搭建NBD Server的过程

服务器192.×.×.84，客户端192.×.×.86

在84机器上

安装nbd-server
sudo apt install nbd-server

创建一个300MB的文件当做块设备
/home/kunlun/rxsunSource/tmp下执行
dd if=/dev/zero of=nbd-disk0 bs=104857600 count=3

启动nbd-server，监听9999端口，挂载刚刚创建的nbd-disk0设备
kunlun@kunlunsec:~/rxsunSource/tmp$ sudo nbd-server 9999 /home/kunlun/rxsunSource/tmp/nbd-disk0

** (process:22663): WARNING **: Specifying an export on the command line no longer uses the oldstyle protocol.

查看nbd端口和进程：
kunlun@kunlunsec:~/rxsunSource/tmp$ sudo netstat -antpl | grep 9999

tcp6       0      0 :::9999                 :::*                    LISTEN      13444/nbd-server

kunlun@kunlunsec:~/rxsunSource/tmp$ ps -ef | grep nbd

nbd      13444 13922  0 15:46 ?        00:00:00 nbd-server 9999 /home/kunlun/rxsunSource/tmp/nbd-disk0
kunlun   13474 32318  0 15:47 pts/25   00:00:00 grep --color=auto nbd

在86机器上

sudo apt install nbd-client
modprobe nbd 载入模块
$ lsmod | grep nbd 查看nbd设备是否建立.

nbd                    20480  0

$ ls /dev/nbd* -hl 查看设备

brw-rw---- 1 root disk 43,   0 8月  28 14:02 /dev/nbd0
.........
brw-rw---- 1 root disk 43, 240 8月  28 14:02 /dev/nbd15
.........
brw-rw---- 1 root disk 43, 144 8月  28 14:02 /dev/nbd9

$ sudo nbd-client 192.168.200.84 9999 /dev/nbd0 将nbd设备关联到nbd服务器端

Warning: the oldstyle protocol is no longer supported.
This method now uses the newstyle protocol with a default export
Negotiation: ..size = 300MB
bs=1024, sz=314572800 bytes

$ ps -ef | grep nbd 查看nbd-client进程.

root      4957     1  0 14:04 ?        00:00:00 nbd-client 192.168.200.84 9999 /dev/nbd0
root      4959     2  0 14:04 ?        00:00:00 [nbd0]

$ mkdir /mnt/nbd0
$ mount /dev/nbd0 /mnt/nbd0 将/dev/nbd0设备挂载到/mnt/nbd0目录下，不理睬提示信息

mount: /dev/nbd0 is write-protected, mounting read-only
mount: wrong fs type, bad option, bad superblock on /dev/nbd0,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail or so.

$ cd /mnt/nbd0/ 进入目录
$ touch a.txt 创建一个文件
$ ll 验证文件创建成功

total 8
drwxr-xr-x 2 root root 4096 8月  28 14:13 ./
drwxr-xr-x 3 root root 4096 8月  28 14:10 ../
-rw-r--r-- 1 root root    0 8月  28 14:13 a.txt

执行以下命令结束nbd设备和连接
$ umount /mnt/nbd0/
$ nbd-client -d /dev/nbd0 用于断开到nbd server的连接

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