lvm扩展根目录
1.lvm的基本概念
physical volume (PV)
通常是一快硬盘。相当于一个物理设备，磁盘空间物理卷PV。
volume group (VG)
相当于LVM的卷组，属于一个抽象下的组概念，一个VG可以包括多个PV。我的实操是我的VG下面，包含了PV(/dev/sda5)和PV(/dev/sdb1)如下:
root@ubuntudoc:~# pvdisplay
--- Physical volume ---
PV Name /dev/sda5
VG Name ubuntudoc-vg
PV Size 49.76 GiB / not usable 2.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 12738
Free PE 0
Allocated PE 12738
PV UUID ADh3K6-fjVA-5lLY-9vzu-eIxe-utiL-pOYtZa
--- Physical volume ---
PV Name /dev/sdb1
VG Name ubuntudoc-vg
PV Size 16.00 GiB / not usable 3.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 4095
Free PE 0
Allocated PE 4095
PV UUID 2RwFCw-lLul-8CIf-gHvb-0rC1-U0aG-SfHZGd
root@ubuntudoc:~# pvs
PV VG Fmt Attr PSize PFree
/dev/sda5 ubuntudoc-vg lvm2 a-- 49.76g 0
/dev/sdb1 ubuntudoc-vg lvm2 a-- 16.00g 0
logical volume (LV)
LV简单的理解是可以挂载到分区下的磁盘空间了。如下 :根分区/下的空间，代表着root这个lv。
root@ubuntudoc:~# lvs
LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert
root ubuntudoc-vg -wi-ao--- 53.76g
swap_1 ubuntudoc-vg -wi-ao--- 12.00g
2.lvm扩展根目录分区的实战
2.1 设置硬盘/dev/sdb为linux lvm
先决条件:在vmware虚拟化平台下，我先添加了一块/dev/sdb的硬盘，并把硬盘设置为linux lvm,操作如下:
root@ubuntudoc:~# 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 0x502d7728.
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)
Command (m for help): p
Disk /dev/sdb: 17.2 GB, 17179869184 bytes
255 heads, 63 sectors/track, 2088 cylinders, total 33554432 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x502d7728
Device Boot Start End Blocks Id System
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1):
Using default value 1
First sector (2048-33554431, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-33554431, default 33554431):
Using default value 33554431
Command (m for help): p
Disk /dev/sdb: 17.2 GB, 17179869184 bytes
255 heads, 63 sectors/track, 2088 cylinders, total 33554432 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x502d7728
Device Boot Start End Blocks Id System
/dev/sdb1 2048 33554431 16776192 83 Linux
Command (m for help): t
Selected partition 1
Hex code (type L to list codes): L
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 27 Hidden NTFS Win 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 39 Plan 9 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 3c PartitionMagic 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 <32M 40 Venix 80286 85 Linux extended c7 Syrinx
5 Extended 41 PPC PReP Boot 86 NTFS volume set da Non-FS data
6 FAT16 42 SFS 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS/exFAT 4d QNX4.x 88 Linux plaintext de Dell Utility
8 AIX 4e QNX4.x 2nd part 8e Linux LVM df BootIt
9 AIX bootable 4f QNX4.x 3rd part 93 Amoeba e1 DOS access
a OS/2 Boot Manag 50 OnTrack DM 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 51 OnTrack DM6 Aux 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 52 CP/M a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 53 OnTrack DM6 Aux a5 FreeBSD ee GPT
f W95 Ext'd (LBA) 54 OnTrackDM6 a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 55 EZ-Drive a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 56 Golden Bow a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 5c Priam Edisk a9 NetBSD f4 SpeedStor
14 Hidden FAT16 <3 61 SpeedStor ab Darwin boot f2 DOS secondary
