1. LVM（Logical Volume Manager):
可以弹性调整文件系统的容量，即把多个物理分区整合为像一个磁盘一样，实现文件系统自由扩展，缩减
2. LVM的组成：
PV（Physical Volume):物理卷
LVM基本的逻辑储存块，但比基本的物理储存块（分区，硬盘等）多出一些LVM有关的管理参数
VG (Volume Group): 卷组
由多个PV组成，类似于非LVM系统中的物理硬盘.
LV （Logical Volume):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 Extend):物理扩展块
相当于文件系统中的block，调整PE会影响到VG的最大容量
LVM各组件之间的关系图示：
3.具体实现流程：
（1）先划分4个分区，每个分区10G,systemID为8e
(2) 4个分区整合成一个VG,每个PE16M,vg名为“textvg"
(3) 把VG容量划分LV,LV名为“textlv”
(4) 然后把LV格式化为ext4文件系统，并挂载到/mnt/lvm中
划分分区：
Command (m for help): p
Disk /dev/sda: 128.8 GB, 128849018880 bytes
255 heads, 63 sectors/track, 15665 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: 0x0004aa62
Device Boot Start End Blocks Id System
/dev/sda1 * 1 26 204800 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 26 7859 62914560 8e Linux LVM
/dev/sda3 7859 7923 521113+ 83 Linux
/dev/sda4 7924 15665 62187615 5 Extended
Command (m for help): n #添加新分区
First cylinder (7924-15665, default 7924): #指定柱面号，选择默认即可
Using default value 7924
Last cylinder, +cylinders or +size{K,M,G} (7924-15665, default 15665): +10G #指定分区大小
Command (m for help): t #指定分区类型
Partition number (1-5): 5 #指定类型的分区号
Hex code (type L to list codes): 8e #指定为8e,即Linux LVM
Changed system type of partition 5 to 8e (Linux LVM)
Command (m for help): w #w保存创建分区
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.创建完以后内核无法读取新建分区表信息，通过partx -a 命令告知内核：
[root@localhost ~]# partx -a /dev/sda 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 BLKPG: Device or resource busy error adding partition 4 BLKPG: Device or resource busy error adding partition 5 BLKPG: Device or resource busy error adding partition 6 BLKPG: Device or resource busy error adding partition 7
然后分区信息就可以通过fdisk -l 看到了：
[root@localhost ~]# fdisk -l Disk /dev/sda: 128.8 GB, 128849018880 bytes 255 heads, 63 sectors/track, 15665 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: 0x0004aa62 Device Boot Start End Blocks Id System /dev/sda1 * 1 26 204800 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 26 7859 62914560 8e Linux LVM /dev/sda3 7859 7923 521113+ 83 Linux /dev/sda4 7924 15665 62187615 5 Extended /dev/sda5 7924 9229 10490413+ 8e Linux LVM /dev/sda6 9230 10535 10490413+ 8e Linux LVM /dev/sda7 10536 11841 10490413+ 8e Linux LVM
上边sda5-sda7即为我们创建的新分区
4.创建PV:
常用工具
pvcreate: 将物理分区新建为PV
pvscan: 简要显示PV信息
pvdisplay: 显示PV详细信息
root@localhost ~]# pvscan #查看当前系统是否有PV,一下为以前创建
PV /dev/sda2 VG vg0 lvm2 [59.99 GiB / 7.99 GiB free]
Total: 1 [59.99 GiB] / in use: 1 [59.99 GiB] / in no VG: 0 [0 ]
[root@localhost ~]# pvcreate /dev/sda{5,6,7,8}#一起创建分区5，6，7,8
Physical volume "/dev/sda5" successfully created
Physical volume "/dev/sda6" successfully created
Physical volume "/dev/sda7" successfully created
Physical volume "/dev/sda8" successfully created[root@localhost ~]# pvscan PV /dev/sda5 lvm2 [10.00 GiB] PV /dev/sda6 lvm2 [10.00 GiB] PV /dev/sda7 lvm2 [10.00 GiB] PV /dev/sda8 lvm2 [10.00 GiB]
详细列出PV信息：
[root@localhost ~]# pvdisplay "/dev/sda5" is a new physical volume of "10.00 GiB" --- NEW Physical volume --- PV Name /dev/sda5 #分区设备名称 VG Name PV Size 10.00 GiB #PV容量大小 Allocatable NO #是否被分配 PE Size 0 #PE大小 Total PE 0 #共有几个PE Free PE 0 #空余的PE Allocated PE 0 #未被分配的PE数量 PV UUID fbU7AS-pATY-CTt4-be8l-l72p-zFnP-qGBKk7#PV的UUID
5.创建VG:
常用工具：
vgscan:显示vg简要信息
vgdisplay:显示vg详细信息
vgcreate:创建vg
vgextend:扩充vg大小
vgreduce:缩减vg大小，前提先pvremove PV
[root@localhost ~]# vgcreate -s 16M textvg /dev/sda{5,6,7}
Volume group "textvg" successfully created
[root@localhost ~]# vgscan
Reading all physical volumes. This may take a while...
