lvm卷组扩展过程

lvm卷组扩展过程

LVM相关概念和术语
LVM是建立在磁盘分区和文件系统之间的一个逻辑层，来为文件系统屏蔽下层磁盘分区布局，提供一个逻辑的盘卷，再在盘卷上来建立文件系统。LVM的结构如图1如示：
图1 LVM结构图
在上面的LVM结构图中，涉及到了很多LVM的相关术语，那么关于这些术语的详细说明如下：
物理卷（physical volume，PV）
物理卷就是指硬盘分区，也可以是整个硬盘或已创建的软RAID ，是LVM的基本存储设备，与普通物理存储介质的区别是该设备包含有LVM相关的管理参数。
卷组（volume group，VG）
卷组是由一个或多个物理卷所组成的存储池，在卷组上能创建一个或多个“LVM分区”（逻辑卷）。
逻辑卷（logical volume，LV）
LVM的逻辑卷类似于非LVM系统中的硬盘分区，它建立在卷组之上，是一个标准的块设备，在逻辑卷之上可以建立文件系统。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，那么在地球上划分一个区域并标记为亚洲，则亚洲就相当于一个LV。

操作情况：服务器有3块 480GB的ssd，其中一块用lvm卷方式安装了系统。由于系统空间不足，现在要把另外二块ssd也组合在一起。
下面是实际操作过程。

1、首先确认硬盘情况
[root@localhost ~]# fdisk -l

Disk /dev/sda: 480.1 GB, 480103981056 bytes
255 heads, 63 sectors/track, 58369 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x4588b405

Device Boot Start End Blocks Id System
/dev/sda1 1 132 1060256+ 83 Linux
Partition 1 does not end on cylinder boundary.
Partition 1 does not start on physical sector boundary.
/dev/sda2 132 58369 467788704+ 8e Linux LVM

Disk /dev/sdb: 480.1 GB, 480103981056 bytes
255 heads, 63 sectors/track, 58369 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x40f77e99

Device Boot Start End Blocks Id System
/dev/sdb1 * 1 58369 468848961 7 HPFS/NTFS
Partition 1 does not start on physical sector boundary.

Disk /dev/sdc: 480.1 GB, 480103981056 bytes
255 heads, 63 sectors/track, 58369 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x986784e7

Device Boot Start End Blocks Id System
/dev/sdc1 * 1 58369 468848961 7 HPFS/NTFS
Partition 1 does not start on physical sector boundary.

可以看到服务器中有三块硬盘。/dev/sda其中的/dev/sdb ,/dev/sdc这二块ssd就是我们要添加到LVM卷中的目标。

2、用parted进行分区

先将/dev/sdb分区
[root@localhost ~]# parted /dev/sdb
GNU Parted 2.1
使用 /dev/sdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p
Model: ATA INTEL SSDSC2KG48 (scsi)
Disk /dev/sdb: 480GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos

Number Start End Size Type File system 标志
1 32.3kB 480GB 480GB primary ntfs 启动

(parted) rm 1
(parted) mklabel gpt
警告: The existing disk label on /dev/sdb will be destroyed and all data on this disk will be lost. Do you want to continue?
是/Yes/否/No? yes
(parted) mapart ext4 0% 100%
(parted) q
信息: You may need to update /etc/fstab.

将/dev/sdc分区
[root@localhost ~]# parted /dev/sdc
GNU Parted 2.1
使用 /dev/sdc
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p
Model: ATA INTEL SSDSC2KG48 (scsi)
Disk /dev/sdc: 480GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos

Number Start End Size Type File system 标志
1 32.3kB 480GB 480GB primary ntfs 启动

(parted) rm 1
(parted) mklabel gpt
警告: The existing disk label on /dev/sdc will be destroyed and all data on this disk will be lost. Do you want to continue?
是/Yes/否/No? yes
(parted) mkpart ext4 0% 100%
(parted) q
信息: You may need to update /etc/fstab.

3、查看并扩展LVM卷，其中VG1是要扩展的VG卷
[root@localhost ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/loop1 cinder-volumes lvm2 a-- 20.60g 20.60g
/dev/mapper/Crypt_Disk VG1 lvm2 a-- 446.11g 1.11g
[root@localhost ~]# pvcreate /dev/sdb1
Physical volume "/dev/sdb1" successfully created
[root@localhost ~]# pvcreate /dev/sdc1
Physical volume "/dev/sdc1" successfully created
[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
VG1 1 1 0 wz--n- 446.11g 1.11g
cinder-volumes 1 0 0 wz--n- 20.60g 20.60g

扩展VG卷组
[root@localhost ~]# vgextend VG1 /dev/sdb1
Volume group "VG1" successfully extended
[root@localhost ~]# vgextend VG1 /dev/sdc1
Volume group "VG1" successfully extended
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
lv_root VG1 -wi-ao---- 445.00g

扩展LV卷组，增加800G的容量（不全部用掉，保留一点空间）
[root@localhost ~]# lvextend -L +800G /dev/VG1/lv_root
Extending logical volume lv_root to 1.22 TiB
Logical volume lv_root successfully resized

查看lv_root大小，439G，没有变大。
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VG1-lv_root
439G 20G 396G 5% /
tmpfs 79G 4.0K 79G 1% /dev/shm
/dev/sda1 1020M 97M 871M 11% /boot

4、还需要最后一个命令，扩展文件系统
[root@localhost ~]# resize2fs -p -F /dev/VG1/lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/VG1/lv_root is mounted on /; on-line resizing required
old desc_blocks = 28, new_desc_blocks = 78
Performing an on-line resize of /dev/VG1/lv_root to 326369280 (4k) blocks.
The filesystem on /dev/VG1/lv_root is now 326369280 blocks long.
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VG1-lv_root
1.2T 20G 1.2T 2% /
tmpfs 79G 4.0K 79G 1% /dev/shm
/dev/sda1 1020M 97M 871M 11% /boot

扩展成功。