16 Hidden FAT16 63 GNU HURD or Sys af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 64 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 65 Novell Netware b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 70 DiskSecure Mult bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 75 PC/IX be Solaris boot ff BBT
1e Hidden W95 FAT1 80 Old Minix
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)
Command (m for help): p
Disk /dev/sdb: 17.2 GB, 17179869184 bytes
255 heads, 63 sectors/track, 2088 cylinders, total 33554432 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x502d7728
Device Boot Start End Blocks Id System
/dev/sdb1 2048 33554431 16776192 8e Linux LVM
Command (m for help): wq
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
2.2 把pv(/dev/sb1)添加至vg中。
命令如下:
root@ubuntudoc:~# vgs
VG #PV #LV #SN Attr VSize VFree
ubuntudoc-vg 1 2 0 wz--n- 49.76g 32.00m
root@ubuntudoc:~# vgextend ubuntudoc-vg /dev/sdb1
No physical volume label read from /dev/sdb1
Physical volume "/dev/sdb1" successfully created
Volume group "ubuntudoc-vg" successfully extended
root@ubuntudoc:~# vgs
VG #PV #LV #SN Attr VSize VFree
ubuntudoc-vg 2 2 0 wz--n- 65.75g 16.03g
上述结果，可以看出ubuntudoc-vg添加至65GB了。
2.3 vg中空闲的空间加入lv中
命令如下:
root@ubuntudoc:~# lvs
LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert
root ubuntudoc-vg -wi-ao--- 37.73g
swap_1 ubuntudoc-vg -wi-ao--- 12.00g
root@ubuntudoc:~# lvextend --help
lvextend: Add space to a logical volume
lvextend
[-A|--autobackup y|n]
[--alloc AllocationPolicy]
[-d|--debug]
[-f|--force]
[-h|--help]
[-i|--stripes Stripes [-I|--stripesize StripeSize]]
{-l|--extents [+]LogicalExtentsNumber[%{VG|LV|PVS|FREE|ORIGIN}] |
-L|--size [+]LogicalVolumeSize[bBsSkKmMgGtTpPeE]}
[-m|--mirrors Mirrors]
[--nosync]
[--use-policies]
[-n|--nofsck]
[--noudevsync]
[-r|--resizefs]
[-t|--test]
[--type VolumeType]
[-v|--verbose]
[--version]
LogicalVolume[Path] [ PhysicalVolumePath... ]
root@ubuntudoc:~# lvextend -l +100%free /dev/ubuntudoc-vg/root （100%剩余的空闲空间全部给与root的lv）
Extending logical volume root to 53.76 GiB
Logical volume root successfully resized
root@ubuntudoc:~# lvs
LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert
root ubuntudoc-vg -wi-ao--- 53.76g
swap_1 ubuntudoc-vg -wi-ao--- 12.00g
2.4 根分区识别空闲的磁盘空间
操作如下:
root@ubuntudoc:~# df -h
Filesystem Size Used Avail Use% Mounted on
udev 989M 4.0K 989M 1% /dev
tmpfs 200M 712K 200M 1% /run
/dev/dm-0 38G 2.6G 33G 8% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup
none 5.0M 0 5.0M 0% /run/lock
none 1000M 0 1000M 0% /run/shm
none 100M 0 100M 0% /run/user
/dev/sda1 236M 40M 184M 18% /boot
root@ubuntudoc:~# resize2fs /dev/ubuntudoc-vg/root
resize2fs 1.42.9 (4-Feb-2014)
Filesystem at /dev/ubuntudoc-vg/root is mounted on /; on-line resizing required
old_desc_blocks = 3, new_desc_blocks = 4
The filesystem on /dev/ubuntudoc-vg/root is now 14092288 blocks long.
root@ubuntudoc:~# df -h
Filesystem Size Used Avail Use% Mounted on
udev 989M 4.0K 989M 1% /dev
tmpfs 200M 712K 200M 1% /run
/dev/dm-0 53G 2.6G 48G 6% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup
none 5.0M 0 5.0M 0% /run/lock
none 1000M 0 1000M 0% /run/shm
none 100M 0 100M 0% /run/user
/dev/sda1 236M 40M 184M 18% /boot
root@ubuntudoc:~#
至此，/分区扩展至53G。