LVM磁盘管理

最新推荐文章于 2022-09-09 16:51:37 发布

转载最新推荐文章于 2022-09-09 16:51:37 发布 · 195 阅读

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#运维 #操作系统

LVM基本术语

前面谈到，LVM是在磁盘分区和文件系统之间添加的一个逻辑层，来为文件系统屏蔽下层磁盘分区布局，提供一个抽象的盘卷，在盘卷上建立文件系统。首先我们讨论以下几个LVM术语：

物理存储介质（The physical media）：这里指系统的存储设备：硬盘，如：/dev/hda1、/dev/sda等等，是存储系统最低层的存储单元。

物理卷（physical volume）：物理卷就是指硬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）：LVM卷组类似于非LVM系统中的物理硬盘，其由物理卷组成。可以在卷组上创建一个或多个“LVM分区”（逻辑卷），LVM卷组由一个或多个物理卷组成。

逻辑卷（logical volume）：LVM的逻辑卷类似于非LVM系统中的硬盘分区，在逻辑卷之上可以建立文件系统(比如/home或者/usr等)。

PE（physical extent）：每一个物理卷被划分为称为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。

LE（logical extent）：逻辑卷也被划分为被称为LE(Logical Extents) 的可被寻址的基本单位。在同一个卷组中，LE的大小和PE是相同的，并且一一对应。

简单来说就是：

PV:是物理的磁盘分区

VG:LVM中的物理的磁盘分区，也就是PV，必须加入VG，可以将VG理解为一个仓库或者是几个大的硬盘。

LV：也就是从VG中划分的逻辑分区

如下图所示PV、VG、LV三者关系：

创建一个大小为300M，分区类型为LVM的sdb1

[root@IHS ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x9d2251e5.
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): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2610, default 1): 
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): +300M

Command (m for help): p

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: 0x9d2251e5

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1          39      313236   83  Linux

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): p

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: 0x9d2251e5

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1          39      313236   8e  Linux LVM

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

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

让内核同步分区信息（此步骤仅在没有找到分区设备的情况下才需要执行，非必要动作。）：

[root@IHS ~]# partprobe

启用LVM并创建lv_data逻辑卷

1.将新建的分区设置为物理卷：

[root@IHS ~]# pvcreate /dev/sdb1
  dev_is_mpath: failed to get device for 8:17
  Physical volume "/dev/sdb1" successfully created

2.将物理卷加入卷组vg_data：

[root@IHS ~]# vgcreate vg_date /dev/sdb1
  Volume group "vg_date" successfully created

3.查看卷组信息

[root@IHS ~]# vgdisplay 
  --- Volume group ---
  VG Name               vg_date
  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               304.00 MiB
  PE Size               4.00 MiB
  Total PE              76
  Alloc PE / Size       0 / 0   
  Free  PE / Size       76 / 304.00 MiB
  VG UUID               LfClWd-y3Oo-pZ0U-Nwmb-6QiA-L0sb-dJgASE
   
[root@IHS ~]# vgs
  VG      #PV #LV #SN Attr   VSize   VFree  
  vg_date   1   0   0 wz--n- 304.00m 304.00m

4.生成150M的逻辑卷lv_data

[root@IHS ~]# lvcreate -L 150M -n lv_data vg_date
  Rounding up size to full physical extent 152.00 MiB
  Logical volume "lv_data" created

5.格式化逻辑卷

[root@IHS ~]# mkfs.ext4 /dev/vg_date/lv_data 
Writing superblocks and filesystem accounting information: done

6.创建挂载目录/data,并将lv_data挂载在该目录。

[root@IHS ~]# mkdir /data 
[root@IHS ~]# mount /dev/vg_date/lv_data /data

7.查看挂载信息

[root@IHS ~]# df -h
Filesystem                   Size  Used Avail Use% Mounted on
/dev/sda3                     89G   20G   66G  23% /
tmpfs                        4.1G   72K  4.1G   1% /dev/shm
/dev/sda1                    194M   34M  151M  19% /boot
/dev/mapper/vg_date-lv_data  148M  5.6M  135M   4% /data

扩容卷组

vgextend vg_wls12c /dev/sdb1

扩容逻辑卷

将逻辑卷lv_data扩大到500M

1.若要对LVM进行调整，一定要先卸载：

[root@IHS /]# umount /data

2.将逻辑卷拓展到250M

[root@IHS ~]# lvextend -L 250M /dev/vg_date/lv_data
  Rounding size to boundary between physical extents: 252.00 MiB
  Extending logical volume lv_data to 252.00 MiB
  Logical volume lv_data successfully resized

3.检查磁盘完整性

[root@IHS ~]# e2fsck -f /dev/vg_date/lv_data 
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/vg_date/lv_data: 12/38912 files (0.0% non-contiguous), 10562/155648 blocks

4.重置磁盘容量

[root@IHS ~]# resize2fs /dev/vg_date/lv_data
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/vg_date/lv_data to 258048 (1k) blocks.
The filesystem on /dev/vg_date/lv_data is now 258048 blocks long.

