如何在CentOS8上安装和配置Postfix邮件服务器的方法示例_运维_开发者

一、简介 LVM是 Logical Volume Manager（逻辑卷管理）的简写，它是Linux环境下对磁盘分区进行管理的一种机制，它由Heinz Mauelshagen在Linux 2.4内核上实现，于1998年发布到Linux社区中，它允许你在Linux系统上用简单的命令行管理一个完整的逻辑卷管理环境。

二、版本 LVM1 最初的LVM与1998年发布，只在Linux内核2.4版本上可用，它提供最基本的逻辑卷管理。 LVM2 LVM-1的更新版本，在Linux内核2.6中才可用，它在标准的LVM-1功能外还提供了额外的功能。查看：（测试机CentOS 6.6 X86_64）

[root@ZhongH100 ~]# rpm -qa | grep lvm

mesa-private-llvm-3.4-3.el6.x86_64

lvm2-libs-2.02.111-2.el6_6.2.x86_64

lvm2-2.02.111-2.el6_6.2.x86_64

[root@ZhongH100 ~]# cat /etc/centos-release

CentOS release 6.6 (Final)

[root@ZhongH100 ~]# uname -a

Linux ZhongH100.wxjr.com.cn 2.6.32-504.16.2.el6.centos.plus.x86_64 #1 SMP Wed Apr 22 00:59:31 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

[root@ZhongH100 ~]# getconf LONG_BIT

64

三、LVM 模块 Physical volume (PV)、Volume group (VG)、Logical volume(LV)、 Physical extent (PE)，下面我们用一个简单的图来说明下物理卷、卷组、逻辑卷他们之间的关系(此图只是个人理解，仅供参考) LVM 详解

简而言之：逻辑卷的创建，就是将多块硬盘创建物理卷，而将这些物理卷以逻辑的形式总成一个容器，然后从这个容器里面创建大小不同的分区文件，而这个容器就是所谓的逻辑卷，而从这个容器里创建大小不同的分区文件，这个分区文件就叫做逻辑卷。嘿嘿，你懂了吗？ ^_^ ……

四、具体操作 1. 分区（本实验环境使用的是一块新磁盘/dev/sdb）

[root@ZhongH100 ~]# fdisk -l /dev/sd[a-z]

Disk /dev/sda: 64.4 GB, 64424509440 bytes

255 heads, 63 sectors/track, 7832 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: 0x0006c656

Device Boot Start End Blocks Id System

/dev/sda1 * 1 64 512000 83 Linux

Partition 1 does not end on cylinder boundary.

/dev/sda2 64 6591 52428800 8e Linux LVM

Disk /dev/sdb: 64.4 GB, 64424509440 bytes

255 heads, 63 sectors/track, 7832 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: 0x00000000

[root@ZhongH100 ~]#

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[root@ZhongH100 ~]# fdisk /dev/sdb #试用fdisk命令来管理磁盘分区

Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel

Building a new DOS disklabel with disk identifier 0xfb1f25cf.

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 #输入p来打印当前磁盘上的分区

Disk /dev/sdb: 64.4 GB, 64424509440 bytes

255 heads, 63 sectors/track, 7832 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: 0xfb1f25cf

Device Boot Start End Blocks Id System

Command (m for help): n #输入n 新建分区

Command action

e extended

p primary partition (1-4)

p #输入p 选择分区类型为主分区

Partition number (1-4): 1 #输入1 选择为第一个主分区

First cylinder (1-7832, default 1): #直接回车选择分区起始块为1

Using default value 1

Last cylinder, +cylinders or +size{K,M,G} (1-7832, default 7832): +10G #输入+10G 为新分区大小为10G

Command (m for help): n #输入n 在当前磁盘上再次新建一个分区

Command action

e extended

p primary partition (1-4)

p #输入p 选择分区类型为主分区

Partition number (1-4): 2 #输入2 选择为第二个主分区

First cylinder (1307-7832, default 1307): #直接回车选择分区起始块为1307

Using default value 1307

Last cylinder, +cylinders or +size{K,M,G} (1307-7832, default 7832): +10G #输入+10G 为新分区大小为10G

