lvm入门

实例： 
使用lvm存储结构的主机需要扩容，现在我们已经将一个新的硬盘安装上去，将该新的硬盘的空间全部增加到主机上

   20  ls /dev/sd*          #查看新增加的硬盘名，我的为xvdb
   21  ls /dev
   22  fdisk -l
   23  fdisk /dev/xvdb      #对其进行操作（写下来大概是m,n,p,1,t,8e,w）
   24  pvcreate /dev/xvdb1  #增加物理卷
   25  vgdisplay            #查看组，组名为cl
   26  vgextend cl /dev/xvdb1  #扩展/dev/xvdb1到cl组
   27  vgdisplay
   28  lvdisplay               #获取lv路径
   29  lvresize -l +127999 /dev/cl/root  #-l指定大小，因为前面已经vgextend，127999这个值可以从vgdisplay这里获取（Free PE）
   30  df -h
   31  df -Th      #需要注意文件系统格式，如果是xfs格式，使用下一条命令，如果不是则是另一条resize2fs /dev/cl/root
   32  xfs_growfs /dev/cl/root    #xfs_growfs会自动扩展至最大可用值，这条命令只能用于文件系统是xfs的，文件系统可以通过df -Th查看，其他的文件系统就不是用这个命令了
   33  df -h

可能会遇到一个问题，那就是在vgextend时报错，可能是因为磁盘太满了，建议清空部分文件，再次执行扩容

以下为详细过程及讲解

二次整理lvm：

首先，往系统中添加物理磁盘或虚拟磁盘，如果热插没有直接识别，可以尝试以下三条命令（或者是partprobe，不过这条命令我没试过，好像是fdisk之后才用的）

[root@localhost ~]# echo ‘- - -‘> /sys/class/scsi_host/host0/scan 
[root@localhost ~]# echo ‘- - -‘> /sys/class/scsi_host/host1/scan 
[root@localhost ~]# echo ‘- - -‘> /sys/class/scsi_host/host3/scan

首先是确认是否添加磁盘成功

ls /dev/xvd*  (需要根据具体情况，我这个是xen虚拟平台的，如果是vm之类的虚拟软件，新设备名称可能是sd开头的)，有显示则表示成功，或者有ll /dev下面的文件，修改时间为最新的即为新增磁盘设备

接下来就可以开始进行lvm操作了，直接上图看一下吧

先看一下，在原lvm基础上怎么扩展原空间吧

[root@localhost ~]# fdisk /dev/xvdb     #进行fdisk操作，后面是我新增的磁盘
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xde5438c0.
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  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   #n是指新增分区
Command action
   e   extended
   p   primary partition (-)
p　　#这里还需要按p
Partition number (-): 1    #新增分区号
First cylinder (-, default ):    #分区开始位置，回车默认就可以了
Using default value
Last cylinder, +cylinders or +size{K,M,G} (-, default ):  #选择分区大小，可以使用例如+50G然后回车确认，+50G的意思是该分区大小分50G
Using default value 

Command (m for help): t    #设置分区类型
Selected partition 1       #如果有多个分区，这里也有分别选中想操作的分区号
Hex code (type L to list codes): 8e      #我选择的是LVM类型,可以使用L查看全部类型
Changed system type of partition  to 8e (Linux LVM)

Command (m for help): w　　　　#保存这次修改并退出
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# vgextend VolGroup /dev/xvdb1  #将新增的分区加到vg，扩大vg容量，加入vg的好处是在vg中的lv可以动态扩展大小（注意xvdb1，也就是我们刚才选择的分区号，如果是选的2的话，则应是xvdb2）
  Physical volume "/dev/xvdb1" successfully created
  Volume group "VolGroup" successfully extended
[root@localhost ~]# lvextend -L +52G /dev/VolGroup/lv_root   #这里比较烦，我增加的是52G的磁盘，提示空间不够，那就相当于有损耗呗，空间稍微减少个1G就成功了，后面的lv_root可以从lvdisplay中查看
  Insufficient free space:  extents needed, but only  available
[root@localhost ~]# lvextend -L +51G /dev/VolGroup/lv_root　　
  Size of logical volume VolGroup/lv_root changed from 28.31 GiB ( extents) to
79.31 GiB ( extents).  Logical volume lv_root successfully resized
[root@localhost ~]# resize2fs /dev/VolGroup/lv_root    #扩展之后，还需重置lv大小，resize2fs是针对etx4的，xfs是xfs_growfs,不知道为什么，这里不用格式化lv卷。执行之后df -Th应该就能显示增加成功了
resize2fs 1.41. (-May-)
Filesystem at /dev/VolGroup/lv_root is mounted on /; on-line resizing required
old desc_blocks = , new_desc_blocks =
Performing an on-line resize of /dev/VolGroup/lv_root to  (4k) blocks.
The filesystem on /dev/VolGroup/lv_root is now  blocks long.