5.挂载磁盘

[root@IHS ~]# mount /dev/vg_date/lv_data /data

6.查看挂载信息

[root@IHS ~]# df -h
Filesystem                   Size  Used Avail Use% Mounted on
/dev/sda3                     89G   20G   66G  23% /
tmpfs                        4.1G   72K  4.1G   1% /dev/shm
/dev/sda1                    194M   34M  151M  19% /boot
/dev/mapper/vg_date-lv_data  244M  6.1M  226M   3% /data

减小逻辑卷到100M

1.卸载文件系统

[root@IHS ~]# umount /data

2.检查文件系统的完整性

root@IHS ~]# e2fsck -f /dev/vg_date/lv_data 
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/vg_date/lv_data: 12/65536 files (0.0% non-contiguous), 14432/258048 blocks

3.将逻辑卷的减小到100M:

[root@IHS ~]# resize2fs /dev/vg_date/lv_data 100M
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/vg_date/lv_data to 102400 (1k) blocks.
The filesystem on /dev/vg_date/lv_data is now 102400 blocks long.

4.将逻辑卷lv_data减小到100M

[root@IHS ~]# lvreduce -L 100M /dev/vg_date/lv_data 
  WARNING: Reducing active logical volume to 100.00 MiB
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce lv_data? [y/n]: y
  Reducing logical volume lv_data to 100.00 MiB
  Logical volume lv_data successfully resized

5.挂载文件系统，查看逻辑卷大小是否是100M

[root@IHS ~]# mount /dev/vg_date/lv_data /data/
[root@IHS ~]# df -h
Filesystem                   Size  Used Avail Use% Mounted on
/dev/sda3                     89G   20G   66G  23% /
tmpfs                        4.1G   72K  4.1G   1% /dev/shm
/dev/sda1                    194M   34M  151M  19% /boot
/dev/mapper/vg_date-lv_data   97M  5.6M   87M   7% /data

使用逻辑卷快照功能

1.移动一些文件到/data目录下，做测试

[root@IHS ~]# ls /data
2.docx  3.docx  4.docx  5.docx  lost+found

2.查看逻辑卷的使用量

[root@IHS data]# df -h
Filesystem                   Size  Used Avail Use% Mounted on
/dev/mapper/vg_date-lv_data   97M   75M   18M  81% /data

3.创建逻辑卷快照

[root@IHS data]# lvcreate -L 50M -s -n SNAP /dev/vg_date/lv_data 
  Rounding up size to full physical extent 52.00 MiB
  Logical volume "SNAP" created

4.删除/data下的文件，看恢复快照后是否能恢复该时间点的文件

[root@IHS data]# rm -rf  /data/*

5.卸载目录

[root@IHS data]# umount /data
umount: /data: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
出现报错，则执行:
[root@IHS data]# fuser -k /data

重新挂载：

[root@IHS data]# umount /data

6.恢复快照

[root@IHS ~]# lvconvert --merge /dev/vg_date/SNAP 
  Merging of volume SNAP started.
  lv_data: Merged: 100.0%
  Merge of snapshot into logical volume lv_data has finished.
  Logical volume "SNAP" successfully removed

7.挂载文件系统

[root@IHS ~]# mount /dev/vg_date/lv_data /data

8.检验效果，文件是否恢复

[root@IHS ~]# df -h
Filesystem                   Size  Used Avail Use% Mounted on
/dev/sda3                     89G   20G   66G  23% /
tmpfs                        4.1G   72K  4.1G   1% /dev/shm
/dev/sda1                    194M   34M  151M  19% /boot
/dev/mapper/vg_date-lv_data   97M   75M   18M  81% /data
[root@IHS ~]# ls /data
2.docx  3.docx  4.docx  5.docx  lost+found

开机自动挂载

echo "/dev/vg_date/lv_data /data ext4 defaults 0 0" >> /etc/fstab