Command (m for help): n #输入n 在当前磁盘上再次新建一个分区

Command action

e extended

p primary partition (1-4)

p #输入p 选择分区类型为主分区

Partition number (1-4): 3 #输入3 选择为第三个主分区

First cylinder (2613-7832, default 2613): #直接回车选择分区起始块为2613

Using default value 2613

Last cylinder, +cylinders or +size{K,M,G} (2613-7832, default 7832): +10G #输入+10G 为新分区大小为10G

Command (m for help): p #输入p来打印当前磁盘上的分区

Disk /dev/sdb: 64.4 GB, 64424509440 bytes

255 heads, 63 sectors/track, 7832 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: 0xfb1f25cf

Device Boot Start End Blocks Id System

/dev/sdb1 1 1306 10490413+ 83 Linux

/dev/sdb2 1307 2612 10490445 83 Linux

/dev/sdb3 2613 3918 10490445 83 Linux

Command (m for help): t #输入t 来改变分区类型

Partition number (1-4): 1 #输入1 来选择改变分区类型的分区号为1

Hex code (type L to list codes): 8e #输入8e 改变分区类型为LVM

Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): t #输入t 来改变分区类型

Partition number (1-4): 2 #输入2 来选择改变分区类型的分区号为2

Hex code (type L to list codes): 8e #输入8e 改变分区类型为LVM

Changed system type of partition 2 to 8e (Linux LVM)

Command (m for help): t #输入t 来改变分区类型

Partition number (1-4): 3 #输入3 来选择改变分区类型的分区号为3

Hex code (type L to list codes): 8e #输入8e 改变分区类型为LVM

Changed system type of partition 3 to 8e (Linux LVM)

Command (m for help): p #输入p来打印当前磁盘上的分区

Disk /dev/sdb: 64.4 GB, 64424509440 bytes

255 heads, 63 sectors/track, 7832 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: 0xfb1f25cf

Device Boot Start End Blocks Id System

/dev/sdb1 1 1306 10490413+ 8e Linux LVM

/dev/sdb2 1307 2612 10490445 8e Linux LVM

/dev/sdb3 2613 3918 10490445 8e Linux LVM

Command (m for help): w

The partition table has been altered!

Calling ioctl() to re-read partition table.

Syncing disks.

[root@ZhongH100 ~]#

新分区完毕后我们需要让内核重新载入,如果执行一次不能载入所有分区那么就多执行几次，直至全部能识别到，我们的sdb上有3个分区，下面的命令已经显示全部识别了

[root@ZhongH100 ~]# partx -a /dev/sdb

BLKPG: Device or resource busy

error adding partition 1

BLKPG: Device or resource busy

error adding partition 2

BLKPG: Device or resource busy

error adding partition 3

2. 将物理分区与硬盘创建为物理卷(pvcreate)

[root@ZhongH100 ~]# pvcreate /dev/sdb1 /dev/sdb2 /dev/sdb3 #这是正常的命令写法也可以使用下面那种扩展写法^C

[root@ZhongH100 ~]# pvcreate /dev/sdb{1,2,3}

Physical volume "/dev/sdb1" successfully created

Physical volume "/dev/sdb2" successfully created

Physical volume "/dev/sdb3" successfully created

[root@ZhongH100 ~]

# pvs                                          #使用pvs来查看当前系统上所有的pv

PV VG Fmt Attr PSize PFree

/dev/sdb1 lvm2 --- 10.00g 10.00g

/dev/sdb2 lvm2 --- 10.00g 10.00g

/dev/sdb3 lvm2 --- 10.00g 10.00g

[root@ZhongH100 ~]#

3. 将物理卷(pv)创建为卷组(vgcreate)，名为VGtest

[root@ZhongH100 ~]# vgcreate VGtest /dev/sdb{1,2,3}

Volume group "VGtest" successfully created

[root@ZhongH100 ~]# vgs

VG #PV #LV #SN Attr VSize VFree

VGtest 3 0 0 wz--n- 30.00g 30.00g

[root@ZhongH100 ~]# vgdisplay

--- Volume group ---

VG Name VGtest #卷组名是VGtest

System ID

Format lvm2

Metadata Areas 3

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 3

Act PV 3

VG Size 30.00 GiB #新的VG大小是30G 3个10G分区组成的

PE Size 4.00 MiB #物理盘的基本单位：默认4MB

Total PE 7680

Alloc PE / Size 0 / 0

Free PE / Size 7680 / 30.00 GiB

VG UUID W8fYiw-Zh46-53lr-qWuf-hqLR-Rqla-x1mFQH

[root@ZhongH100 ~]#

4. 在卷组里创建逻辑卷并格式化、挂载使用

[root@ZhongH100 ~]# lvcreate -L 2G -n LVtest1 VGtest #在名为VGtest的VG上创建一个名为LVtest1 大小为2G的逻辑卷

