LVM 管理

创建LVM

划分分区,并指定适合的LVM的ID
[root@centos6 rf]# fdisk/dev/sdc使用fdisk划分一个分区；也可直接拿块新硬盘直接创建LVM逻辑卷

Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x3ca76d2c.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): p 查看/dev/sdc硬盘的分区情况；由于是新硬盘所以没有分区表

Disk /dev/sdc: 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: 0x3ca76d2c

   Device Boot      Start         End      Blocks   Id  System

Command (m for help): n 表示创建一个分区
Command action
   e   extended
   p   primary partition (1-4)
p   表示主分区  MBR分区表最多只允许4个主分区或3个主分区加一个扩展分区，可以扩展分区创建多个逻辑分区（e|p） e表示扩展分区；p表示主分区
Partition number (1-4): 1   分区号
First cylinder (1-2610, default 1):   指定开始的柱面这里如果不指定表示选择的是默认柱面，扩展分区不要让系统默认否则会出错
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): +10G  创建的大小可以指定柱面 也可以指定空间的大小

Command (m for help): t 调整分区的ID
Selected partition 1
Hex code (type L to list codes): l 查看系统默认支持的所有分区ID

 0  Empty           24  NEC DOS         81  Minix / old Lin bf  Solaris        
 1  FAT12           39  Plan 9          82  Linux swap / So c1  DRDOS/sec (FAT-
 2  XENIX root      3c  PartitionMagic  83  Linux           c4  DRDOS/sec (FAT-
 3  XENIX usr       40  Venix 80286     84  OS/2 hidden C:  c6  DRDOS/sec (FAT-
 4  FAT16 <32M      41  PPC PReP Boot   85  Linux extended  c7  Syrinx         
 5  Extended        42  SFS             86  NTFS volume set da  Non-FS data    
 6  FAT16           4d  QNX4.x          87  NTFS volume set db  CP/M / CTOS / .
 7  HPFS/NTFS       4e  QNX4.x 2nd part 88  Linux plaintext de  Dell Utility   
 8  AIX             4f  QNX4.x 3rd part 8e  Linux LVM       df  BootIt         
 9  AIX bootable    50  OnTrack DM      93  Amoeba          e1  DOS access     
 a  OS/2 Boot Manag 51  OnTrack DM6 Aux 94  Amoeba BBT      e3  DOS R/O        
 b  W95 FAT32       52  CP/M            9f  BSD/OS          e4  SpeedStor      
 c  W95 FAT32 (LBA) 53  OnTrack DM6 Aux a0  IBM Thinkpad hi eb  BeOS fs        
 e  W95 FAT16 (LBA) 54  OnTrackDM6      a5  FreeBSD         ee  GPT            
 f  W95 Ext'd (LBA) 55  EZ-Drive        a6  OpenBSD         ef  EFI (FAT-12/16/
10  OPUS            56  Golden Bow      a7  NeXTSTEP        f0  Linux/PA-RISC b
11  Hidden FAT12    5c  Priam Edisk     a8  Darwin UFS      f1  SpeedStor      
12  Compaq diagnost 61  SpeedStor       a9  NetBSD          f4  SpeedStor      
14  Hidden FAT16 <3 63  GNU HURD or Sys ab  Darwin boot     f2  DOS secondary  
16  Hidden FAT16    64  Novell Netware  af  HFS / HFS+      fb  VMware VMFS    
17  Hidden HPFS/NTF 65  Novell Netware  b7  BSDI fs         fc  VMware VMKCORE 
18  AST SmartSleep  70  DiskSecure Mult b8  BSDI swap       fd  Linux raid auto
1b  Hidden W95 FAT3 75  PC/IX           bb  Boot Wizard hid fe  LANstep        
1c  Hidden W95 FAT3 80  Old Minix       be  Solaris boot    ff  BBT            
1e  Hidden W95 FAT1
Hex code (type L to list codes): 8e 这里选择8e 8e表示LVM
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): p 查看分区情况

Disk /dev/sdc: 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: 0x3ca76d2c

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1        1306    10490413+  8e  Linux LVM
Command (m for help): w保存退出
The partition table has been altered!

