lvm 分区扩展

有一个服务器通过 targetcli 分发 lvm 部分，比如块磁盘。在 lvextend 的帮助下扩展，lv_pub 部分从 300 GB 增加到 350 GB。

# pvs
  PV         VG             Fmt  Attr PSize   PFree  
  /dev/md126 centos_tgt4 lvm2 a--  465.13g 160.00m
  /dev/sda1  vg_tgt4     lvm2 a--   16.37t   3.22t

# vgs
  VG             #PV #LV #SN Attr   VSize   VFree  
  centos_tgt4   1   4   0 wz--n- 465.13g 160.00m
  vg_tgt4       1   5   0 wz--n-  16.37t   3.22t

# lvs
  LV             VG             Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  home           centos_tgt4 -wi-ao---- 429.06g                                                    
  root           centos_tgt4 -wi-ao----   9.96g                                                    
  swap           centos_tgt4 -wi-ao----  15.96g                                                    
  var            centos_tgt4 -wi-ao----  10.00g                                                    
  lv_cub         vg_tgt4     -wi-ao----   1.00t                                                    
  lv_group       vg_tgt4     -wi-ao----   4.50t                                                    
  lv_home        vg_tgt4     -wi-ao----   1.50t                                                    
  lv_doc         vg_tgt4     -wi-ao----   5.81t                                                    
  lv_pub         vg_tgt4     -wi-ao---- 350.00g

#targetcli
targetcli shell version 2.1.fb41
Copyright 2011-2013 by Datera, Inc and others.
For help on commands, type 'help'.

/> ls
o- / ......................................................................................................................... [...]
  o- backstores .............................................................................................................. [...]
  | o- block .................................................................................................. [Storage Objects: 5]
  | | o- cub ................................................................... [/dev/vg_tgt4/lv_cub (1.0TiB) write-thru activated]
  | | o- group ........................................................ [/dev/mapper/vg_tgt4-lv_group (4.5TiB) write-thru activated]
  | | o- home .......................................................... [/dev/mapper/vg_tgt4-lv_home (1.5TiB) write-thru activated]
  | | o- doc ............................................................ [/dev/mapper/vg_tgt4-lv_doc (5.8TiB) write-thru activated]
  | | o- pub ................................................................. [/dev/vg_tgt4/lv_pub (350.0GiB) write-thru activated]

在客户端上看不到空间增加了：

# pvs
  PV         VG     Fmt  Attr PSize    PFree 
  /dev/sdc   vg_cub lvm2 a--  1024.00g 24.00g
  /dev/sde   vg_pub lvm2 a--   300.00g 10.00g

fdisk，看到磁盘被放大了，但是没有看到分区：

# fdisk /dev/sde
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xa81facb2.
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)

The device presents a logical sector size that is smaller than
the physical sector size. Aligning to a physical sector (or optimal
I/O) size boundary is recommended, or performance may be impacted.

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/sde: 375.8 GB, 375809638400 bytes
255 heads, 63 sectors/track, 45689 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 262144 bytes
Disk identifier: 0xa81facb2

   Device Boot      Start         End      Blocks   Id  System

Command (m for help): ^C