关于Linux 的逻辑卷知识，以前前接触过一些，今天再次温习下，主要是演练下 LVM
的创建过程及维护命令，LVM 理论部分和虚拟机增加硬盘部分略。
--1 环境准备
虚拟机：Red Hat Enterprise Linux Server release 5.5
增加两块 IDE 硬盘，一块为 2GB，另一块为 1GB。
--2 查看新增硬盘情况
Disk /dev/hda: 19.3 GB, 19327352832 bytes
255 heads, 63 sectors/track, 2349 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/hda1 * 1 13 104391 83 Linux
/dev/hda2 14 144 1052257+ 82 Linux swap / Solaris
/dev/hda3 145 2349 17711662+ 83 Linux
Disk /dev/hdb: 2147 MB, 2147483648 bytes
16 heads, 63 sectors/track, 4161 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Device Boot Start End Blocks Id System
/dev/hdb1 1 1985 1000408+ 83 Linux
/dev/hdb2 1986 4161 1096704 83 Linux
Disk /dev/hdd: 1073 MB, 1073741824 bytes
16 heads, 63 sectors/track, 2080 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Device Boot Start End Blocks Id System
/dev/hdd1 1 2080 1048288+ 83 Linux
备注： /dev/hdb， /dev/hdd 就是新增的盘， /dev/hdb 为 2147 MB，/dev/hdd
为 1073 MB。
--3 创建PV ( pvcreat )
[root@pgb ~]# pvcreate /dev/hdb1 /dev/hdd1
/dev/cdrom: open failed: Read-only file system
Attempt to close device '/dev/cdrom' which is not open.
Physical volume "/dev/hdb1" successfully created
/dev/cdrom: open failed: Read-only file system
Attempt to close device '/dev/cdrom' which is not open.
Physical volume "/dev/hdd1" successfully created
备注：在创建 VG 之前，首先要将物理设备标识成 LVM 可识别的物理设备，另外
pvcreate 命令会清除设备上的所有数据。
--4 查看 PV 信息
[root@pgb ~]# pvscan
PV /dev/hdb1 lvm2 [976.96 MB]
PV /dev/hdd1 lvm2 [1023.72 MB]
Total: 2 [1.95 GB] / in use: 0 [0 ] / in no VG: 2 [1.95 GB]
备注：上面显示 /dev/hdb1， /dev/hdd1 已经创建成 PV 了。
--5 创建VG ( vgcreate )
[root@pgb ~]# vgcreate vg01_pgdata /dev/hdb1 /dev/hdd1
/dev/cdrom: open failed: Read-only file system
/dev/cdrom: open failed: Read-only file system
Attempt to close device '/dev/cdrom' which is not open.
/dev/cdrom: open failed: Read-only file system
Attempt to close device '/dev/cdrom' which is not open.
/dev/cdrom: open failed: Read-only file system
Attempt to close device '/dev/cdrom' which is not open.
Volume group "vg01_pgdata" successfully created
--6 显示 VG 信息
[root@pgb ~]# vgdisplay
--- Volume group ---
VG Name vg01_pgdata
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 1.95 GB
PE Size 4.00 MB
Total PE 499
Alloc PE / Size 0 / 0
Free PE / Size 499 / 1.95 GB
VG UUID B5pg8R-2AGm-6DEp-K7HK-TI1I-HC3h-gWx32m
备注: 逻辑卷 vg01_pgdata 创建成功，大小为 1.95 GB。
--7 创建LV
[root@pgb lvm]# lvcreate -L 1G -n lv_pgdata1 vg01_pgdata
Logical volume "lv_pgdata1" created
--8 扫描 lv 逻辑单元
[root@pgb lvm]# lvscan
ACTIVE '/dev/vg01_pgdata/lv_pgdata1' [1.00 GB] inherit
--9 查看LV信息
[root@pgb lvm]# lvdisplay /dev/vg01_pgdata/lv_pgdata1
--- Logical volume ---
LV Name /dev/vg01_pgdata/lv_pgdata1
VG Name vg01_pgdata
LV UUID pXsfbX-MAdM-6FQ5-cUz6-IKXC-hRJM-sNQ9yp
LV Write Access read/write
LV Status available
# open 0
LV Size 1.00 GB
Current LE 256
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
备注：LV创建成功，大小为 1 GB，接下来可以格式化并挂载 LV 了。
--10 格式化文件系统
[root@pgb lvm]# mkfs -t ext3 -c /dev/vg01_pgdata/lv_pgdata1
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
131072 inodes, 262144 blocks
13107 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=268435456
8 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376
Checking for bad blocks (read-only test): done
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 30 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
--11 目录挂载
[root@pgb lvm]# mkdir -p /database/pgdata1
[root@pgb lvm]# mount -t ext3 /dev/vg01_pgdata/lv_pgdata1 /database/pgdata1
[root@pgb lvm]# chown -R postgres:postgres /database/pgdata1
[root@pgb lvm]# df -hv
Filesystem Size Used Avail Use% Mounted on
/dev/hda3 17G 9.8G 5.8G 64% /
/dev/hda1 99M 18M 76M 20% /boot
tmpfs 217M 0 217M 0% /dev/shm
none 217M 104K 217M 1% /var/lib/xenstored
/dev/mapper/vg01_pgdata-lv_pgdata1
1008M 34M 924M 4% /database/pgdata1
备注：到了这步， LVM 配置成功，目录挂载成功。
--12 设置开机自动挂载
修改文件 /etc/fstab,增加以下行
/dev/vg01_pgdata/lv_pgdata1 /database/pgdata1 ext3 defaults 0 0
--13 再次查看 VG
[root@pgb lvm]# vgdisplay
--- Volume group ---
VG Name vg01_pgdata
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 2
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 2
Act PV 2
VG Size 1.95 GB
PE Size 4.00 MB
Total PE 499
Alloc PE / Size 256 / 1.00 GB
Free PE / Size 243 / 972.00 MB
VG UUID B5pg8R-2AGm-6DEp-K7HK-TI1I-HC3h-gWx32m
备注：分配了(Alloc PE) 1GB，还剩余 (Free PE) 972 MB。
--14 常见 LVM 命令
| 功能 |
PV |
VG |
LV |
| 搜索 |
pvscan |
vgscan |
lvscan |
| 建立 |
pvcreate |
vgcreate |
lvcreate |
| 列出 |
pvdisplay |
vgdisplay |
lvdisplay |
| 增加 |
|
vgextend |
lvextend |
| 减少 |
|
vgreduce |
lvreduce |
| 删除 |
|
vgremove |
lvremove |
转载http://francs3.blog.163.com/blog/static/40576727201212242741910/