LVM创建以及使用

LVM(Logical VolumeManager 逻辑卷管理)

在磁盘分区和文件系统之间添加一个逻辑层，来为文件系统屏蔽下层磁盘分区布局，提供一个抽象的盘卷，在盘卷上建立文件系统，来提高磁盘分区管理的灵活性可实现零停机前提下自如对文件系统的大小进行调整，可以方便实现文件系统跨越不同磁盘和分区。下图是我根据自己的理解画出的一张图。此图背景是：公司有一台戴尔R910服务器，现在接上6个SAS硬盘，做成raid5磁盘阵列，最后一个硬盘设为全局热备。然后在戴尔自带的磁盘阵列管理上把剩下的5块硬盘划分为4个VD(虚拟磁盘)，把系统全部安装在第一个VD，然后剩下的3个VD利用LVM技术整合成一个大分区用于存储数据。




下面分享的我创建LV的整个过程，此操作系统为 Red hat enterprise linux 5.5 x86_64 :

------------------------------------- 下面是对VD磁盘的分区管理 ----------------------------------------------------

[root@mail ~]# ls /dev/sd* #查看当前系统有多少分区
/dev/sda /dev/sda1 /dev/sda2 /dev/sda3 /dev/sdb /dev/sdc /dev/sdd

[root@mail ~]# fdisk /dev/sdb #对第二块硬盘进行分区
Device contains neither a valid DOSpartition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes willremain in memory only,
until you decide to write them. After that,of course, the previous
content won't be recoverable.

The number of cylinders for this disk isset to 248029.
There is nothing wrong with that, but thisis larger than 1024,
and could in certain setups cause problemswith:
1) software that runs at boot time (e.g.,old versions of LILO)
2) booting and partitioning software fromother OSs
(e.g., DOS FDISK, OS/2 FDISK)
Warning: invalid flag 0x0000 of partitiontable 4 will be corrected by w(rite)

Command (m for help): m #列出所有帮助信息
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibilityflag
d delete a partition #删除分区
l list known partition types #列出已知的分区类型
m print this menu
n add a new partition #创建新分区
o create a new empty DOSpartition table
p print the partition table #在屏幕打印出所有的分区
q quit without saving changes #退出不保存
s create a new empty Sundisklabel
t change a partition's system id #更改分区的系统ID
u change display/entry units
v verify the partition table
w write table to disk and exit #把当前配置信息写入硬盘并退出
x extra functionality (expertsonly)

Command (m for help): n #创建新分区
Command action
e extended #创建逻辑分区 [ 5,6,7…… ]
p primary partition (1-4) #创建主分区[ 1,2,3,4 ]
p #创建主分区
Partition number (1-4): 1 #创建第一块主分区
First cylinder (1-248029, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK(1-248029, default 248029):
Using default value 248029

Command (m for help): l #列出已知的分区类型

0 Empty 1e Hidden W95 FAT1 80 Old Minix bf Solaris
1 FAT12 24 NEC DOS 81 Minix / old Lin c1 DRDOS/sec(FAT-
2 XENIXroot 39 Plan 9 82 Linux swap / So c4 DRDOS/sec(FAT-
3 XENIXusr 3c PartitionMagic 83 Linux c6 DRDOS/sec (FAT-
4 FAT16<32M 40 Venix 80286 84 OS/2 hidden C: c7 Syrinx
5 Extended 41 PPC PReP Boot 85 Linux extended da Non-FS data
6 FAT16 42 SFS 86 NTFS volume set db CP/M / CTOS /.
7 HPFS/NTFS 4d QNX4.x 87 NTFS volume set de DellUtility
8 AIX 4e QNX4.x 2nd part 88 Linux plaintext df BootIt
9 AIXbootable 4f QNX4.x 3rd part 8e Linux LVM e1 DOS access
a OS/2Boot Manag 50 OnTrack DM 93 Amoeba e3 DOS R/O
b W95FAT32 51 OnTrack DM6 Aux 94 Amoeba BBT e4 SpeedStor
c W95FAT32 (LBA) 52 CP/M 9f BSD/OS eb BeOS fs
e W95FAT16 (LBA) 53 OnTrack DM6 Aux a0 IBM Thinkpad hi ee EFI GPT
f W95Ext'd (LBA) 54 OnTrackDM6 a5 FreeBSD ef EFI (FAT-12/16/
10 OPUS 55 EZ-Drive a6 OpenBSD f0 Linux/PA-RISC b
11 Hidden FAT12 56 Golden Bow a7 NeXTSTEP f1 SpeedStor
12 Compaq diagnost 5c PriamEdisk a8 Darwin UFS f4 SpeedStor
14 Hidden FAT16 <3 61 SpeedStor a9 NetBSD f2 DOS secondary
16 Hidden FAT16 63 GNU HURD or Sys ab Darwin boot fb VMware VMFS
17 Hidden HPFS/NTF 64 NovellNetware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 65 Novell Netware b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 70 DiskSecureMult bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 75 PC/IX be Solaris boot ff BBT

