如何在CentOS8上安装和配置Postfix邮件服务器的方法示例

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。

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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）

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[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

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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？ ^_^ ……

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四、具体操作 1. 分区 （本实验环境使用的是一块新磁盘/dev/sdb）

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[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

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[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)

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[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

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[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

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[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

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[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

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[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

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[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

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[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

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[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

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[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

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[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]#