3、LVM基础配置试验
LVM配置主要是通过LVM命令台和工具命令来实现的。通过lvm的帮助功能，我们能看到对lv、vg和pv的管理命令。
[root@SimpleLinux ~]# lvm
lvm> help
Available lvm commands:
Use 'lvm help <command>' for more information
dumpconfigDump active configuration
formatsList available metadata formats
helpDisplay help for commands
lvchangeChange the attributes of logical volume(s)
lvconvertChange logical volume layout
lvcreateCreate a logical volume
lvdisplayDisplay information about a logical volume
lvextendAdd space to a logical volume
lvmchangeWith the device mapper, this is obsolete and does nothing.
lvmdiskscanList devices that may be used as physical volumes
lvmsadcCollect activity data
lvmsarCreate activity report
lvreduceReduce the size of a logical volume
lvremoveRemove logical volume(s) from the system
lvrenameRename a logical volume
lvresizeResize a logical volume
lvsDisplay information about logical volumes
lvscanList all logical volumes in all volume groups
pvchangeChange attributes of physical volume(s)
pvresizeResize physical volume(s)
pvckCheck the consistency of physical volume(s)
pvcreateInitialize physical volume(s) for use by LVM
pvdataDisplay the on-disk metadata for physical volume(s)
pvdisplayDisplay various attributes of physical volume(s)
pvmoveMove extents from one physical volume to another
pvremoveRemove LVM label(s) from physical volume(s)
pvsDisplay information about physical volumes
pvscanList all physical volumes
segtypesList available segment types
vgcfgbackupBackup volume group configuration(s)
vgcfgrestoreRestore volume group configuration
vgchangeChange volume group attributes
vgckCheck the consistency of volume group(s)
vgconvertChange volume group metadata format
vgcreateCreate a volume group
vgdisplayDisplay volume group information
vgexportUnregister volume group(s) from the system
vgextendAdd physical volumes to a volume group
vgimportRegister exported volume group with system
vgmergeMerge volume groups
vgmknodesCreate the special files for volume group devices in /dev
vgreduceRemove physical volume(s) from a volume group
vgremoveRemove volume group(s)
vgrenameRename a volume group
vgsDisplay information about volume groups
vgscanSearch for all volume groups
vgsplitMove physical volumes into a new or existing volume group
versionDisplay software and driver version information
lvm>
注意：lvm虽然提供了控制台接口，但是直接敲命令Linux也是支持的。
[root@SimpleLinux /]# pvscan
No matching physical volumes found
虽然命令行很多，但是基本上lvm的命令还有很强的规律性。lv开头的都是对logical volume的操作，vg是对logical volume group，而pv是针对phyiscal volume的操作。
创建使用LVM，我们需要从最底层的PV进行构建管理。首先，我们需要创建最底层的Phsical Volume。
--pvcreate命令创建PV
[root@SimpleLinux /]# pvcreate /dev/sdb1
Physical volume "/dev/sdb1" successfully created
--显示信息
[root@SimpleLinux /]# pvscan
PV /dev/sdb1lvm2 [8.00 GB]
Total: 1 [8.00 GB] / in use: 0 [0] / in no VG: 1 [8.00 GB]
[root@SimpleLinux /]# pvcreate /dev/sdc1
Physical volume "/dev/sdc1" successfully created
[root@SimpleLinux /]# pvcreate /dev/sdc2
Physical volume "/dev/sdc2" successfully created
[root@SimpleLinux /]# pvcreate /dev/sdc3
Physical volume "/dev/sdc3" successfully created
[root@SimpleLinux /]# pvcreate /dev/sdc5
Physical volume "/dev/sdc5" successfully created
[root@SimpleLinux /]# pvcreate /dev/sdc6
Physical volume "/dev/sdc6" successfully created
[root@SimpleLinux /]# pvscan
PV /dev/sdb1lvm2 [8.00 GB]
PV /dev/sdc1lvm2 [1.87 GB]
PV /dev/sdc2lvm2 [1.87 GB]
PV /dev/sdc3lvm2 [1.87 GB]
PV /dev/sdc5lvm2 [1.87 GB]
PV /dev/sdc6lvm2 [3.07 GB]
Total: 6 [18.55 GB] / in use: 0 [0] / in no VG: 6 [18.55 GB]
[root@SimpleLinux /]#
使用pvs可以显示出当前可用的Physical Volume情况。
[root@SimpleLinux /]# pvs
PVVGFmtAttr PSize PFree
/dev/sdb1lvm2 --8.00G 8.00G
/dev/sdc1lvm2 --1.87G 1.87G
/dev/sdc2lvm2 --1.87G 1.87G
/dev/sdc3lvm2 --1.87G 1.87G
/dev/sdc5lvm2 --1.87G 1.87G
/dev/sdc6lvm2 --3.07G 3.07G
底层PV创建完成之后，就可以创建Logical Volume Group。