Found volume group "textvg" using metadata type lvm2VG创建成功
[root@localhost ~]# pvscan PV /dev/sda5 VG textvg lvm2 [10.00 GiB / 10.00 GiB free] PV /dev/sda6 VG textvg lvm2 [10.00 GiB / 10.00 GiB free] PV /dev/sda7 VG textvg lvm2 [10.00 GiB / 10.00 GiB free] PV /dev/sda8 lvm2 [10.00 GiB]
[root@localhost ~]# vgdisplay --- Volume group --- VG Name textvg 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 #VG大小为30G PE Size 16.00 MiB Total PE 1920 Alloc PE / Size 0 / 0 Free PE / Size 1920 / 30.00 GiB VG UUID m6wlkq-7bzX-qkwN-NK5j-wTEJ-mXt0-qewikv
上图为vg的详细信息
如果我们想要增加VG的容量，我们可以把剩余的sda8扩展到VG里
[root@localhost ~]# vgextend textvg /dev/sda8 Volume group "textvg" successfully extended [root@localhost ~]# vgdisplay --- Volume group --- VG Name textvg System ID Format lvm2 Metadata Areas 4 Metadata Sequence No 2 VG Access read/write VG Status resizable MAX LV 0 Cur LV 0 Open LV 0 Max PV 0 Cur PV 4 Act PV 4 VG Size 40.00 GiB #VG大小由30G增加到40G PE Size 16.00 MiB Total PE 2560 Alloc PE / Size 0 / 0 Free PE / Size 2560 / 40.00 GiB VG UUID m6wlkq-7bzX-qkwN-NK5j-wTEJ-mXt0-qewikv
6.创建LV
命令为lvcreate 创建lv
-l:后接PE的个数
-L：后接PE的大小
-n: 后接LV的名称
......
其他命令同上
[root@localhost ~]# lvcreate -L 40G -n textlv textvg#将整个VG空间分配给LV,大小为40G Logical volume "textlv" created#创建成功 [root@localhost ~]# lvdisplay#查看一下LV的详细信息 --- Logical volume --- LV Path /dev/textvg/textlv LV Name textlv VG Name textvg LV UUID wvK7EH-Mumg-chhg-XIZ2-fBfv-Feoz-td8Zr6 LV Write Access read/write LV Creation host, time localhost.localdomain, 2015-08-16 09:52:55 +0800 LV Status available # open 0 LV Size 40.00 GiB#大小即为40G Current LE 2560 Segments 4 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:4
接下来就是为LV格式化文件系统和挂载：
[root@localhost ~]# mkfs -t ext4 /dev/textvg/textlv #格式化LV为ext4格式 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 2621440 inodes, 10485760 blocks 524288 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=4294967296 320 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 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 ~]# mkdir /mnt/lvm#新建一个挂载点 [root@localhost ~]# mount /dev/textvg/textlv /mnt/lvm/#挂载LV到挂载点 [root@localhost ~]# df#查看磁盘信息最后一行 Filesystem 1K-blocks Used Available Use% Mounted on /dev/mapper/vg0-root 20511356 306004 19156776 2% / tmpfs 502176 0 502176 0% /dev/shm /dev/sda1 194241 27901 156100 16% /boot /dev/mapper/vg0-usr 10190136 1963888 7701960 21% /usr /dev/mapper/vg0-var 20511356 201768 19261012 2% /var /dev/sda3 488384 396 461936 1% /mnt/sda3 /dev/mapper/textvg-textlv 41153856 49032 39007672 1% /mnt/lvm #LV创建成功
到此LV就已经创建完成
7.LV扩展：
LVM最大的特点就是可以实现弹性调整磁盘容量
(1)用fdisk添加systemID为8e的分区
(2)用pvcreate创建PV
(3)利用vgextend将PV加入textvg
(4)利用lvresize将加入PV里的PE加入LV中
(5)用resize2fs增加文件系统容量
首先用fdisk添加一个分区sda9具体就不截图了。。
然后创建PV
[root@localhost ~]# pvcreate /dev/sda9#创建新加磁盘sda9到PV Physical volume "/dev/sda9" successfully created [root@localhost ~]# pvscan#列出可以看到sda9已经创建 PV /dev/sda5 VG textvg lvm2 [10.00 GiB / 0 free] PV /dev/sda6 VG textvg lvm2 [10.00 GiB / 0 free] PV /dev/sda7 VG textvg lvm2 [10.00 GiB / 0 free] PV /dev/sda8 VG textvg lvm2 [10.00 GiB / 0 free] PV /dev/sda2 VG vg0 lvm2 [59.99 GiB / 7.99 GiB free] PV /dev/sda9 lvm2 [10.00 GiB] Total: 6 [110.00 GiB] / in use: 5 [99.99 GiB] / in no VG: 1 [10.00 GiB] [root@localhost ~]# vgextend textvg /dev/sda9#加入VG Volume group "textvg" successfully extended [root@localhost ~]# vgdisplay --- Volume group --- VG Name textvg System ID Format lvm2 Metadata Areas 5 Metadata Sequence No 4 VG Access read/write VG Status resizable MAX LV 0 Cur LV 1 Open LV 1 Max PV 0 Cur PV 5 Act PV 5 VG Size 50.00 GiB#加入后由原来的40G达到50G PE Size 16.00 MiB Total PE 3200 Alloc PE / Size 2560 / 40.00 GiB Free PE / Size 640 / 10.00 GiB VG UUID m6wlkq-7bzX-qkwN-NK5j-wTEJ-mXt0-qewikv