接下来是新增独立的vg，重新划分，而不是在原来已经划分好的基础上

[root@localhost ~]# fdisk /dev/xvdc 　　#fdisk 新增磁盘名（这里我将一块磁盘划分了4个分区，所以这里内容有点多重复的也多）
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x9f0be0ba.
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  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 (-)
p
Partition number (-):
First cylinder (-, default ):
Using default value
Last cylinder, +cylinders or +size{K,M,G} (-, default ): +24G

Command (m for help): n
Command action
   e   extended
   p   primary partition (-)
p
Partition number (-):
First cylinder (-, default ):
Using default value
Last cylinder, +cylinders or +size{K,M,G} (-, default ): +125G

Command (m for help): n
Command action
   e   extended
   p   primary partition (-)
p
Partition number (-):
First cylinder (-, default ):
Using default value
Last cylinder, +cylinders or +size{K,M,G} (-, default ): +64G 

Command (m for help): n
Command action
   e   extended
   p   primary partition (-)
p
Selected partition
First cylinder (-, default ):
Using default value
Last cylinder, +cylinders or +size{K,M,G} (-, default ):
Using default value 

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

Command (m for help): t
Partition number (-): 2　　　　　　#每一个分区都需要分别选择类型
Hex code (type L to list codes): 8e
Changed system type of partition  to 8e (Linux LVM)

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

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

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

Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# mkdir /tmp　　　　　　#创建相应的挂载分区，嗯嗯，我这里是错误示范，这几个文件夹是系统自带的，我删掉之后就出现问题，所以自己另起个名字吧
[root@localhost ~]# mkdir /var
[root@localhost ~]# mkdir /srv/Bigdata
[root@localhost ~]# mkdir /opt
[root@localhost ~]# vgcreate datavg /dev/xvdc　　　　
xvdc   xvdc1  xvdc2  xvdc3  xvdc4
[root@localhost ~]# vgcreate datavg /dev/xvdc1 /dev/xvdc2 /dev/xvdc3 /dev/xvdc4 　　#这里好像是在执行vgcreate时同时执行pvcreate了

#新增vg，只有在vg里面的lv才能动态扩展

Physical volume "/dev/xvdc1" successfully created 
Physical volume "/dev/xvdc2" successfully created 
Physical volume "/dev/xvdc3" successfully created 
Physical volume "/dev/xvdc4" successfully created 
Volume group "datavg" successfully created 

[root@localhost ~]# lvcreate -n tmplv +24G datavg　　　　　
Please specify either size or extents
Run `lvcreate --help' for more information.
[root@localhost ~]# lvcreate -n tmplv -L +23G datavg　　　　#增加一个lv，这个lv是用来挂载分区的
Logical volume "tmplv" created
[root@localhost ~]# mkfs.ext4 /dev/datavg/tmplv 　　　　　　#挂载独立分区时就需要进行mkfs格式化，后面跟的是lv路径，可以使用lvdisplay查看
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
1507328 inodes, 6029312 blocks
301465 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
184 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, 2654208,
4096000

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

This filesystem will be automatically checked every 28 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@localhost ~]# mount /dev/datavg/tmplv /tmp    #挂载时使用的是mount lv路径（也是lvdisplay查看） 挂载路径，注意，这条命令最好加入/etc/fstab里面，加入之后就可以开机自动挂载了
[root@localhost ~]# lvcreate -n varlv -L +124G datavg　　#接下来这些就是新增第二第三第四个分区了
Logical volume "varlv" created
[root@localhost ~]# mkfs.ext4 /dev/datavg/varlv
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
8126464 inodes, 32505856 blocks
1625292 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
992 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, 2654208,
4096000, 7962624, 11239424, 20480000, 23887872

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

This filesystem will be automatically checked every 21 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@localhost ~]# mount /dev/datavg/varlv /var
[root@localhost ~]# lvcreate -n datalv -L +63G datavg
Logical volume "datalv" created
[root@localhost ~]# mkfs.ext4 /dev/datavg/datalv
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
4128768 inodes, 16515072 blocks
825753 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
504 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, 2654208,
4096000, 7962624, 11239424

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

This filesystem will be automatically checked every 33 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@localhost ~]# mount /dev/datavg/datalv /srv/Bigdata
[root@localhost ~]# lvcreate -n optlv -L +310G datavg
Volume group "datavg" has insufficient free space (79356 extents): 79360 required
.[root@localhost ~]# lvcreate -n optlv -L +309G datavg
Logical volume "optlv" created
[root@localhost ~]# mkfs.ext4 /dev/datavg/optlv
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
20250624 inodes, 81002496 blocks
4050124 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
2472 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, 2654208,
4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968

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

This filesystem will be automatically checked every 31 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@localhost ~]# mount /dev/datavg//opt
datalv optlv tmplv varlv
[root@localhost ~]# mount /dev/datavg/optlv /opt

e2fsck -f /dev/storage/vo 检查磁盘完整性
resize2fs /dev/storage/vo 重置硬盘容量（应该是相当于更新磁盘的意思吧）,扩容的话是先扩容再检查最后重置并挂载，减容的话就是先检查磁盘完整性再重置大小并挂载
mount -a
df -h 查看磁盘容量
umount /bplvm 为后面缩小逻辑卷做准备
e2fsck -f /dev/storage/vo
resize2fs /dev/storage/vo 120M 将磁盘容量减少至120M
lvreduce -L 120M /dev/storage/vo 减少120M（如果执行完上面那条命令再执行这条，应该会减为0M了吧，没试过）

删除逻辑卷：
umount /bplvm
vim /etc/fstab 删除自己添加的那条挂载vo的命令的那行
lvremove /dev/storage/vo 删除LV逻辑卷设备
vgremove storage 删除VG卷组
pvremove /dev/sdb /dev/sdc 删除PV物理卷设备
注意删除的顺序是按照上面的删除顺序的，跟增加时正好相反，不能乱来