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

注意这里此磁盘分区已同步到内存中centos6新增磁盘同步分区表的
partx -a /dev/DEVICE 或者 kpartx -a /dev/DEVICE -f: force
centos6删除分区表同步的方法
partx -d --nr M-N /dev/DEVICE
CentOS 5 ，7: 增加分区或删除分区使用partprobe

分区已划分创建LVM

创建物理卷
[root@centos6 rf]# pvcreate /dev/sdc1
Physical volume "/dev/sdc1" successfully created
[root@centos6 rf]# pvdisplay 查看系统上所有的物理卷的详细信息

"/dev/sdc1" is a new physical volume of "10.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdc1
  VG Name                PV Size               10.00 GiB
  Allocatable           NO
   PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               n4NV1m-sr2p-A5K0-ckl4-681D-ah7g-HtYjmo

[root@centos6 rf]# pvs 显示系统上物理卷的信息

 PV         VG   Fmt  Attr PSize  PFree 
 /dev/sdc1       lvm2 ---- 10.00g 10.00g

[root@centos6 rf]# vgcreate -s 10M vg0 /dev/sdc1 创建卷组 -s 指定PE大小可以省略，省略表示选择默认值后面跟的是卷组的名字指定从哪个物理卷划分
Volume group "vg0" successfully created
[root@centos6 rf]# vgdisplay 查看卷组相关的信息

--- Volume group ---
 VG Name               vg0   卷组名称
 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               10.00 GiB 卷组总大小
 PE Size               10.00 MiB PE大小
 Total PE              1024 PE个数
 Alloc PE / Size       0 / 0   
 Free  PE / Size       1024 / 10.00 GiB
 VG UUID               ZujzGf-nNnJ-LfZb-ge6F-fiAP-MtHW-EepPhI

[root@centos6 rf]# vgs 查看系统中的卷组

VG   #PV #LV #SN Attr   VSize  VFree 
vg0    1   0   0 wz--n- 10.00g 10.00g

[root@centos6 rf]# lvcreate -L 10G -n cx vg0 创建逻辑卷 -L 表示指定空间大小 -n 表示指定逻辑卷的名字后面跟卷组名字表示从哪个卷组中划分逻辑分区

  Logical volume "cx" created.

[root@centos6 rf]# mkfs.ext4 /dev/vg0/cx 创建文件系统

mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
655360 inodes, 2621440 blocks
131072 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2684354560
80 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks: 
    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 30 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

[root@centos6 rf]# mkdir /cx 创建一个目录做挂载点
[root@centos6 rf]# vim /etc/fstab 编辑 /etc/fstab添加“UUID=d7ab49ba-156c-4ca4-8e57-d2c6e8dd3076 /cx ext4 defaults 1 0
”
[root@centos6 ~]# blkid /dev/vg0/cx 查看UUID

/dev/vg0/cx: UUID="d7ab49ba-156c-4ca4-8e57-d2c6e8dd3076" TYPE="ext4"

[root@centos6 rf]# mount -a 挂载/etc/fstab 文件中未挂载的设备
[root@centos6 rf]# mount 查看已挂载的设备

/dev/sda2 on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0")
/dev/sda1 on /boot type ext4 (rw)
/dev/sda6 on /home type ext4 (rw,usrquota)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
/dev/mapper/vg0-cx on /cx type ext4 (rw)

扩展LVM分区

1如果卷组里还有多余的空间，可以直接扩展逻辑卷；如果没有多余的空间就需要先扩展卷组
我这里先用一块新硬盘扩展物理卷再扩展卷组最后扩展逻辑分区
[root@centos6 ~]# pvcreate /dev/sdd # 扩展物理卷；如果有多余的物理卷，可以直接扩展卷组

  Physical volume "/dev/sdd" successfully created

[root@centos6 ~]# pvs 查看物理卷PV的信息

  PV         VG   Fmt  Attr PSize  PFree 
  /dev/sdc1  vg0  lvm2 a--u 10.00g     0 
  /dev/sdd        lvm2 ---- 60.00g 60.00g

[root@centos6 ~]# vgextend vg0 /dev/sdd 使用vgextend 扩展卷组（vg）后面跟卷组名指定把那个物理卷扩展到卷组

  Volume group "vg0" successfully extended

[root@centos6 ~]# vgdisplay

  --- Volume group ---
  VG Name               vg0  卷组名字
  System ID             
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               1
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               69.99 GiB 卷组总大小
  PE Size               10.00 MiB PE的大小
  Total PE              7167  PE个数
  Alloc PE / Size       1024 / 10.00 GiB  已分配的给逻辑卷（lv）使用的空间
  Free  PE / Size       6143 / 59.99 GiB  未分配空间
  VG UUID               ZujzGf-nNnJ-LfZb-ge6F-fiAP-MtHW-EepPhI

[root@centos6 ~]# lvextend -r -l +1000 /dev/vg0/cx 扩展逻辑卷并同步文件系统-r 表示同步文件系统

  Size of logical volume vg0/cx changed from 10.00 GiB (1024 extents) to 19.77 GiB (2024 extents).
  Logical volume cx successfully resized.
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/vg0-cx is mounted on /cx; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 2
Performing an on-line resize of /dev/mapper/vg0-cx to 5181440 (4k) blocks.
The filesystem on /dev/mapper/vg0-cx is now 5181440 blocks long.