[root@localhost ~]# lvresize -L +10G /dev/textvg/textlv #同样放大LV Size of logical volume textvg/textlv changed from 40.00 GiB (2560 extents) to 50.00 GiB (3200 extents). Logical volume textlv successfully resized [root@localhost ~]# lvdisplay --- Logical volume --- LV Path /dev/textvg/textlv LV Name textlv VG Name textvg LV UUID wvK7EH-Mumg-chhg-XIZ2-fBfv-Feoz-td8Zr6 LV Write Access read/write LV Creation host, time localhost.localdomain, 2015-08-16 09:52:55 +0800 LV Status available # open 1 LV Size 50.00 GiB Current LE 3200 Segments 5 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:4
到此扩展结束
大家看到扩展后文件系统并没有增加容量，可以使用resize2fs解决
[root@localhost ~]# df -h /mnt/lvm/#显示到LV大小还是原来的49G. Filesystem Size Used Avail Use% Mounted on /dev/mapper/textvg-textlv 40G 48M 38G 1% /mnt/lvm
[root@localhost ~]# resize2fs /dev/textvg/textlv #resize2fs重新定义文件系统大小 resize2fs 1.41.12 (17-May-2010) Filesystem at /dev/textvg/textlv is mounted on /mnt/lvm; on-line resizing required old desc_blocks = 3, new_desc_blocks = 4 Performing an on-line resize of /dev/textvg/textlv to 13107200 (4k) blocks. The filesystem on /dev/textvg/textlv is now 13107200 blocks long. [root@localhost ~]# df -h /mnt/lvm/#再次列出后就为50G了 Filesystem Size Used Avail Use% Mounted on /dev/mapper/textvg-textlv 50G 52M 47G 1% /mnt/lvm
大家看到lvm大小就为正常的50G 了
既然能扩展同样就能缩减。。
8.LV缩减
我们随便找一个分区抽调出来来实现LV缩减
假如我们抽调/dev/sda8
[root@localhost ~]# pvdisplay /dev/sda8#先查看一下抽调的Sda8的大小 --- Physical volume --- PV Name /dev/sda8 VG Name textvg PV Size 10.00 GiB / not usable 4.54 MiB#这里显示为10G Allocatable yes (but full) #PV大小为10G PE Size 16.00 MiB Total PE 640 Free PE 0 Allocated PE 640 PV UUID c3rW7L-WcGZ-Aghs-VXzZ-XPIw-Onu8-xTK9z4
从上边我们看到sda8的PV size为10G,那我们就缩减10G
首先卸载挂载点，然后用fsck对磁盘进行检测
[root@localhost ~]# umount /mnt/lvm/#卸载挂载点 [root@localhost ~]# fsck -f -t ext4 /dev/textvg/textlv #强制检测分区 fsck from util-linux-ng 2.17.2 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/mapper/textvg-textlv: 11/3276800 files (0.0% non-contiguous), 251699/13107200 blocks
[root@localhost ~]# pvscan #显示一下PV的总量，需要缩减多少 PV /dev/sda5 VG textvg lvm2 [10.00 GiB / 0 free] PV /dev/sda6 VG textvg lvm2 [10.00 GiB / 0 free] PV /dev/sda7 VG textvg lvm2 [10.00 GiB / 0 free] PV /dev/sda8 VG textvg lvm2 [10.00 GiB / 0 free] PV /dev/sda9 VG textvg lvm2 [10.00 GiB / 0 free] Total: 6 [109.99 GiB] / in use: 6 [109.99 GiB] / in no VG: 0 [0 ] [root@localhost ~]# resize2fs /dev/textvg/textlv 40G resize2fs 1.41.12 (17-May-2010) Resizing the filesystem on /dev/textvg/textlv to 10485760 (4k) blocks. The filesystem on /dev/textvg/textlv is now 10485760 blocks long. [root@localhost ~]# mount /dev/textvg/textlv /mnt/lvm/#挂载到/mnt/lvm [root@localhost ~]# df -h /mnt/lvm/ Filesystem Size Used Avail Use% Mounted on /dev/mapper/textvg-textlv 40G 48M 38G 1% /mnt/lvm #这样就缩减到40G
这样就实现了LVM的创建，扩展和缩减。。。。
本文出自 “开源盛世” 博客，请务必保留此出处http://zhaohongfei.blog.51cto.com/6258685/1689898
原文地址：http://zhaohongfei.blog.51cto.com/6258685/1689898
