标签：physical volume 逻辑卷 linux lvm2 磁盘管理
LVM是逻辑盘卷管理（Logical Volume Manager）的简称，它是Linux环境下对磁盘分区进行管理的一种机制，LVM是建立在硬盘和分区之上的一个逻辑层，来提高磁盘分区管理的灵活性，通过LVM管理员就不必将磁盘的文件移动到新的磁盘上以充分利用新的存储空间，而是直接扩展文件系统跨越磁盘即可，也就是我们常说的动态调整分区的大小。
LVM的一些术语，这些也是学习LVM之前必知的知识，我在网上找到一篇文章，关于这些术语方面介绍的比较详细。
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)。 可以做这样一个设想来理解以上三者的关系：如果把PV比做地球的一个板块，VG则是一个地球，因为地球是由多个板块组成的，而在地球上划分一个区域并标记为亚洲，那么亚洲就相当于一个LVM。
PE（physical extent）
每一个物理卷被划分为称为PE(Physical Extents)的基本单元，（我理解为物理块，下面的LE则是对应逻辑块）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
首先我们先准备好虚拟机，这次实验准备的是CentOS6.6的版本，并在此基础上添加几块磁盘，过程如下：
1) 在下图设备项内鼠标单击选择硬盘
鼠标单击硬盘项之后会出现下图，选择上硬盘之后我们在单击下方的添加硬盘
这里一路下一步即可，根据自己的实验需求进行添加硬盘数量
添加完成之后可以看到设备项内的硬盘已经添加成功了！
下面我们开机进入CentOS系统
先查看一下我们系统所有磁盘设备的识别情况及编号(/dev/sdb,/dev/sdc,/dev/sdd,/dev/sde)
[root@Lab6-1 ~]# fdisk -l Disk /dev/sda: 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: 0x000f3537 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 2611 20458496 8e Linux LVM 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: 0x00000000 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 Disk /dev/sdd: 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 Disk /dev/sde: 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 Disk /dev/mapper/vg_lab1-lv_root: 18.9 GB, 18865979392 bytes 255 heads, 63 sectors/track, 2293 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 Disk /dev/mapper/vg_lab1-lv_swap: 2080 MB, 2080374784 bytes 255 heads, 63 sectors/track, 252 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
pv相关常用命令：
1.pvcreate: 创建pv命令
[root@Lab6-1 ~]# pvcreate /dev/sdb /dev/sdc Physical volume "/dev/sdb" successfully created Physical volume "/dev/sdc" successfully created
2.pvs：查看指定或所有pv简要信息
[root@Lab6-1 ~]# pvs PV VG Fmt Attr PSize PFree /dev/sda2 vg_lab1 lvm2 a-- 19.51g 0 /dev/sdb lvm2 --- 20.00g 20.00g /dev/sdc lvm2 --- 20.00g 20.00g [root@Lab6-1 ~]# pvs /dev/sdb PV VG Fmt Attr PSize PFree /dev/sdb lvm2 --- 20.00g 20.00g
3.pvdisplay:查看指定或所有pv的更详细信息
[root@Lab6-1 ~]# pvdisplay /dev/sdb /dev/sdc "/dev/sdb" is a new physical volume of "20.00 GiB" --- NEW Physical volume --- PV Name /dev/sdb VG Name PV Size 20.00 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID TQ5RI0-oWGj-Kf6Q-eoNJ-ZCMN-q5Jf-SYokrx "/dev/sdc" is a new physical volume of "20.00 GiB" --- NEW Physical volume --- PV Name /dev/sdc VG Name PV Size 20.00 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID Czisys-v7cm-SxMP-IynN-0GqC-NW5d-EzYRn1
4.pvscan:扫描系统上的所有pv
[root@Lab6-1 ~]# pvscan PV /dev/sda2 VG vg_lab1 lvm2 [19.51 GiB / 0 free] PV /dev/sdb lvm2 [20.00 GiB] PV /dev/sdc lvm2 [20.00 GiB] Total: 3 [59.51 GiB] / in use: 1 [19.51 GiB] / in no VG: 2 [40.00 GiB]
5.pvremove: 移除pv
[root@Lab6-1 ~]# pvremove /dev/sdc Labels on physical volume "/dev/sdc" successfully wiped
vg相关常用命令：
1.vgcreate：首次创建一个vg时使用，这里vgcreate 后要指定vg的名字(VG_NAME) 在跟需要添加进vg的pv设备
[root@Lab6-1 ~]# vgcreate myvg /dev/sdb Volume group "myvg" successfully created [root@Lab6-1 ~]# vgcreate myvg /dev/sdb /dev/sdc Physical volume "/dev/sdc" successfully created Volume group "myvg" successfully created
2.vgs:查看指定或所有vg简要信息