Logical volume "LVtest1" created

[root@ZhongH100 ~]# lvs #查看系统上的LV逻辑卷

LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert

LVtest1 VGtest -wi-a----- 2.00g

[root@ZhongH100 ~]# mke2fs -t ext4 /dev/VGtest/LVtest1 #格式化新建的LVtest1逻辑卷为ext4格式

mke2fs 1.41.12 (17-May-2010)

文件系统标签=

操作系统:Linux

块大小=4096 (log=2)

分块大小=4096 (log=2)

Stride=0 blocks, Stripe width=0 blocks

131072 inodes, 524288 blocks

26214 blocks (5.00%) reserved for the super user

第一个数据块=0

Maximum filesystem blocks=536870912

16 block groups

32768 blocks per group, 32768 fragments per group

8192 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376, 294912

正在写入inode表: 完成

Creating journal (16384 blocks): 完成

Writing superblocks and filesystem accounting information: 完成

This filesystem will be automatically checked every 25 mounts or

180 days, whichever comes first. Use tune2fs -c or -i to override.

[root@ZhongH100 ~]# mkdir /LVtest1 #创建一个LVtest1的目录

[root@ZhongH100 ~]# mount /dev/VGtest/LVtest1 /LVtest1 #将/dev/VGtest/LVtest1这个逻辑卷挂载到 /LVtest1目录上

[root@ZhongH100 ~]# mount #查看挂载情况

/dev/mapper/vgzhongH-root on / type ext4 (rw,acl)

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)

/dev/sda1 on /boot type ext4 (rw)

/dev/mapper/vgzhongH-data on /data type ext4 (rw,acl)

none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)

/dev/mapper/VGtest-LVtest1 on /LVtest1 type ext4 (rw) #挂载成功分区格式是ext4 可读写

[root@ZhongH100 ~]# df -hP #查看系统上的分区情况

Filesystem Size Used Avail Use% Mounted on

/dev/mapper/vgzhongH-root 30G 3.3G 25G 12% /

tmpfs 932M 0 932M 0% /dev/shm

/dev/sda1 477M 34M 418M 8% /boot

/dev/mapper/vgzhongH-data 4.8G 10M 4.6G 1% /data

/dev/mapper/VGtest-LVtest1 2.0G 3.0M 1.9G 1% /LVtest1 #LVtest1逻辑卷分区正常

[root@ZhongH100 ~]#

5. 发现卷组pv空间不够，我们需要扩大卷组空间
 现在系统上新增了一块20G的硬盘/dev/sdc

[root@ZhongH100 ~]# fdisk -l /dev/sd[a-z]

Disk /dev/sda: 64.4 GB, 64424509440 bytes

255 heads, 63 sectors/track, 7832 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: 0x0006c656

Device Boot Start End Blocks Id System

/dev/sda1 * 1 64 512000 83 Linux

Partition 1 does not end on cylinder boundary.

/dev/sda2 64 6591 52428800 8e Linux LVM

Disk /dev/sdb: 64.4 GB, 64424509440 bytes

255 heads, 63 sectors/track, 7832 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: 0xfb1f25cf

Device Boot Start End Blocks Id System

/dev/sdb1 1 1306 10490413+ 8e Linux LVM

/dev/sdb2 1307 2612 10490445 8e Linux LVM

/dev/sdb3 2613 3918 10490445 8e Linux LVM

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: 0x00000000

[root@ZhongH100 ~]# pvcreate /dev/sdc #将新硬盘/sdc加入物理卷上

Physical volume "/dev/sdc" successfully created

[root@ZhongH100 ~]# pvs #查看物理卷

PV VG Fmt Attr PSize PFree

/dev/sdb1 VGtest lvm2 a-- 10.00g 8.00g

/dev/sdb2 VGtest lvm2 a-- 10.00g 10.00g

/dev/sdb3 VGtest lvm2 a-- 10.00g 10.00g

/dev/sdc lvm2 --- 20.00g 20.00g

[root@ZhongH100 ~]# vgextend VGtest /dev/sdc #扩展卷组

Volume group "VGtest" successfully extended

[root@ZhongH100 ~]# vgs #查看卷组

VG #PV #LV #SN Attr VSize VFree

VGtest 4 1 0 wz--n- 50.00g 48.00g #从大小可以看出我们已经扩容成功

6. 扩展逻辑卷 (支持在线扩展)
 在线将/dev/VGtest/LVtest1 扩展到4G，并且要求数据可以正常访问

[root@ZhongH100 ~]# cd /LVtest1/

[root@ZhongH100 LVtest1]# echo "this is a test for LVM" > lvtest #穿件个lvtest的文件并写入内容

