小记"/>
Linux LVM使用小记
对于Linux LVM一直不太理解，直到最近使用了简单功能后才稍微明白点。
对于硬盘空间物理上的使用，我们都是先对硬盘进行分区，然后格式化成文件系统支持的类型，最后给操作系统使用。但是这种使用方式很不灵活，分完区之后如果想动态扩大或者缩小容量需要格式化硬盘后重新分区调整。LVM正好可以解决这个问题，提供一种灵活可变的硬盘空间使用方式。
LVM的基本结构如下图：
其中Disk Partition是物理硬盘分区，我们需要在每个物理分区上建立对应的PV（物理卷），Disk Partition和PV应该是一一对应的。VG是一个逻辑层，将所有PV的资源进行整合，形成一个存储池。然后可以将VG再细分为LV（逻辑卷），LV是最后提供给操作系统使用的卷。
本文将对一个已建立的LVM进行硬盘的扩容，步骤如下：
1、查看分区情况
# fdisk -lDisk /dev/sda: 966.4 GB, 966367641600 bytes 255 heads, 63 sectors/track, 117487 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: 0x0003f3bdDevice Boot Start End Blocks Id System /dev/sda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 64 10444 83373056 8e Linux LVM /dev/sda3 10444 78325 545259482+ 83 Linux /dev/sda4 78326 117487 314568765 83 LinuxDisk /dev/mapper/vg_template-lv_root: 875.1 GB, 875099586560 bytes 255 heads, 63 sectors/track, 106391 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: 0x00000000Disk /dev/mapper/vg_template-lv_swap: 8405 MB, 8405385216 bytes 255 heads, 63 sectors/track, 1021 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: 0x00000000Disk /dev/mapper/vg_template-lv_home: 23.3 GB, 23278387200 bytes 255 heads, 63 sectors/track, 2830 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: 0x00000000View Code
可以看到硬盘目前966G左右，已经使用900G，我将为LVM再分配30G进去。
2、可以通过命令pvscan和pvdisplay查看目前已有的PV
# pvscanPV /dev/sda2 VG vg_template lvm2 [79.51 GiB / 0 free]PV /dev/sda3 VG vg_template lvm2 [520.00 GiB / 0 free]PV /dev/sda4 VG vg_template lvm2 [299.99 GiB / 54.99 GiB freeTotal: 3 [899.50 GiB] / in use: 3 [899.50 GiB] / in no VG: 0 [0View Code
# pvdisplay--- Physical volume ---PV Name /dev/sda2VG Name vg_templatePV Size 79.51 GiB / not usable 3.00 MiBAllocatable yes (but full)PE Size 4.00 MiBTotal PE 20354Free PE 0Allocated PE 20354PV UUID cf72cq-WGB1-AIdu-dUuN-NhGA-qXtL-2lIPSC--- Physical volume ---PV Name /dev/sda3VG Name vg_templatePV Size 520.00 GiB / not usable 3.96 MiBAllocatable yes (but full)PE Size 4.00 MiBTotal PE 133119Free PE 0Allocated PE 133119PV UUID os0owi-lP6g-3QXI-p3SF-OVYN-Dmwq-t4bcgq--- Physical volume ---PV Name /dev/sda4VG Name vg_templatePV Size 300.00 GiB / not usable 4.06 MiBAllocatable yesPE Size 4.00 MiBTotal PE 76798Free PE 14077Allocated PE 62721PV UUID fSH2ET-c01w-pRdK-FlE1-Rf4l-kem4-Sk5keDView Code
3、也可以通过vgdisplay查看VG中的剩余空间
# vgdisplay--- Volume group ---VG Name vg_templateSystem IDFormat lvm2Metadata Areas 3Metadata Sequence No 12VG Access read/writeVG Status resizableMAX LV 0Cur LV 3Open LV 3Max PV 0Cur PV 3Act PV 3VG Size 899.50 GiBPE Size 4.00 MiBTotal PE 230271Alloc PE / Size 216194 / 844.51 GiBFree PE / Size 14077 / 54.99 GiBVG UUID YjcKe2-688m-1Iar-Zpa6-vbE7-TuXf-A1sgvhView Code
可以看到，VG中海油54G左右的空间
4、查看目前已有的LV
# lvdisplay--- Logical volume ---LV Path /dev/vg_template/lv_rootLV Name lv_rootVG Name vg_templateLV UUID QzjkFn-VtVG-ruvw-Mpr4-UpjH-Mjpf-e6TSdKLV Write Access read/writeLV Creation host, time Template, 2014-09-05 20:52:37 +0800LV Status available# open 1LV Size 815.00 GiBCurrent LE 208640Segments 3Allocation inheritRead ahead sectors auto- currently set to 1024Block device 253:0--- Logical volume ---LV Path /dev/vg_template/lv_homeLV Name lv_homeVG Name vg_templateLV UUID PSnzWl-xeGd-aKP9-EmNL-8vxK-sMIn-z6KMDELV Write Access read/writeLV Creation host, time Template, 2014-09-05 20:52:40 +0800LV Status available# open 1LV Size 21.68 GiBCurrent LE 5550Segments 1Allocation inheritRead ahead sectors auto- currently set to 1024Block device 253:2--- Logical volume ---LV Path /dev/vg_template/lv_swapLV Name lv_swapVG Name vg_templateLV UUID z4oFd5-IvA9-Y0EY-KcC1-oaOr-QZEF-7IAZSlLV Write Access read/writeLV Creation host, time Template, 2014-09-05 20:52:42 +0800LV Status available# open 1LV Size 7.83 GiBCurrent LE 2004Segments 1Allocation inheritRead ahead sectors auto- currently set to 1024Block device 253:1View Code
此次将给lv_root增加容量
5、增加LV容量
# lvextend -L +30G /dev/vg_template/lv_rootExtending logical volume lv_root to 845.00 GiBLogical volume lv_root successfully resizedView Code
6、查看增加后的LV容量
