LVM的创建、扩容和缩减

文章目录

[隐藏]

• 一、创建LVM系统
  • 1. 硬盘分区
  • 2. 创建物理卷
  • 3. 创建卷组
  • 4. 创建逻辑卷
  • 5. 挂载文件系统
• 二、扩展逻辑卷
• 三、缩减逻辑卷
• 四、从卷组移除物理卷
• 五、常用命令

一、创建LVM系统

1. 硬盘分区

首先我们需要为我们的虚拟机添加一个虚拟硬盘，过程略。

查看硬盘设备：

[[email protected] ~]# fdisk -l  ...  Disk /dev/sdc: 10.7 GB, 10737418240 bytes  255 heads, 63 sectors/track, 1305 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: 0xa2c6e480       Device Boot      Start         End      Blocks   Id  System  ...  

如上/dev/sdc是我们新添加的硬盘设备。
我们需要在/dev/sdc基础上创建分区并修改分区系统类型为8e：

[[email protected] ~]# fdisk /dev/sdc    WARNING: DOS-compatible mode is deprecated. It is strongly recommended to           switch off the mode (command 'c') and change display units to           sectors (command 'u').    Command (m for help): n                                   # 创建新分区  Command action     e   extended                                                    # 扩展分区     p   primary partition (1-4)                                # 主分区  p  Partition number (1-4): 1                                   # 分区号  First cylinder (1-1305, default 1):                     # 默认从第一个柱面开始划分  Using default value 1  Last cylinder, +cylinders or +size{K,M,G} (1-1305, default 1305): +5G   # 分区大小    Command (m for help): n  Command action     e   extended     p   primary partition (1-4)  p  Partition number (1-4): 2  First cylinder (655-1305, default 655):  Using default value 655  Last cylinder, +cylinders or +size{K,M,G} (655-1305, default 1305): +3G    Command (m for help): n  Command action     e   extended     p   primary partition (1-4)  p  Partition number (1-4): 3  First cylinder (1048-1305, default 1048):  Using default value 1048  Last cylinder, +cylinders or +size{K,M,G} (1048-1305, default 1305):  Using default value 1305    Command (m for help): t                                    # 修改分区系统类型  Partition number (1-4): 1                                    # 选择要修改的分区号  Hex code (type L to list codes): 8e                    #  修改为LVM分区类型，可使用'L'查看所有可使用类型  Changed system type of partition 1 to 8e (Linux LVM)    Command (m for help): t  Partition number (1-4): 2  Hex code (type L to list codes): 8e  Changed system type of partition 2 to 8e (Linux LVM)    Command (m for help): t  Partition number (1-4): 3  Hex code (type L to list codes): 8e  Changed system type of partition 3 to 8e (Linux LVM)    Command (m for help): p                                   # 查看分区情况    Disk /dev/sdc: 10.7 GB, 10737418240 bytes  255 heads, 63 sectors/track, 1305 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: 0xa2c6e480       Device Boot      Start         End      Blocks   Id  System  /dev/sdc1               1         654     5253223+  8e  Linux LVM  /dev/sdc2             655        1047     3156772+  8e  Linux LVM  /dev/sdc3            1048        1305     2072385   8e  Linux LVM    Command (m for help): w                                   # 保存分区表并退出  The partition table has been altered!    Calling ioctl() to re-read partition table.  Syncing disks.  [[email protected] ~]#  

2. 创建物理卷

创建物理卷的命令为pvcreate，利用该命令将希望添加到卷组的所有分区或者硬盘创建为物理卷。

[[email protected] ~]# pvcreate /dev/sdc{1,2}             # 将/dev/sdc1和2创建为物理卷    Physical volume "/dev/sdc1" successfully created    Physical volume "/dev/sdc2" successfully created  [[email protected] ~]# pvs                                           # 查看物理卷信息    PV         VG     Fmt  Attr PSize  PFree    /dev/sdc1         lvm2 ----  5.01g    5.01g    /dev/sdc2         lvm2 ----  3.01g    3.01g  [[email protected] ~]# pvdisplay                                 # 查看物理卷详细信息   ...    "/dev/sdc1" is a new physical volume of "5.01 GiB"    --- NEW Physical volume ---    PV Name               /dev/sdc1    VG Name    PV Size               5.01 GiB    Allocatable           NO    PE Size               0    Total PE              0    Free PE               0    Allocated PE          0    PV UUID               jKHeSG-XYna-zFYi-9Kd9-bWRM-f1zY-Qs7FZZ      "/dev/sdc2" is a new physical volume of "3.01 GiB"    --- NEW Physical volume ---    PV Name               /dev/sdc2    VG Name    PV Size               3.01 GiB    Allocatable           NO    PE Size               0    Total PE              0    Free PE               0    Allocated PE          0    PV UUID               WcKTKi-av0e-so5s-QVXB-yf7G-Tynz-9TQDJb    [[email protected] ~]#  

