LVM扩展学习日志

lvm是逻辑卷管理的简称，它将一个或多个物理硬盘分区(PV)组成一个逻辑硬盘(VG)来使用,  然后从这个VG中划分出逻辑分区（LV), 以上概念是我理解的东西，可能和书上的不一样。

以下所有命令都是在CENTOS6.5上进行操作的

1：对磁盘进行分区

使用fdisk对磁盘进行分区。注意分区的格式，LVM对应的是8e， 创建完成后记得重启电脑。

Command (m for help): p

Disk /dev/vda: 85.9 GB,  bytes
 heads,  sectors/track,  cylinders
Units = cylinders of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk identifier: 0x00035557

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *                              Linux
Partition  does not end on cylinder boundary.
/dev/vda2                          8e  Linux LVM
Partition  does not end on cylinder boundary.
/dev/vda3                        8e  Linux LVM

2: 创建PV

pvcreate使用磁盘分区来创建PV

[root@centos-vm- ~]# pvcreate  /dev/vda3
  Physical volume "/dev/vda3" successfully created
[root@centos-vm- ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/vda2
  VG Name               vg_centos6
  PV Size               19.51 GiB / not usable 3.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE
  Free PE
  Allocated PE
  PV UUID               YzeBUf-Pxvv-5fct-I5Mz-6NDg-fIsI-Zjv7RT

  "/dev/vda3" is a new physical volume of "60.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/vda3
  VG Name
  PV Size               60.00 GiB
  Allocatable           NO
  PE Size
  Total PE
  Free PE
  Allocated PE
  PV UUID               5B99Bs-waNc-QSnO-YWu5-XdMH-xRB6-epWFzJ

3：创建VG

如果已经有VG的话那么不需要创建新的VG，直接把PV添加到VG中就可以了。

[root@centos-vm- ~]# vgdisplay
  --- Volume group ---
  VG Name               vg_centos6
  System ID
  Format                lvm2
  Metadata Areas
  Metadata Sequence No
  VG Access             read/write
  VG Status             resizable
  MAX LV
  Cur LV
  Open LV
  Max PV
  Cur PV
  Act PV
  VG Size               19.51 GiB
  PE Size               4.00 MiB
  Total PE
  Alloc PE / Size        / 19.51 GiB
  Free  PE / Size        /
  VG UUID               wyjVpO-L0jl-ckoF-SU4K-JTNd-p3Nb-YwMgO9

[root@centos-vm- ~]# vgcreate  vg_centos6_1 /dev/vda3

创建vg的使用后面可以跟多个PV（pv和磁盘分区同名）。

如果想把PV添加到已经存在的vg中使用下面的命令：

[root@centos-vm- ~]# vgextend vg_centos6 /dev/vda3
  Volume group "vg_centos6" successfully extended

3：创建LV

显示当前的lv

[root@centos-vm- ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/vg_centos6/lv_root
  LV Name                lv_root
  VG Name                vg_centos6
  LV UUID                4QMRdu-2JYb-a7BM-OSw9-nRrz-nGmV-Z80yeO
  LV Write Access        read/write
  LV Creation host, time centos6., -- :: +
  LV Status              available
  # open
  LV Size                17.54 GiB
  Current LE
  Segments
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to
  Block device           :

  --- Logical volume ---
  LV Path                /dev/vg_centos6/lv_swap
  LV Name                lv_swap
  VG Name                vg_centos6
  LV UUID                8awkxq-UpsI-mPml-GTrx-tWDu-MkhI-tA3OhS
  LV Write Access        read/write
  LV Creation host, time centos6., -- :: +
  LV Status              available
  # open
  LV Size                1.97 GiB
  Current LE
  Segments
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to
  Block device           :

创建一个新的LV

 lvcreate -L  10G -n data  vg_centos6

-L指定分区的大小，-n指定分区名，vg_centos6是vg名字

扩展LV，有时不想添加新的分区，那么可以扩展该LV

[root@centos-vm- ~]# lvextend -L +18G   /dev/vg_centos6/lv_root
  Extending logical volume lv_root to 77.00 GiB
  Logical volume lv_root successfully resized
[root@centos-vm- ~]# resize2fs  /dev/vg_centos6/lv_root
resize2fs 1.41. (-May-)
Filesystem at /dev/vg_centos6/lv_root is mounted on /; on-line resizing required
old desc_blocks = , new_desc_blocks =
Performing an on-line resize of /dev/vg_centos6/lv_root to  (4k) blocks.
The filesystem on /dev/vg_centos6/lv_root is now  blocks long.

[root@centos-vm- ~]# df -h
Filesystem                      Size  Used Avail Use% Mounted on
/dev/mapper/vg_centos6-lv_root   76G  .9G   71G   % /
tmpfs                           940M   72K  940M   % /dev/shm
/dev/vda1                       485M   40M  421M   % /boot

注意-L的参数是 +18G，在扩展LV的容量后需要resize2fs是容量生效

4： 格式化文件系统

如果生成了新的LV,那么需要对分区进行文件系统格式化

mkfs.ext4   /dev/vg_centos6/lv_root

然后mout,最后修改/etc/fstab.