注意扩展逻辑卷无需取消挂载;建议提前备份数据

缩减逻辑卷

先取消挂载
[root@centos6 ~]# umount /dev/vg0/cx
检查文件系统完整性，这一步必须否则系统不让缩
[root@centos6 ~]# e2fsck -f /dev/vg0/cx

e2fsck 1.41.12 (17-May-2010)
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/vg0/cx: 11/1302528 files (0.0% non-contiguous), 121551/5181440 blocks

缩减文件系统到15G
[root@centos6 ~]# resize2fs /dev/vg0/cx 15G

resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/vg0/cx to 3932160 (4k) blocks.
The filesystem on /dev/vg0/cx is now 3932160 blocks long.

缩减逻辑卷到15G，注意这里缩减的大小与文件系统大小一致
[root@centos6 ~]# lvreduce -L 15G /dev/vg0/cx

 WARNING: Reducing active logical volume to 15.00 GiB.
 THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce vg0/cx? [y/n]: y  提醒用户缩减空间可能会损坏数据
 Size of logical volume vg0/cx changed from 19.77 GiB (2024 extents) to 15.00 GiB (1536 extents).
 Logical volume cx successfully resized.

缩减逻辑卷成

创建逻辑卷快照

[root@centos6 ~]# mount -a 挂载文件系统
[root@centos6 ~]# mount

/dev/sda2 on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0")
/dev/sda1 on /boot type ext4 (rw)
/dev/sda6 on /home type ext4 (rw,usrquota)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
/dev/mapper/vg0-cx on /cx type ext4 (rw)

拷贝数据

[root@centos6 ~]# cp /etc/passwd /cx/
[root@centos6 ~]# ls /cx/

lost+found  passwd

创建快照
[root@centos6 ~]# lvcreate -L 1G -s -n cx-date -p r /dev/vg0/cx

  Rounding up size to full physical extent 1.01 GiB
  Logical volume "cx-date" created.

[root@centos6 ~]# mkdir ll
[root@centos6 ~]# mount /dev/vg0/cx-date ll

mount: block device /dev/mapper/vg0-cx--date is write-protected, mounting read-only  挂载快照

[root@centos6 ~]# ls l 查看快照

lost+found  passwd

[root@centos6 ~]# rm -rf /cx/passwd 删除源文件的部分数据
取消逻辑卷与快照的挂载
[root@centos6 ~]# umount /cx/
[root@centos6 ~]# umount ll/
恢复快照注意恢复快照会被删除

[root@centos6 ~]# lvconvert --merge /dev/vg0/cx-date

Merging of volume cx-date started.
cx: Merged: 100.0%
Merge of snapshot into logical volume cx has finished.
Logical volume "cx-date" successfully removed

快照被删除
[root@centos6 ~]# lvdisplay

  --- Logical volume ---
  LV Path                /dev/vg0/cx
  LV Name                cx
  VG Name                vg0
  LV UUID                YqujVe-SSvL-BDFZ-TuPu-YMTg-lXTe-DnlubY
  LV Write Access        read/write
  LV Creation host, time centos6.chenxi.com, 2017-06-24 08:52:01 +0800
  LV Status              available
  # open                 0
  LV Size                15.00 GiB
  Current LE             1536
  Segments               2
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0

查看是否成功恢复

[root@centos6 ~]# mount -a
[root@centos6 ~]# cat /cx/passwd

root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin......

迁移LVM到其他主机，先取消挂载

迁移前改个名字如果目标主机没有重复名字的卷组就不用更改
vgrename 原名新名字
lvrename 原名新名字改逻辑卷的名字
umount /cx/取消挂载
pvmove /dev/sdc1 迁移PE空间，迁移前应先查看卷组PE空间是否够sdc1 PE空间使用，如果不够应先扩展卷组空间
vgchange -an vg0 禁用卷组
vgexport vg0 导出卷组
拔出对应的硬盘拔出
在目标计算机上
在新系统中安装旧硬盘，并vgimport vg0.
vgchange –ay vg0 启用卷组
mount 挂载