[root@Lab6-1 ~]# vgs VG #PV #LV #SN Attr VSize VFree myvg 2 0 0 wz--n- 39.99g 39.99g vg_lab1 1 2 0 wz--n- 19.51g 0 [root@Lab6-1 ~]# vgs myvg VG #PV #LV #SN Attr VSize VFree myvg 2 0 0 wz--n- 39.99g 39.99g
3.vgdisplay:查看指定或所有vg的更详细信息
[root@Lab6-1 ~]# vgdisplay myvg --- Volume group --- VG Name myvg System ID Format lvm2 Metadata Areas 2 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 2 Act PV 2 VG Size 39.99 GiB PE Size 4.00 MiB Total PE 10238 Alloc PE / Size 0 / 0 Free PE / Size 10238 / 39.99 GiB VG UUID 0hflFu-aoBa-0URf-m509-6wWj-QMrp-79LYeR
4.vgextend:扩展vg大小
[root@Lab6-1 ~]# pvcreate /dev/sdd Physical volume "/dev/sdd" successfully created [root@Lab6-1 ~]# vgextend myvg /dev/sdd Volume group "myvg" successfully extended [root@Lab6-1 ~]# vgs VG #PV #LV #SN Attr VSize VFree myvg 3 0 0 wz--n- 59.99g 59.99g vg_lab1 1 2 0 wz--n- 19.51g 0 [root@Lab6-1 ~]# pvs PV VG Fmt Attr PSize PFree /dev/sda2 vg_lab1 lvm2 a-- 19.51g 0 /dev/sdb myvg lvm2 a-- 20.00g 20.00g /dev/sdc myvg lvm2 a-- 20.00g 20.00g /dev/sdd myvg lvm2 a-- 20.00g 20.00g
5.vgreduce:缩减vg大小，从vg移除某pv
[root@Lab6-1 ~]# vgreduce myvg /dev/sdd Removed "/dev/sdd" from volume group "myvg" [root@Lab6-1 ~]# vgs VG #PV #LV #SN Attr VSize VFree myvg 2 0 0 wz--n- 39.99g 39.99g vg_lab1 1 2 0 wz--n- 19.51g 0 [root@Lab6-1 ~]# pvs PV VG Fmt Attr PSize PFree /dev/sda2 vg_lab1 lvm2 a-- 19.51g 0 /dev/sdb myvg lvm2 a-- 20.00g 20.00g /dev/sdc myvg lvm2 a-- 20.00g 20.00g /dev/sdd lvm2 --- 20.00g 20.00g
6.vgremove:移除vg
[root@Lab6-1 ~]# vgremove myvg Volume group "myvg" successfully removed [root@Lab6-1 ~]# vgs VG #PV #LV #SN Attr VSize VFree vg_lab1 1 2 0 wz--n- 19.51g 0 [root@Lab6-1 ~]# pvs PV VG Fmt Attr PSize PFree /dev/sda2 vg_lab1 lvm2 a-- 19.51g 0 /dev/sdb lvm2 --- 20.00g 20.00g /dev/sdc lvm2 --- 20.00g 20.00g /dev/sdd lvm2 --- 20.00g 20.00g
lv相关常用命令：
lvcreate：首次创建一个lv时使用，格式：lvcreate -L # -n LV_NAME VG_NAME
-L: 指定lv卷的大小
-n：设定lv卷名字
[root@Lab6-1 ~]# lvcreate -L 10G -n my_lv myvg Logical volume "my_lv" created
2.lvs：查看指定或所有lv简要信息
[root@Lab6-1 ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert my_lv myvg -wi-a----- 10.00g lv_root vg_lab1 -wi-ao---- 17.57g lv_swap vg_lab1 -wi-ao---- 1.94g
3.lvdisplay:查看指定或所有lv的更详细信息，创建lv之后会把lv识别成设备文件，路径为/dev/VG_NAME/LV_NAME 而不在是lv卷的名字
[root@Lab6-1 ~]# lvdisplay /dev/myvg/my_lv --- Logical volume --- LV Path /dev/myvg/my_lv LV Name my_lv VG Name myvg LV UUID g0n789-ZVMz-xtgN-Qixv-wTye-cCY6-pk15sc LV Write Access read/write LV Creation host, time Lab6-1, 2015-09-22 22:39:33 -0400 LV Status available # open 0 LV Size 10.00 GiB Current LE 2560 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:2
4.lvextend:扩展lv卷物理边界大小，这里扩展大小有两种方式 例如：+5G表示原有空间增加5G 5G表示将空间扩展至5G
resize2fs：调整lv文件系统边界大小，只有同时扩展完成才可以使用生效