[root@ZhongH100 LVtest1]# cat lvtest

this is a test for LVM

[root@ZhongH100 LVtest1]# lvs

LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert

LVtest1 VGtest -wi-ao---- 2.00g

[root@ZhongH100 LVtest1]# lvextend -L +2G /dev/VGtest/LVtest1

Size of logical volume VGtest/LVtest1 changed from 2.00 GiB (512 extents) to 4.00 GiB (1024 extents).

Logical volume LVtest1 successfully resized

[root@ZhongH100 LVtest1]# lvs

LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert

LVtest1 VGtest -wi-ao---- 4.00g #逻辑卷空间已经增加

[root@ZhongH100 LVtest1]# e2fsck -f /dev/VGtest/LVtest1

[root@ZhongH100 LVtest1]# resize2fs -p /dev/VGtest/LVtest1 #通过 resize2fs 将文件系统的容量确实添加

resize2fs 1.41.12 (17-May-2010)

Filesystem at /dev/VGtest/LVtest1 is mounted on /LVtest1; on-line resizing required

old desc_blocks = 1, new_desc_blocks = 1

Performing an on-line resize of /dev/VGtest/LVtest1 to 1048576 (4k) blocks.

The filesystem on /dev/VGtest/LVtest1 is now 1048576 blocks long.

[root@ZhongH100 LVtest1]# cat l

lost+found/ lvtest

[root@ZhongH100 LVtest1]# cat lvtest #文件没有受损

this is a test for LVM

[root@ZhongH100 LVtest1]# df -hP

Filesystem Size Used Avail Use% Mounted on

/dev/mapper/vgzhongH-root 30G 3.3G 25G 12% /

tmpfs 932M 0 932M 0% /dev/shm

/dev/sda1 477M 34M 418M 8% /boot

/dev/mapper/vgzhongH-data 4.8G 10M 4.6G 1% /data

/dev/mapper/VGtest-LVtest1 3.9G 4.0M 3.7G 1% /LVtest1 #挂载的分区空间已经增加

[root@ZhongH100 LVtest1]#

如果是xfs文件系统话上面这种扩容方法就不行了，需要用下面的方法, 参考：https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/xfsgrow.html http://oss.sgi.com/archives/xfs/2001-05/msg03189.html

[root@www ~]# pvs

PV VG Fmt Attr PSize PFree

/dev/xvda2 LBVG lvm2 a-- 14.51g 0

/dev/xvda3 LBVG lvm2 a-- 135.00g 85.01g

[root@www ~]# vgs

VG #PV #LV #SN Attr VSize VFree

LBVG 2 2 0 wz--n- 149.51g 85.01g

[root@www ~]# lvs

LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert

root LBVG -wi-ao---- 62.00g

swap LBVG -wi-ao---- 2.50g

[root@www ~]# lvcreate -L 10G -n data LBVG

Logical volume "data" created.

[root@www ~]# lvs

LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert

data LBVG -wi-a----- 10.00g

root LBVG -wi-ao---- 62.00g

swap LBVG -wi-ao---- 2.50g

[root@www ~]# mkfs.xfs /dev/LBVG/data

meta-data=/dev/LBVG/data isize=512 agcount=4, agsize=655360 blks

= sectsz=512 attr=2, projid32bit=1

= crc=1 finobt=1, sparse=0

data = bsize=4096 blocks=2621440, imaxpct=25

= sunit=0 swidth=0 blks

naming =version 2 bsize=4096 ascii-ci=0 ftype=1

log =internal log bsize=4096 blocks=2560, version=2

= sectsz=512 sunit=0 blks, lazy-count=1

realtime =none extsz=4096 blocks=0, rtextents=0

[root@www ~]# lvextend -L +5G /dev/LBVG/data

Size of logical volume LBVG/data changed from 10.00 GiB (2560 extents) to 15.00 GiB (3840 extents).

