使用qemu-nbd挂载qcow2镜像文件

1. 加载 nbd 驱动

某些版本的 linux 不加 max_part 参数会导致没有没有设备节点 /dev/nbd0p{1,2,3,4…} 等. 用 kpartx 也不行.

$ sudo modprobe nbd max_part=8

备注信息：查看Linux 模块信息（modinfo），例如查看nbd模块的参数

$ modinfo nbd
filename:       /lib/modules/3.14.12/kernel/drivers/block/nbd.ko
license:        GPL
description:    Network Block Device
srcversion:     910DE7DFCE8A0AE76D3D428
depends:        
intree:         Y
vermagic:       3.14.12 SMP mod_unload modversions 
parm:           nbds_max:number of network block devices to initialize (default: 16) (int)
parm:           max_part:number of partitions per device (default: 0) (int)
parm:           debugflags:flags for controlling debug output (int)

2.连接 qemu-nbd

$ sudo qemu-nbd -c /dev/nbd0 centos.qcow2

查看分区:

$ sudo fdisk -l /dev/nbd0

Disk /dev/nbd0: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders, total 20971520 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: 0x0005d1fd

     Device Boot      Start         End      Blocks   Id  System
/dev/nbd0p1   *        2048     1026047      512000   83  Linux
/dev/nbd0p2         1026048    20971519     9972736   8e  Linux LVM

vgdisplay

$ sudo lvdisplay

  --- Logical volume ---
  LV Name                /dev/VolGroup/lv_root
  VG Name                VolGroup
  LV UUID                v60jyE-1lDm-7dMW-hkVf-YWBH-OKXI-ySHDkb
  LV Write Access        read/write
  LV Status              NOT available
  LV Size                8.51 GiB
  Current LE             2178
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
   
  --- Logical volume ---
  LV Name                /dev/VolGroup/lv_swap
  VG Name                VolGroup
  LV UUID                b1BctN-vPtc-8n6F-tokb-75pN-w34N-HXG1cB
  LV Write Access        read/write
  LV Status              NOT available
  LV Size                1.00 GiB
  Current LE             256
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto

Active VolGroup

$ sudo vgchange -a y VolGroup

mount vg

$ sudo mount /dev/VolGroup/lv_root /mnt/test2

3.挂载

$ sudo mount /dev/nbd0p1 /mnt/test1

4.umount disconnect

$ sudo mount /dev/nbd0p1 /mnt/test1
$ sudo qemu-nbd -d /dev/nbd0p1