[root@SimpleLinux /]# vgcreate VolGrp01 /dev/sdb1 /dev/sdc1
Volume group "VolGrp01" successfully created
[root@SimpleLinux /]# vgs
VG#PV #LV #SN AttrVSize VFree
VolGrp01200 wz--n- 9.86G 9.86G
[root@SimpleLinux /]# vgcreate VolGrp02 /dev/sdc2 /dev/sdc3
Volume group "VolGrp02" successfully created
[root@SimpleLinux /]# vgs
VG#PV #LV #SN AttrVSize VFree
VolGrp01200 wz--n- 9.86G 9.86G
VolGrp02200 wz--n- 3.73G 3.73G
[root@SimpleLinux /]# vgdisplay
--- Volume group ---
VG NameVolGrp02
System ID
Formatlvm2
Metadata Areas2
Metadata Sequence No1
VG Accessread/write
VG Statusresizable
MAX LV0
Cur LV0
Open LV0
Max PV0
Cur PV2
Act PV2
VG Size3.73 GB
PE Size4.00 MB
Total PE956
Alloc PE / Size0 / 0
FreePE / Size956 / 3.73 GB
VG UUIDgfB8C3-80Ym-eEO5-L12p-8vdS-GWxy-t1QgWx
--- Volume group ---
VG NameVolGrp01
System ID
Formatlvm2
Metadata Areas2
Metadata Sequence No1
VG Accessread/write
VG Statusresizable
MAX LV0
Cur LV0
Open LV0
Max PV0
Cur PV2
Act PV2
VG Size9.86 GB
PE Size4.00 MB
Total PE2525
Alloc PE / Size0 / 0
FreePE / Size2525 / 9.86 GB
VG UUIDSDx5QB-7t14-RFrk-FUkK-1M43-4sNe-LFljgm
创建了两个LVG对象，每个LVG中包括两个分区PV。VolGrp01和VolGrp02为我们创建出的存储池。在其中，我们可以创建控制大小的Logical Volume。
[root@SimpleLinux /]# lvcreate -n lv1 -L +100M VolGrp01
Logical volume "lv1" created
[root@SimpleLinux /]# lvs
LVVGAttrLSizeOrigin Snap%Move Log Copy%Convert
lv1VolGrp01 -wi-a- 100.00M
注意下lvcreate参数，-n表示创建lv的名称，-L表示补充大小。最后一个参数表示在哪个LVG中进行分配。这个分配动作是动态过程。创建了lv1之后，就可以将其作为一个存储进行单独使用。
最后，我们可以格式化lv1，进行分配。
[root@SimpleLinux ~]# mkfs -t ext3 /dev/VolGrp01/lv1
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
25688 inodes, 102400 blocks
5120 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
13 block groups
8192 blocks per group, 8192 fragments per group
1976 inodes per group
Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729
Writing inode tables: done
Creating journal (4096 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.
最后，我们可以加载mount到一个目录上。
[root@SimpleLinux /]# mkdir /voltest01
[root@SimpleLinux /]# ls -l | grep vol
drwxr-xr-x2 rootroot4096 Oct9 12:30 voltest01
[root@SimpleLinux VolGrp01]# mount /dev/VolGrp01/lv1 /voltest01
[root@SimpleLinux VolGrp01]# df -h
FilesystemSizeUsed Avail Use% Mounted on
/dev/sda148G11G35G23% /
tmpfs449M0449M0% /dev/shm
/dev/mapper/VolGrp01-lv1
97M1.6M91M2% /voltest01
使用dd命令，测试/voltest01目录的可用性。
[root@SimpleLinux VolGrp01]# cd /voltest01/
[root@SimpleLinux voltest01]# ls -l
total 12
drwx------ 2 root root 12288 Oct9 12:34 lost+found
[root@SimpleLinux voltest01]# dd if=/dev/zero f=/voltest01/res bs=1024 count=1000
1000+0 records in
1000+0 records out
1024000 bytes (1.0 MB) copied, 0.00376333 seconds, 272 MB/s
[root@SimpleLinux voltest01]# ls -l
total 1017
drwx------ 2 root root12288 Oct9 12:34 lost+found
-rw-r--r-- 1 root root 1024000 Oct9 12:36 res
添加目录和加载成功。最后一个问题是，我们加载mount是手工过程，需要修改/etc/fstab，来实现自动添加。在下次reboot系统时候，就可以实现自动加载Logical Volume了。
[root@SimpleLinux ~]# blkid
/dev/sda2: TYPE="swap" LABEL="SWAP-sda2"
/dev/sda1: LABEL="/" UUID="36e661fb-e9ef-4583-8fc9-422b00009016" TYPE="ext3" SEC_TYPE="ext2"
/dev/cdrom: LABEL="RHEL/5.3 i386 DVD" TYPE="iso9660"
/dev/VolGrp01/lv1: UUID="5e007a89-326d-4a71-9744-8cd7d36a90a7" SEC_TYPE="ext2" TYPE="ext3"
/dev/mapper/VolGrp01-lv1: UUID="5e007a89-326d-4a71-9744-8cd7d36a90a7" SEC_TYPE="ext2" TYPE="ext3"
[root@SimpleLinux ~]# cat /etc/fstab
LABEL=//ext3defaults1 1
tmpfs/dev/shmtmpfsdefaults0 0
devpts/dev/ptsdevptsgid=5,mode=6200 0
sysfs/syssysfsdefaults0 0
proc/procprocdefaults0 0
UUID="5e007a89-326d-4a71-9744-8cd7d36a90a7"/voltest01ext3defaults1 1
LABEL=SWAP-sda2swapswapdefaults0 0
重新reboot之后，依然加载成功。
[root@SimpleLinux ~]# df -h
FilesystemSizeUsed Avail Use% Mounted on
/dev/sda148G11G35G23% /
tmpfs449M0449M0% /dev/shm
/dev/mapper/VolGrp01-lv1
97M5.6M87M7% /voltest01
下面我们测试一下LVM的调整功能。