3. 创建卷组

创建卷组的命令为vgcreate，将使用pvcreate建立的物理卷创建为一个完整的卷组。

[[email protected] ~]# vgcreate myvg /dev/sdc{1,2}     # 创建卷组    Volume group "myvg" successfully created  [[email protected] ~]# vgs                                            # 查看卷组信息    VG     #PV #LV #SN Attr   VSize  VFree    myvg     2   0   0 wz--n-  8.02g    8.02g  [[email protected] ~]# vgdisplay myvg                         # 查看卷组详细信息    --- 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               8.02 GiB                                     # 卷组的大小，由上面两个分区决定    PE Size               4.00 MiB                                     # PE大小可以在vgcreate命令中使用'-s'指定，默认为4M    Total PE              2052    Alloc PE / Size       0 / 0    Free  PE / Size       2052 / 8.02 GiB    VG UUID               4aIItM-FyPx-GJ47-1A70-b8W4-EwfH-beFZrZ    [[email protected] ~]# pvdisplay                                   # 再次查看物理卷，跟上一次查看有所区别    --- Physical volume ---    PV Name               /dev/sdc1    VG Name               myvg    PV Size               5.01 GiB / not usable 2.10 MiB    Allocatable           yes    PE Size               4.00 MiB    Total PE              1282    Free PE               1282    Allocated PE          0    PV UUID               jKHeSG-XYna-zFYi-9Kd9-bWRM-f1zY-Qs7FZZ      --- Physical volume ---    PV Name               /dev/sdc2    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               WcKTKi-av0e-so5s-QVXB-yf7G-Tynz-9TQDJb    [[email protected] ~]#  

4. 创建逻辑卷

创建逻辑卷的命令为lvcreate

[[email protected] ~]# lvcreate -L 6G -n mylv myvg    Logical volume "mylv" created.  [[email protected] ~]#  

使用方法：

lvcreate -L #G -n LV_NAME VG_NAME  

参数解释：

• -L: 指定逻辑卷大小，不可超过卷组大小
• -n: 指定逻辑卷名称
   

5. 挂载文件系统

至此我们的逻辑卷就已创建完成，接下来我们就需要格式化分区并挂载使用啦。

[[email protected] ~]# mkfs.ext4 /dev/myvg/mylv      # 格式化分区  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 /dev/sdc3" successfully created  [[email protected] ~]# vgextend myvg /dev/sdc3      # 添加物理卷到卷组    Volume group "myvg" successfully extended  [[email protected] ~]# pvs                                         # 查看物理卷信息    PV         VG     Fmt  Attr PSize  PFree    /dev/sdb   datavg lvm2 a--u 20.00g 1020.00m    /dev/sdc1  myvg   lvm2 a--u  5.01g       0    /dev/sdc2  myvg   lvm2 a--u  3.01g    2.02g    /dev/sdc3  myvg   lvm2 a--u  1.97g    1.97g        # /dev/sdc3已加入myvg卷组  [[email protected] ~]# vgs                                        # 卷组信息    VG     #PV #LV #SN Attr   VSize  VFree    datavg   1   1   0 wz--n- 20.00g 1020.00m    myvg     3   1   0 wz--n-  9.99g    3.99g               # 卷组容量比之前扩大  [[email protected] ~]# lvextend -L 9G /dev/myvg/mylv    # 扩展逻辑卷容量到9G    Size of logical volume myvg/mylv changed from 6.00 GiB (1536 extents) to 9.00 GiB (2304 extents).    Logical volume mylv successfully resized.  [[email protected] ~]# lvs    LV     VG     Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert    nsas01 datavg -wi-ao---- 19.00g    mylv   myvg   -wi-a-----  9.00g                              # 逻辑卷容量成功扩展到9G  [[email protected] ~]# df -h  Filesystem            Size  Used Avail Use% Mounted on  ...  /dev/mapper/myvg-mylv                        5.8G   12M  5.5G   1% /mnt             # 但是分区空间还是初始大小  [[email protected] ~]# resize2fs -p /dev/myvg/mylv  # 改变分区大小为逻辑卷大小  resize2fs 1.41.12 (17-May-2010)  Filesystem at /dev/myvg/mylv is mounted on /mnt; on-line resizing required  old desc_blocks = 1, new_desc_blocks = 1  Performing an on-line resize of /dev/myvg/mylv to 2359296 (4k) blocks.  The filesystem on /dev/myvg/mylv is now 2359296 blocks long.    [[email protected] ~]# df -h  Filesystem            Size  Used Avail Use% Mounted on  ...  /dev/mapper/myvg-mylv                        8.8G   14M  8.3G   1% /mnt           # 分区大小成功扩展到9G  [[email protected] ~]#  