Logical volume data successfully resized.

[root@www ~]# lvs

LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert

data LBVG -wi-a----- 15.00g

root LBVG -wi-ao---- 62.00g

swap LBVG -wi-ao---- 2.50g

[root@www ~]# e2fsck -f /dev/LBVG/data

e2fsck 1.42.13 (17-May-2015)

ext2fs_open2: Bad magic number in super-block

e2fsck: 超级块无效, trying backup blocks...

e2fsck: Bad magic number in super-block 当尝试打开 /dev/LBVG/data 时

The 超级块 could not be read or does not describe a valid ext2/ext3/ext4

文件系统. If the 设备 is valid and it really contains an ext2/ext3/ext4

文件系统 (and not swap or ufs or something else), then the 超级块

is corrupt, and you might try running e2fsck with an alternate 超级块:

e2fsck -b 8193 <设备>

or

e2fsck -b 32768 <设备>

[root@www ~]# mkdir /data

[root@www ~]# mount /dev/LBVG/data /data

[root@www ~]# df -hP|grep /data

文件系统容量已用可用已用% 挂载点

/dev/mapper/LBVG-data 10G 33M 10G 1% /data

[root@www ~]# xfs_growfs /dev/LBVG/data

meta-data=/dev/mapper/LBVG-data isize=512 agcount=4, agsize=655360 blks

= sectsz=512 attr=2, projid32bit=1

= crc=1 finobt=1 spinodes=0

data = bsize=4096 blocks=2621440, imaxpct=25

= sunit=0 swidth=0 blks

naming =version 2 bsize=4096 ascii-ci=0 ftype=1

log =internal bsize=4096 blocks=2560, version=2

= sectsz=512 sunit=0 blks, lazy-count=1

realtime =none extsz=4096 blocks=0, rtextents=0

data blocks changed from 2621440 to 3932160

[root@www ~]# df -hP|grep /data

文件系统容量已用可用已用% 挂载点

/dev/mapper/LBVG-data 15G 33M 15G 1% /data

[root@www ~]#

7. 缩减逻辑卷
 查看逻辑卷使用空间状况 不能在线缩减，得先卸载 切记
 确保缩减后的空间大小依然能存储原有的所有数据
 在缩减之前应该先强行检查文件，以确保文件系统处于一至性状态

[root@ZhongH100 ~]# umount /dev/VGtest/LVtest1 #卸载/dev/VGtest/LVtest1

[root@ZhongH100 ~]# e2fsck -f /dev/VGtest/LVtest1 #强制检查文件系统

e2fsck 1.41.12 (17-May-2010)

第一步: 检查inode,块,和大小

第二步: 检查目录结构

第3步: 检查目录连接性

Pass 4: Checking reference counts

第5步: 检查簇概要信息

/dev/VGtest/LVtest1: 12/262144 files (0.0% non-contiguous), 33871/1048576 blocks

[root@ZhongH100 ~]# resize2fs /dev/VGtest/LVtest1 1G #缩减逻辑大小到1G

resize2fs 1.41.12 (17-May-2010)

Resizing the filesystem on /dev/VGtest/LVtest1 to 262144 (4k) blocks.

The filesystem on /dev/VGtest/LVtest1 is now 262144 blocks long.

[root@ZhongH100 ~]# lvreduce -L 1G /dev/VGtest/LVtest1

WARNING: Reducing active logical volume to 1.00 GiB

THIS MAY DESTROY YOUR DATA (filesystem etc.)

Do you really want to reduce LVtest1? [y/n]: y #输入y 同意裁剪

Size of logical volume VGtest/LVtest1 changed from 4.00 GiB (1024 extents) to 1.00 GiB (256 extents).