# lvdisplay /dev/vg_template/lv_root --- Logical volume ---LV Path /dev/vg_template/lv_rootLV Name lv_rootVG Name vg_templateLV UUID QzjkFn-VtVG-ruvw-Mpr4-UpjH-Mjpf-e6TSdKLV Write Access read/writeLV Creation host, time Template, 2014-09-05 20:52:37 +0800LV Status available# open 1LV Size 845.00 GiBCurrent LE 216320Segments 3Allocation inheritRead ahead sectors auto- currently set to 1024Block device 253:0View Code
可以看到容量从815增加至845G
7、通过df查看磁盘空间
# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_template-lv_root803G 732G 30G 97% / tmpfs 32G 25G 6.7G 79% /dev/shm /dev/sda1 485M 38M 423M 9% /boot /dev/mapper/vg_template-lv_home22G 559M 20G 3% /homeView Code
发现操作系统层面看，使用空间没有变。
8、通过resize2fs重新扫描使用空间
# resize2fs /dev/vg_template/lv_root resize2fs 1.41.12 (17-May-2010) Filesystem at /dev/vg_template/lv_root is mounted on /; on-line resizing required old desc_blocks = 51, new_desc_blocks = 53 Performing an on-line resize of /dev/vg_template/lv_root to 221511680 (4k) blocks. The filesystem on /dev/vg_template/lv_root is now 221511680 blocks long.View Code
9、再通过df查看使用空间，空间已经扩大
]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_template-lv_root832G 732G 58G 93% / tmpfs 32G 25G 6.7G 79% /dev/shm /dev/sda1 485M 38M 423M 9% /boot /dev/mapper/vg_template-lv_home22G 559M 20G 3% /homeView Code
以后继续补充如何将新加硬盘如何操作。
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以上是针对VG有剩余空间直接扩充LV的过程，下面介绍一下对于新加物理硬盘如何加到VG中。
1、查看新建物理磁盘情况
fdisk -l
Disk /dev/sdb: 214.7 GB, 214748364800 bytes
255 heads, 63 sectors/track, 26108 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
可以看到有一个200G左右的磁盘—/dev/sdb
2、对/dev/sdb进行分区
fdisk /dev/sdb
]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x94b29f79.
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):
输入n，新建分区，根据实际情况选择主分区或者扩展分区，这里我选择主分区
Command (m for help): n
Command actione extendedp primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-26108, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-26108, default 26108):
Using default value 26108Command (m for help): View Code 输入t，确定分区格式，8e代表Linux LVM
Command (m for help): t Selected partition 1 Hex code (type L to list codes): 8e Changed system type of partition 1 to 8e (Linux LVM)View Code
输入p，查看分区状况，输入w，保存分区配置
Command (m for help): pDisk /dev/sdb: 214.7 GB, 214748364800 bytes 255 heads, 63 sectors/track, 26108 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: 0x94b29f79Device Boot Start End Blocks Id System /dev/sdb1 1 26108 209712478+ 8e Linux LVMCommand (m for help): w The partition table has been altered!Calling ioctl() to re-read partition table. Syncing disks.View Code
3、新建PV
# pvcreate /dev/sdb1Physical volume "/dev/sdb1" successfully createdView Code
4、将新建PV加到VG中
# vgdisplay--- Volume group ---VG Name vg_templateSystem IDFormat lvm2Metadata Areas 3Metadata Sequence No 13VG Access read/writeVG Status resizableMAX LV 0Cur LV 3Open LV 3Max PV 0Cur PV 3Act PV 3VG Size 899.50 GiBPE Size 4.00 MiBTotal PE 230271Alloc PE / Size 223874 / 874.51 GiBFree PE / Size 6397 / 24.99 GiBVG UUID YjcKe2-688m-1Iar-Zpa6-vbE7-TuXf-A1sgvh[root@SICS-MIGPC-DB ~]# vgextend vg_template /dev/sdb1Volume group "vg_template" successfully extended [root@SICS-MIGPC-DB ~]# vgdisplay--- Volume group ---VG Name vg_templateSystem IDFormat lvm2Metadata Areas 4Metadata Sequence No 14VG Access read/writeVG Status resizableMAX LV 0Cur LV 3Open LV 3Max PV 0Cur PV 4Act PV 4VG Size 1.07 TiBPE Size 4.00 MiBTotal PE 281470Alloc PE / Size 223874 / 874.51 GiBFree PE / Size 57596 / 224.98 GiBVG UUID YjcKe2-688m-1Iar-Zpa6-vbE7-TuXf-A1sgvhView Code
然后根据之前步骤扩展现有LV空间即可。
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其他常用命令：
1、从VG新建LV，并格式化LV为特定文件系统
新建一个100G的新LV，名称为VPS
#lvcreate –L 100G –n vps /dev/vg_template;View Code
格式化为EXT3文件系统格式
#mkfs –t ext3 /dev/vg_template/vpsView Code
2、从VG删除PV，删除硬盘上的LVM分区，去掉硬盘
#vgreduce vg_template /dev/sdb1; #pvremove /dev/sdb1 #fdisk /dev/sdb1 输入P，输入D（删除），输入P查看，输入W，保存配置。View Code
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Linux LVM使用小记
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