三、缩减逻辑卷

注意事项：

1. 缩减前需要先卸载挂载；
2. 要确保缩减后的空间依然能够存储原有的所有数据；
3. 缩减之前需要先强行检查文件，确保文件系统处于一致性状态。

[[email protected] ~]# umount /dev/myvg/mylv             # 卸载挂载分区  [[email protected] ~]# e2fsck -f /dev/myvg/mylv           # 强行检查文件系统  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/myvg/mylv: 11/589824 files (0.0% non-contiguous), 73247/2359296 blocks  [[email protected] ~]# resize2fs /dev/myvg/mylv 8G    # 改变分区大小  resize2fs 1.41.12 (17-May-2010)  Resizing the filesystem on /dev/myvg/mylv to 2097152 (4k) blocks.  The filesystem on /dev/myvg/mylv is now 2097152 blocks long.    [[email protected] ~]# lvreduce -L 8G /dev/myvg/mylv  # 改变逻辑卷大小    WARNING: Reducing active logical volume to 8.00 GiB.    THIS MAY DESTROY YOUR DATA (filesystem etc.)  Do you really want to reduce myvg/mylv? [y/n]: y    Size of logical volume myvg/mylv changed from 9.00 GiB (2304 extents) to 8.00 GiB (2048 extents).    Logical volume mylv successfully resized.  [[email protected] ~]# mount /dev/myvg/mylv /mnt/  [[email protected] ~]# df -h  ...  /dev/mapper/myvg-mylv                        7.8G   14M  7.4G   1% /mnt                 # 分区大小成功缩减为8G  [[email protected] ~]#  

四、从卷组移除物理卷

[[email protected] ~]# lvs    LV     VG     Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert    nsas01 datavg -wi-ao---- 19.00g    mylv   myvg   -wi-ao----  8.00g  [[email protected] ~]# vgs    VG     #PV #LV #SN Attr   VSize  VFree    datavg   1   1   0 wz--n- 20.00g 1020.00m    myvg     3   1   0 wz--n-  9.99g    1.99g  [[email protected] ~]# pvs    PV         VG     Fmt  Attr PSize  PFree    /dev/sdc1  myvg   lvm2 a--u  5.01g       0    /dev/sdc2  myvg   lvm2 a--u  3.01g   16.00m    /dev/sdc3  myvg   lvm2 a--u  1.97g    1.97g  [[email protected] ~]#  

我们的目前状态：

• 挂载分区空间为8G；
• 逻辑卷(LV)空间大小为8G；
• 卷组(VG)空间大小为9.99G，剩余1.99G；
• 物理卷/dev/sdc3空间未使用。

那么我们是否可以将/dev/sdc3从卷组中移除出来呢？

[[email protected] ~]# pvmove /dev/sdc3              # 移动/dev/sdc3中数据到其他物理卷    No data to move for myvg  [[email protected] ~]# vgreduce myvg /dev/sdc3  # 从myvg卷组中移除/dev/sdc3物理卷    Removed "/dev/sdc3" from volume group "myvg"  [[email protected] ~]# pvremove /dev/sdc3           # 移除物理卷/dev/sdc3    Labels on physical volume "/dev/sdc3" successfully wiped  [[email protected] ~]# pvs                                      # /dev/sdc3成功从卷组myvg中移除    PV         VG     Fmt  Attr PSize  PFree    /dev/sdb   datavg lvm2 a--u 20.00g 1020.00m    /dev/sdc1  myvg   lvm2 a--u  5.01g       0    /dev/sdc2  myvg   lvm2 a--u  3.01g   16.00m  [[email protected] ~]# vgs                                      # 卷组空间大小缩减了/dev/sdc3空间大小    VG     #PV #LV #SN Attr   VSize  VFree    datavg   1   1   0 wz--n- 20.00g 1020.00m    myvg     2   1   0 wz--n-  8.02g   16.00m  [[email protected] ~]#  

五、常用命令

• 物理卷管理(PV)

pvcreate、pvdisplay、pvmove、pvremove、pvs  

• 卷组管理(VG)

vgcreate、vgdisplay、vgextend、vgreduce、vgremove、vgrename、vgs  

• 逻辑卷管理(LV)

lvcreate、lvdisplay、lvextend、lvreduce、lvremove、lvrename、lvs  

原文出处：51cto -> http://blog.51cto.com/10074802/2131204