Extended Linux system root partition

Environment: VMware Virtual Machine Red Hat 6.5

Technology: Logical Volume Manager (LVM)

Description: In order to do this experiment, make sure that the Linux system has sufficient disk space, if you need to add disk space is insufficient disk. The method of this document expands Linux system root partition is done in a virtual environment, the same applies in a production environment.

Specific steps:

1. Check disk space

[root@localhost ~]# df -h
#查看磁盘空间，根分区的大小是18G，已经用了43%。
Filesystem                    Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root   18G  7.0G  9.5G  43% /
tmpfs                         2.0G   76K  2.0G   1% /dev/shm
/dev/sda1                     485M   40M  421M   9% /boot
/dev/sr0                      3.6G  3.6G     0 100% /media/cdrom

2. Create Partition

[root@localhost ~]# fdisk -l

Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00083529

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              64        2611    20458496   8e  Linux LVM
#/dev/sdb盘还有足够的空间
Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/VolGroup-lv_root: 18.8 GB, 18798870528 bytes
255 heads, 63 sectors/track, 2285 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/VolGroup-lv_swap: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


[root@localhost ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xac7c929b.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): p

Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xac7c929b

   Device Boot      Start         End      Blocks   Id  System

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1#分区号
First cylinder (1-2610, default 1):  #回车用默认的
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): #回车用默认的
Using default value 2610

Command (m for help): t #改变类型
Selected partition 1
Hex code (type L to list codes): 8e #LVM的分区代码
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): p

Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xac7c929b

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        2610    20964793+  8e  Linux LVM

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# partprobe
#将磁盘分区表变化信息通知内核，请求操作系统重新加载分区表，有些小报错不要紧。
Warning: WARNING: the kernel failed to re-read the partition table on /dev/sda (Device or resource busy).  As a result, it may not reflect all of your changes until after reboot.
Warning: WARNING: the kernel failed to re-read the partition table on /dev/sdb (Device or resource busy).  As a result, it may not reflect all of your changes until after reboot.
Warning: Unable to open /dev/sr0 read-write (Read-only file system).  /dev/sr0 has been opened read-only.
Warning: Unable to open /dev/sr0 read-write (Read-only file system).  /dev/sr0 has been opened read-only.
Error: Invalid partition table - recursive partition on /dev/sr0.

3. Create a physical volume

[root@localhost ~]# fdisk -l

Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00083529

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              64        2611    20458496   8e  Linux LVM

Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xac7c929b

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        2610    20964793+  8e  Linux LVM

Disk /dev/mapper/VolGroup-lv_root: 18.8 GB, 18798870528 bytes
255 heads, 63 sectors/track, 2285 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/VolGroup-lv_swap: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


[root@localhost ~]# pvcreate /dev/sdb1
#由fdisk -l查到LVM卷是/dev/sdb1，所以用/dev/sdb1来创建物理卷。
  Physical volume "/dev/sdb1" successfully created

4. The extended volume group

[root@localhost ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               VolGroup
  PV Size               19.51 GiB / not usable 3.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              4994
  Free PE               0
  Allocated PE          4994
  PV UUID               qkBdcn-RQaR-ZliO-Ja2S-RhMC-stw8-CO213I
   
  "/dev/sdb1" is a new physical volume of "19.99 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb1
  VG Name               
  PV Size               19.99 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               H7tDqG-6AZv-yBSA-U0ov-Ni0y-dlPA-kAA83i
   
[root@localhost ~]# vgextend VolGroup /dev/sdb1
  Volume group "VolGroup" successfully extended
You have new mail in /var/spool/mail/root
[root@localhost ~]# vgdisplay
  --- Volume group ---
  VG Name               VolGroup
  System ID             
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  4
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               39.50 GiB
  PE Size               4.00 MiB
  Total PE              10112
  Alloc PE / Size       4994 / 19.51 GiB
  Free  PE / Size       5118 / 19.99 GiB
  VG UUID               dc0vI9-KzGu-4S59-A1xv-NM4Y-rYBF-3jDNRn
   

5. Logical Volume expansion

[root@localhost ~]# lvextend -l +100%free /dev/mapper/VolGroup-lv_root
#free也可以大写FREE
  Extending logical volume lv_root to 37.50 GiB
  Logical volume lv_root successfully resized
[root@localhost ~]# blkid /dev/mapper/VolGroup-lv_root
#查看分区文件系统类型
/dev/mapper/VolGroup-lv_root: UUID="972fdddd-ddb8-469f-a342-e075eaeabeb2" TYPE="ext4" 
[root@localhost ~]# e2fsck -f /dev/mapper/VolGroup-lv_root
#e2fsck -f检查分区
e2fsck 1.41.12 (17-May-2010)
/dev/mapper/VolGroup-lv_root is mounted.
e2fsck: Cannot continue, aborting.


[root@localhost ~]# resize2fs /dev/mapper/VolGroup-lv_root
#如果分区是xfs系统，则用xfs_growfs命令对文件系统进行扩展
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/VolGroup-lv_root is mounted on /; on-line resizing required
old desc_blocks = 2, new_desc_blocks = 3
Performing an on-line resize of /dev/mapper/VolGroup-lv_root to 9830400 (4k) blocks.
The filesystem on /dev/mapper/VolGroup-lv_root is now 9830400 blocks long.

[root@localhost ~]# df -h
#查看磁盘空间，根分区已扩展到37G。
Filesystem                    Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root   37G  7.0G   29G  20% /
tmpfs                         2.0G  224K  2.0G   1% /dev/shm
/dev/sda1                     485M   40M  421M   9% /boot
/dev/sr0                      3.6G  3.6G     0 100% /media/cdrom