[root@Lab6-1 ~]# lvextend -L 15G /dev/myvg/my_lv # 调整lv大小至15G Size of logical volume myvg/my_lv changed from 10.00 GiB (2560 extents) to 15.00 GiB (3840 extents). Logical volume my_lv successfully resized [root@Lab6-1 ~]# mke2fs -t ext4 /dev/myvg/my_lv 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 655360 inodes, 2621440 blocks 131072 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=2684354560 80 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 Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 26 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override. [root@Lab6-1 ~]# mount /dev/myvg/my_lv /mnt/ [root@Lab6-1 ~]# mount /dev/mapper/vg_lab1-lv_root on / type ext4 (rw) 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) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) /dev/mapper/myvg-my_lv on /mnt type ext4 (rw) [root@Lab6-1 ~]# lvextend -L 15G /dev/myvg/my_lv # 调整lv大小至15G Size of logical volume myvg/my_lv changed from 10.00 GiB (2560 extents) to 15.00 GiB (3840 extents). Logical volume my_lv successfully resized [root@Lab6-1 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_lab1-lv_root 18G 3.9G 13G 24% / tmpfs 491M 0 491M 0% /dev/shm /dev/sda1 477M 28M 424M 7% /boot /dev/mapper/myvg-my_lv 9.8G 23M 9.2G 1% /mnt [root@Lab6-1 ~]# resize2fs /dev/myvg/my_lv # 不指明大小，表示扩展至跟物理边界一样大 resize2fs 1.41.12 (17-May-2010) Filesystem at /dev/myvg/my_lv is mounted on /mnt; on-line resizing required old desc_blocks = 1, new_desc_blocks = 1 Performing an on-line resize of /dev/myvg/my_lv to 3932160 (4k) blocks. The filesystem on /dev/myvg/my_lv is now 3932160 blocks long. [root@Lab6-1 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_lab1-lv_root 18G 3.9G 13G 24% / tmpfs 491M 0 491M 0% /dev/shm /dev/sda1 477M 28M 424M 7% /boot /dev/mapper/myvg-my_lv 15G 25M 14G 1% /mnt
5.lvreduce：缩减lv物理边界大小
resize2fs:调整文件系统边界大小
[root@Lab6-1 ~]# umount /mnt # 必须要先卸载 [root@Lab6-1 ~]# e2fsck -f /dev/myvg/my_lv # 必须强制检查一次文件系统 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/myvg/my_lv: 11/983040 files (0.0% non-contiguous), 100864/3932160 blocks [root@Lab6-1 ~]# resize2fs /dev/myvg/my_lv 10G # 文件系统大小缩减至10G resize2fs 1.41.12 (17-May-2010) Resizing the filesystem on /dev/myvg/my_lv to 2621440 (4k) blocks. The filesystem on /dev/myvg/my_lv is now 2621440 blocks long. [root@Lab6-1 ~]# lvreduce -L 10G /dev/myvg/my_lv # 物理边界缩减至10G WARNING: Reducing active logical volume to 10.00 GiB THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce my_lv? [y/n]: y # 这是危险操作是否确认 Size of logical volume myvg/my_lv changed from 15.00 GiB (3840 extents) to 10.00 GiB (2560 extents). Logical volume my_lv successfully resized [root@Lab6-1 ~]# mount /dev/myvg/my_lv /mnt [root@Lab6-1 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_lab1-lv_root 18G 3.9G 13G 24% / tmpfs 491M 0 491M 0% /dev/shm /dev/sda1 477M 28M 424M 7% /boot /dev/mapper/myvg-my_lv
6.lvremove：移除lv
[root@Lab6-1 ~]# lvremove /dev/myvg/my_lv Do you really want to remove active logical volume my_lv? [y/n]: y Logical volume "my_lv" successfully removed
6.为lv创建快照，-p r：设置权限为只读，-s：创建快照选项
[root@Lab6-1 ~]# lvcreate -s -L 10G -n my_lv_snapshot -p r /dev/myvg/my_lv Logical volume "my_lv_snapshot" created [root@Lab6-1 ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert my_lv myvg owi-aos--- 10.00g my_lv_snapshot myvg sri-a-s--- 10.00g my_lv 0.00 lv_root vg_lab1 -wi-ao---- 17.57g lv_swap vg_lab1 -wi-ao---- 1.94g
完。
标签：physical volume 逻辑卷 linux lvm2 磁盘管理
原文地址：http://corazon.blog.51cto.com/9658694/1699612
