今天突然发现CentOS系统没有nbd模块，只能重新装下，下面记录下整个编译过程：
系统：CentOS6.5
内核：2.6.32-431.el6.x86_64
[root@localhost ~]# yum install -y kernel-headers kernel-devel
[root@localhost ~]# wget ftp://ftp.redhat.com/pub/redhat/linux/enterprise/6ComputeNode/en/os/SRPMS/kernel-2.6.32-431.el6.src.rpm
[root@localhost ~]# rpm -ivh kernel-2.6.32-431.el6.src.rpm
[root@localhost ~]# cd ~/rpmbuild/SOURCES/
[root@localhost SOURCES]# tar jxf linux-2.6.32-431.el6.tar.bz2 -C /usr/src/kernels/
[root@localhost SOURCES]# cd /usr/src/kernels/
[root@localhost kernels]# mv $(uname -r) $(uname -r)-old
[root@localhost kernels]# mv linux-2.6.32-431.el6 $(uname -r)
[root@localhost kernels]# cd $(uname -r)
[root@localhost 2.6.32-431.el6.x86_64]# make mrproper
[root@localhost 2.6.32-431.el6.x86_64]# cp ../$(uname -r)-old/Module.symvers .
[root@localhost 2.6.32-431.el6.x86_64]# cp /boot/config-$(uname -r) ./.config
[root@localhost 2.6.32-431.el6.x86_64]# make oldconfig
[root@localhost 2.6.32-431.el6.x86_64]# make prepare
[root@localhost 2.6.32-431.el6.x86_64]# make scripts
[root@localhost 2.6.32-431.el6.x86_64]# make CONFIG_BLK_DEV_NBD=m M=drivers/block
[root@localhost 2.6.32-431.el6.x86_64]# cp drivers/block/nbd.ko /lib/modules/$(uname -r)/kernel/drivers/block/
[root@localhost 2.6.32-431.el6.x86_64]# depmod -a
至此，nbd模块已经成功编译。
下面加载nbd模块并查看成功装载后的情况：
[root@localhost image]# modprobe nbd max_part=8
[root@localhost image]# ll /dev/nbd*
brw-rw---- 1 root disk 43, 0 Nov 20 21:24 /dev/nbd0
brw-rw---- 1 root disk 43, 16 Nov 20 21:24 /dev/nbd1
brw-rw---- 1 root disk 43, 160 Nov 20 21:24 /dev/nbd10
brw-rw---- 1 root disk 43, 176 Nov 20 21:24 /dev/nbd11
brw-rw---- 1 root disk 43, 192 Nov 20 21:24 /dev/nbd12
brw-rw---- 1 root disk 43, 208 Nov 20 21:24 /dev/nbd13
brw-rw---- 1 root disk 43, 224 Nov 20 21:24 /dev/nbd14
brw-rw---- 1 root disk 43, 240 Nov 20 21:24 /dev/nbd15
brw-rw---- 1 root disk 43, 32 Nov 20 21:24 /dev/nbd2
brw-rw---- 1 root disk 43, 48 Nov 20 21:24 /dev/nbd3
brw-rw---- 1 root disk 43, 64 Nov 20 21:24 /dev/nbd4
brw-rw---- 1 root disk 43, 80 Nov 20 21:24 /dev/nbd5
brw-rw---- 1 root disk 43, 96 Nov 20 21:24 /dev/nbd6
brw-rw---- 1 root disk 43, 112 Nov 20 21:24 /dev/nbd7
brw-rw---- 1 root disk 43, 128 Nov 20 21:24 /dev/nbd8
brw-rw---- 1 root disk 43, 144 Nov 20 21:24 /dev/nbd9
[root@localhost image]#