments               2  Allocation             inherit  Read ahead sectors     auto  - currently set to     256  Block device           253:4

移除LV

lvremove LV_PATH

[root@www ~]# lvs  LV   VG   Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert  mylv myvg -wi-a-----  4.00g          //查看lv                                            root vg0  -wi-ao---- 20.00g                                                      swap vg0  -wi-ao----  2.00g                                                      usr  vg0  -wi-ao---- 10.00g                                                      var  vg0  -wi-ao---- 20.00g                                                    [root@www ~]# lvremove /dev/myvg/mylv//移除mylvDo you really want to remove active logical volume mylv? [y/n]: y  Logical volume "mylv" successfully removed[root@www ~]# lvs  LV   VG   Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert  root vg0  -wi-ao---- 20.00g             //已经不存在mylv                                         swap vg0  -wi-ao----  2.00g                                                      usr  vg0  -wi-ao---- 10.00g                                                      var  vg0  -wi-ao---- 20.00g                                                    [root@www ~]#

扩展LV

存储设备有：物理边界

文件系统有：逻辑边界

扩展：先扩展物理边界，而后拉伸逻辑边界

lvextend, lvresize

resize2fs

扩展LV步骤

1、先确定目标大小：要确保此lv所在vg中有足够的空闲可用；

2G --> 4G

+2G

2、扩展物理边界

lvextend -L [+]#[bBsSkKmMgGtTpPeE] /dev/VGNAME/LVNAME

3、拉伸逻辑边界

resize2fs /dev/VGNAME/LVNAME

例：先创建大小为2G的LV然后在扩展为4G

[root@www ~]# lvcreate -L 2G -n mylv myvg  Logical volume "mylv" created[root@www ~]# lvdisplay /dev/myvg/mylv  --- Logical volume ---  LV Path                /dev/myvg/mylv  LV Name                mylv  VG Name                myvg  LV UUID                yZE2SK-G9J9-dFdH-uJvK-Lln6-AS2G-UqHMjU  LV Write Access        read/write  LV Creation host, time www.w1.com, 2015-08-16 05:12:04 +0800  LV Status              available  # open                 0  LV Size                2.00 GiB  Current LE             512  Segments               1  Allocation             inherit  Read ahead sectors     auto  - currently set to     256  Block device           253:4

格式化/myvg/mylv

[root@www ~]# mke2fs -t ext4 /dev/myvg/mylvmke2fs 1.41.12 (17-May-2010)Filesystem label=OS type: LinuxBlock size=4096 (log=2)Fragment size=4096 (log=2)Stride=0 blocks, Stripe width=0 blocks131072 inodes, 524288 blocks26214 blocks (5.00%) reserved for the super userFirst data block=0Maximum filesystem blocks=53687091216 block groups32768 blocks per group, 32768 fragments per group8192 inodes per groupSuperblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912Writing inode tables: done                            Creating journal (16384 blocks): doneWriting superblocks and filesystem accounting information: doneThis filesystem will be automatically checked every 38 mounts or180 days, whichever comes first.  Use tune2fs -c or -i to override.

[root@www ~]# mkdir /nyist//创建挂载点[root@www ~]# mount /dev/myvg/mylv /nyist//挂载[root@www ~]# df -h//查看大小Filesystem            Size  Used Avail Use% Mounted on/dev/mapper/vg0-root   20G   18G  908M  96% /tmpfs                 565M     0  565M   0% /dev/shm/dev/sda1             190M   33M  148M  18% /boot/dev/mapper/vg0-usr   9.8G  2.4G  6.9G  26% /usr/dev/mapper/vg0-var    20G  294M   19G   2% /var/dev/sda3              59G  4.7G   52G   9% /usr/soc/dev/mapper/myvg-mylv                      2.0G  3.0M  1.9G   1% /nyist

[root@www ~]# cp /etc/fstab /nyist

查看文件

[root@www ~]# cat /nyist/fstab ## /etc/fstab# Created by anaconda on Thu Mar 26 20:01:38 2015## Accessible filesystems, by reference, are maintained under '/dev/disk'# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info#/dev/mapper/vg0-root    /                       ext4    defaults        1 1UUID=0d0698ff-1645-4ff8-af27-fc6e73573941 /boot                   ext4    defaults        1 2/dev/mapper/vg0-usr     /usr                    ext4    defaults        1 2/dev/mapper/vg0-var     /var                    ext4    defaults        1 2/dev/mapper/vg0-swap    swap                    swap    defaults        0 0tmpfs                   /dev/shm                tmpfs   defaults        0 0devpts                  /dev/pts                devpts  gid=5,mode=620  0 0sysfs                   /sys                    sysfs   defaults        0 0proc                    /proc                   proc    defaults        0 0/dev/sda3           /usr/soc                ext4    defaults        0 0[root@www ~]#

查看VG剩余空间：

[root@www ~]# vgs  VG   #PV #LV #SN Attr   VSize  VFree  myvg   2   1   0 wz--n-  5.01g 3.01g//还有3G 我们要扩展到4G 容量足够  vg0    1   4   0 wz--n- 59.99g 7.99g