Logical volume LVtest1 successfully resized

[root@ZhongH100 ~]# lvs #查看逻辑卷

LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert

LVtest1 VGtest -wi-a----- 1.00g

[root@ZhongH100 ~]# mount /dev/VGtest/LVtest1 /LVtest1/ #挂载逻辑卷/dev/VGtest/LVtest1

[root@ZhongH100 ~]# df -hP #查看系统分区详情

Filesystem Size Used Avail Use% Mounted on

/dev/mapper/vgzhongH-root 30G 3.3G 25G 12% /

tmpfs 932M 0 932M 0% /dev/shm

/dev/sda1 477M 34M 418M 8% /boot

/dev/mapper/vgzhongH-data 4.8G 10M 4.6G 1% /data

/dev/mapper/VGtest-LVtest1 944M 2.6M 891M 1% /LVtest1 #已经缩减成功

[root@ZhongH100 ~]# cat /LVtest1/lvtest #查看缩减前文件是否受损

this is a test for LVM

[root@ZhongH100 ~]#

8. 缩减磁盘空间
 发现物理磁盘空间使用不足，将其中一块硬盘或分区拿掉
 pvmove /dev/sdb1 #将/dev/sdb1上存储的数据移到其它物理卷中
 vgreduce VGtest /dev/sdb1 #将/dev/sdb1从VGtest卷组中移除
 pvremove /dev/sdb1 #将/dev/sdb1从物理卷上移除

[root@ZhongH100 ~]# pvs

PV VG Fmt Attr PSize PFree

/dev/sdb1 VGtest lvm2 a-- 10.00g 9.00g

/dev/sdb2 VGtest lvm2 a-- 10.00g 10.00g

/dev/sdb3 VGtest lvm2 a-- 10.00g 10.00g

/dev/sdc VGtest lvm2 a-- 20.00g 20.00g

[root@ZhongH100 ~]# pvmove /dev/sdb1

/dev/sdb1: Moved: 2.3%

/dev/sdb1: Moved: 86.3%

/dev/sdb1: Moved: 100.0%

[root@ZhongH100 ~]# vgreduce VGtest /dev/sdb1

Removed "/dev/sdb1" from volume group "VGtest"

[root@ZhongH100 ~]# pvremove /dev/sdb1

Labels on physical volume "/dev/sdb1" successfully wiped

[root@ZhongH100 ~]# pvs

PV VG Fmt Attr PSize PFree

/dev/sdb2 VGtest lvm2 a-- 10.00g 9.00g

/dev/sdb3 VGtest lvm2 a-- 10.00g 10.00g

/dev/sdc VGtest lvm2 a-- 20.00g 20.00g

[root@ZhongH100 ~]#

9. 实现快照，进行备份还原
 在/mnt/lvm目录上，我们将原始的目录文件进行快照，然后将/LVtets1目录中的内容清空，并进行还原

[root@ZhongH100 ~]# cat /LVtest1/lvtest

this is a test for LVM

[root@ZhongH100 ~]# lvcreate -L 30M -n backup -s -p r /dev/VGtest/LVtest1

Rounding up size to full physical extent 32.00 MiB

Logical volume "backup" created

[root@ZhongH100 ~]# mkdir /tmp/backup/

[root@ZhongH100 ~]# mount /dev/VGtest/backup /tmp/backup/

mount: block device /dev/mapper/VGtest-backup is write-protected, mounting read-only

[root@ZhongH100 ~]# cat /tmp/backup/lvtest

this is a test for LVM

[root@ZhongH100 ~]# rm -rf /LVtest1/*

You are going to execute "/bin/rm -rf /LVtest1/lost+found /LVtest1/lvtest",please confirm (yes or no):yes

[root@ZhongH100 ~]# cd /LVtest1/

[root@ZhongH100 LVtest1]# ls -l

总用量 0

[root@ZhongH100 LVtest1]# tar xf /tmp/sandy.tar.bz2

[root@ZhongH100 LVtest1]# ls -l

总用量 8

drwx------ 2 root root 4096 5月 21 23:33 lost+found

-rw-r--r-- 1 root root 23 5月 21 23:53 lvtest

[root@ZhongH100 LVtest1]# cat lvtest

this is a test for LVM

[root@ZhongH100 LVtest1]# df -hP

Filesystem Size Used Avail Use% Mounted on

/dev/mapper/vgzhongH-root 30G 3.3G 25G 12% /

tmpfs 932M 0 932M 0% /dev/shm

/dev/sda1 477M 34M 418M 8% /boot

/dev/mapper/vgzhongH-data 4.8G 10M 4.6G 1% /data

/dev/mapper/VGtest-LVtest1 944M 2.5M 891M 1% /LVtest1

/dev/mapper/VGtest-backup 944M 2.6M 891M 1% /tmp/backup

[root@ZhongH100 LVtest1]#

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