Command (m for help): t #更改分区的系统ID
Selected partition 1 #选择第一个分区
Hex code (type L to list codes): 8e #默认是linux格式，更改为Linux LVM
Changed system type of partition 1 to 8e(Linux LVM)

Command (m for help): p #在屏幕打印出所有的分区

Disk /dev/sdb: 2040.1 GB, 2040109137920bytes
255 heads, 63 sectors/track, 248029cylinders
Units = cylinders of 16065 * 512 = 8225280bytes

Device Boot Start End Blocks Id System
/dev/sdb1 1 248029 1992292911 8e LinuxLVM

Command (m for help): w #把当前配置信息写入硬盘并退出
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

[root@mail ~]# fdisk /dev/sdc #对第三块硬盘进行分区
Device contains neither a valid DOSpartition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes willremain in memory only,
until you decide to write them. After that,of course, the previous
content won't be recoverable.

The number of cylinders for this disk isset to 248029.
There is nothing wrong with that, but thisis larger than 1024,
and could in certain setups cause problemswith:
1) software that runs at boot time (e.g.,old versions of LILO)
2) booting and partitioning software fromother OSs
(e.g., DOS FDISK, OS/2 FDISK)
Warning: invalid flag 0x0000 of partitiontable 4 will be corrected by w(rite)

Command (m for help): m #列出所有帮助信息
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibilityflag
d delete a partition
l list known partition types
m print this menu
n add a new partition
o create a new empty DOSpartition table
p print the partition table
q quit without saving changes
s create a new empty Sundisklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (expertsonly)

Command (m for help): n #创建新分区
Command action
e extended
p primary partition (1-4)
p #创建主分区
Partition number (1-4): 1 #创建第一块主分区
First cylinder (1-248029, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK(1-248029, default 248029):
Using default value 248029

Command (m for help): t #更改分区的系统ID
Selected partition 1 #选择第一个分区
Hex code (type L to list codes): 8e #默认是linux格式，更改为Linux LVM
Changed system type of partition 1 to 8e(Linux LVM)

Command (m for help): w #把当前配置信息写入硬盘并退出
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

[root@mail ~]# fdisk /dev/sdd #对第四块硬盘进行分区
Device contains neither a valid DOSpartition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes willremain in memory only,
until you decide to write them. After that,of course, the previous
content won't be recoverable.

The number of cylinders for this disk isset to 191145.
There is nothing wrong with that, but thisis larger than 1024,
and could in certain setups cause problemswith:
1) software that runs at boot time (e.g.,old versions of LILO)
2) booting and partitioning software fromother OSs
(e.g., DOS FDISK, OS/2 FDISK)
Warning: invalid flag 0x0000 of partitiontable 4 will be corrected by w(rite)

Command (m for help): n #创建分区
Command action
e extended
p primary partition (1-4)
p #创建主分区
Partition number (1-4): 1 #创建第一块主分区
First cylinder (1-191145, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK(1-191145, default 191145):
Using default value 191145

Command (m for help): t #更改分区的系统ID
Selected partition 1 #选择第一个分区
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e(Linux LVM)

Command (m for help): w #把当前配置信息写入硬盘并退出
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

-------------------------------------------- 以下是创建LV部分 -------------------------------------------------

[root@mail ~]# ls /dev/sd* #查看当前系统有多少分区，可以看到sdb，sdc，sdd这三块硬盘都是分成一个分区
/dev/sda /dev/sda1 /dev/sda2 /dev/sda3 /dev/sdb /dev/sdb1 /dev/sdc /dev/sdc1 /dev/sdd /dev/sdd1