扩展物理边界

[root@www ~]# lvs /dev/myvg/mylv  LV   VG   Attr       LSize Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert  mylv myvg -wi-a----- 2.00g          //目前大小为2G                                          [root@www ~]# lvextend -L 4G  /dev/myvg/mylv  //扩展LV 也可以写为： lvextend -L +2G /vev/myvg/mylv  Size of logical volume myvg/mylv changed from 2.00 GiB (512 extents) to 4.00 GiB (1024 extents).  Logical volume mylv successfully resized[root@www ~]# lvs /dev/myvg/mylv查看mylv大小  LV   VG   Attr       LSize Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert  mylv myvg -wi-a----- 4.00g              //扩展为4G                                      [root@www ~]# [root@www ~]# lvdisplay /dev/myvg/mylv  --- Logical volume ---  LV Path                /dev/myvg/mylv  LV Name                mylv  VG Name                myvg  LV UUID                yZE2SK-G9J9-dFdH-uJvK-Lln6-AS2G-UqHMjU  LV Write Access        read/write  LV Creation host, time www.w1.com, 2015-08-16 05:12:04 +0800  LV Status              available  # open                 0  LV Size                4.00 GiB  //已经扩展为4G  Current LE             1024  Segments               2  Allocation             inherit  Read ahead sectors     auto  - currently set to     256  Block device           253:4

查看逻辑空间大小

[root@www ~]# df -hFilesystem            Size  Used Avail Use% Mounted on....../dev/sda3              59G  4.7G   52G   9% /usr/soc/dev/mapper/myvg-mylv                      2.0G  3.1M  1.9G   1% /nyist//依然为2G[root@www ~]#

拉伸逻辑边界

[root@www ~]# resize2fs /dev/myvg/mylv//扩展逻辑边界resize2fs 1.41.12 (17-May-2010)Filesystem at /dev/myvg/mylv is mounted on /nyist; on-line resizing requiredold desc_blocks = 1, new_desc_blocks = 1Performing an on-line resize of /dev/myvg/mylv to 1048576 (4k) blocks.The filesystem on /dev/myvg/mylv is now 1048576 blocks long.[root@www ~]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/mapper/vg0-root   20G   18G  908M  96% /tmpfs                 565M     0  565M   0% /dev/shm/dev/sda1             190M   33M  148M  18% /boot/dev/mapper/vg0-usr   9.8G  2.4G  6.9G  26% /usr/dev/mapper/vg0-var    20G  294M   19G   2% /var/dev/sda3              59G  4.7G   52G   9% /usr/soc/dev/mapper/myvg-mylv                      3.9G  4.0M  3.7G   1% /nyist//大小已经为3.9G 成功扩展[root@www ~]#

============================================================

缩减LV

注意：

1、缩减LV必须要离线

2、必须先缩减文件系统，然后再缩减LV大小

过程：

1、先确定缩减后的目标大小：要确保缩减后的大小能够容纳现在的所有数据；

2、卸载逻辑卷，并强制做文件系统一致性检查；

e2fsck -f /dev/VGNAME/LVNAME

3、缩减逻辑边界

resize2fs /dev/VGNAME/LVNAME #[bBsSkKmMgGtTpPeE]

// resize2fs /dev/myvg/mylv 3G

4、缩减物理边界

lvreduce -L [-]#[bBsSkKmMgGtTpPeE] /dev/VGNAME/LVNAME

//lvreduce -L 3G /dev/myvg/mylv //缩减到3G

eg:

[root@www ~]# umount /nyist[root@www ~]# e2fsck -f /dev/myvg/mylve2fsck 1.41.12 (17-May-2010)Pass 1: Checking inodes, blocks, and sizesPass 2: Checking directory structurePass 3: Checking directory connectivityPass 4: Checking reference countsPass 5: Checking group summary information/dev/myvg/mylv: 12/262144 files (0.0% non-contiguous), 33871/1048576 blocks[root@www ~]# resize2fs /dev/myvg/mylv 3G//缩减逻辑边界resize2fs 1.41.12 (17-May-2010)Resizing the filesystem on /dev/myvg/mylv to 786432 (4k) blocks.The filesystem on /dev/myvg/mylv is now 786432 blocks long.[root@www ~]# lvreduce -L 3G /dev/myvg/mylv//缩减物理边界  WARNING: Reducing active logical volume to 3.00 GiB  THIS MAY DESTROY YOUR DATA (filesystem etc.)Do you really want to reduce mylv? [y/n]: y  Size of logical volume myvg/mylv changed from 4.00 GiB (1024 extents) to 3.00 GiB (768 extents).  Logical volume mylv successfully resized[root@www ~]#

验证：

[root@www ~]# lvs  LV   VG   Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert  mylv myvg -wi-a-----  3.00g          //大小3G                                            root vg0  -wi-ao---- 20.00g                                                      swap vg0  -wi-ao----  2.00g                                                      usr  vg0  -wi-ao---- 10.00g                                                      var  vg0  -wi-ao---- 20.00g                                                    [root@www ~]# mount /dev/myvg/mylv /nyist[root@www ~]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/mapper/vg0-root   20G   18G  908M  96% /tmpfs                 565M     0  565M   0% /dev/shm/dev/sda1             190M   33M  148M  18% /boot/dev/mapper/vg0-usr   9.8G  2.4G  6.9G  26% /usr/dev/mapper/vg0-var    20G  294M   19G   2% /var/dev/sda3              59G  4.7G   52G   9% /usr/soc/dev/mapper/myvg-mylv                      2.9G  3.1M  2.8G   1% /nyist//大小2.9G   [root@www ~]#

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