[root@mail ~]# pvcreate /dev/sdb1 #sdb1转换成physical volume【pv就是物理卷的意思】
Physical volume "/dev/sdb1" successfully created
[root@mail ~]# pvcreate /dev/sdc1 #sdc1转换成physical volume
Physical volume "/dev/sdc1" successfully created
[root@mail ~]# pvcreate /dev/sdd1 #sdd1转换成physical volume
Physical volume "/dev/sdd1" successfully created
[root@mail ~]# pvs #显示当前系统所有的物理卷physical volume
PV VG Fmt Attr PSize PFree
/dev/sda1 VolGroup_ID_20054 lvm2a- 9.53G 9.53G
/dev/sda3 VolGroup_ID_20054 lvm2a- 590.25G 54.50G
/dev/sdb1 lvm2 -- 1.86T 1.86T
/dev/sdc1 lvm2-- 1.86T 1.86T
/dev/sdd1 lvm2-- 1.43T 1.43T
[root@mail~]# vgcreate vg_de /dev/ sdb1 #创建卷组vg_de，并把sdb1加进来
Nophysical volume label read from /dev/sdb1
Physical volume "/dev/sdb1" successfully created
Volume group "vg_de" successfully created
[root@mail ~]# vgextend vg_de /dev/sdc1 #扩展卷组，把sdc1加进来
Nophysical volume label read from /dev/sdc1
Physical volume "/dev/sdc1" successfully created
Volume group "vg_de" successfully extended
[root@mail ~]# vgextend vg_de /dev/sdd1 #扩展卷组，把sdd1加进来
Nophysical volume label read from /dev/sdd1
Physical volume "/dev/sdd1" successfully created
Volume group "vg_de" successfully extended
[root@mail ~]# vgs #显示系统所有卷组
VG #PV #LV #SNAttr VSize VFree
VolGroup_ID_20054 2 6 0wz--n- 599.78G 64.03G
vg_de 3 0 0wz--n- 5.14T 5.14T

[root@mail ~]# lvcreate -L 5.14T -n lv_devg_de #创建逻辑卷lv_de，并把卷组vg _de的空间资源全部分给其使用
Rounding up size to full physical extent 5.14 TB
Logical volume "lv_de" created
[root@mail ~]# lvs #显示系统所有逻辑卷
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
LogVol0 VolGroup_ID_20054-wi-ao 4.00G
LogVol1 VolGroup_ID_20054-wi-ao 55.94G
LogVol2 VolGroup_ID_20054-wi-ao 9.88G
LogVol4 VolGroup_ID_20054-wi-ao 74.38G
LogVol5 VolGroup_ID_20054-wi-ao 268.00G
LogVolHome VolGroup_ID_20054 -wi-ao 123.56G
lv_de vg_de -wi-a- 5.14T

[root@mail ~]# mkfs -t ext3 /dev/vg_de/lv_de #把lv_de格式化为ext3格式
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
689881088 inodes, 1379759104 blocks
68987955 blocks (5.00%) reserved for thesuper user
First data block=0
Maximum filesystem blocks=4294967296
42107 block groups
32768 blocks per group, 32768 fragments pergroup
16384 inodes per group
Superblock backups stored on blocks:
32768,98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000,7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
102400000,214990848, 512000000, 550731776, 644972544

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

This filesystem will be automaticallychecked every 25 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.

[root@mail ~]# mount /dev/vg_de/lv_de /local/ #把lv_de逻辑卷挂载到 /local/ 使用

[root@mail ~]# df –h #以易看懂的方式显示当前所有挂载点空余空间，df是disk free的简称
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/VolGroup_ID_20054-LogVol1
55G 465M 51G 1% /
/dev/mapper/VolGroup_ID_20054-LogVol2
9.6G 151M 9.0G 2% /tmp
/dev/mapper/VolGroup_ID_20054-LogVol4
73G 243M 69G 1% /var
/dev/mapper/VolGroup_ID_20054-LogVol5
260G 2.1G 245G 1% /usr
/dev/sda2 190M 16M 165M 9% /boot
tmpfs 7.9G 0 7.9G 0% /dev/shm
/dev/mapper/VolGroup_ID_20054-LogVolHome
122G 219M 116G 1% /home
/dev/mapper/vg_de-lv_de
5.1T 188M 4.9T 1% /local

[root@mail ~]# vi /etc/fstab #编辑磁盘开机挂载文件，使lv_de逻辑卷挂载到 /local/ 这个效果永久生效。对于Linux而言，一切没有写入文件的操作，关机重启则无效
/dev/VolGroup_ID_20054/LogVol1 / ext3 defaults 1 1
/dev/VolGroup_ID_20054/LogVol2 /tmp ext3 defaults 1 2
/dev/VolGroup_ID_20054/LogVol4 /var ext3 defaults 1 2
/dev/VolGroup_ID_20054/LogVol5 /usr ext3 defaults 1 2

LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup_ID_20054/LogVol0 swap swap defaults 0 0
/dev/VolGroup_ID_20054/LogVolHome /home ext3 defaults 1 2
/dev/vg_de/lv_de /local ext3 defaults 0 2

[root@mail ~]# reboot
-----------
题外话：作者本人当时编辑fstab文件的时候，加载LV磁盘的有些地方没注意写错了，导致系统一重启就找不到LV磁盘，进入到了单用户维护模式，而此时 / 是只读的，根本没办法把有错的地方改过来。后来发现可以用 mount -n -o remount,rw / 的命令来重新挂载 / ，然后就可以修改文件啦，这个命令很有用，无论你是因为什么原因进到这样的一个维护模式，都可以用这样的命令，然后获取对磁盘的写入权限。