问题描述 #

我在VPS上尝试安装NFS服务器，但启动失败，提示依赖缺失。执行相关命令后得到以下输出：

查看NFS服务状态 #

root@server:/# sudo systemctl status nfs-server

○ nfs-server.service - NFS server and services
Loaded: loaded (/lib/systemd/system/nfs-server.service; enabled; vendor preset: enabled)
Active: inactive (dead)

Feb 16 19:36:39 server systemd[1]: Dependency failed for NFS server and services.
Feb 16 19:36:39 server systemd[1]: nfs-server.service: Job nfs-server.service/start failed with result 'dependency'.
Feb 16 19:36:39 server systemd[1]: Dependency failed for NFS server and services.
Feb 16 19:36:39 server systemd[1]: nfs-server.service: Job nfs-server.service/start failed with result 'dependency'.
Feb 16 19:42:12 server systemd[1]: Dependency failed for NFS server and services.
Feb 16 19:42:12 server systemd[1]: nfs-server.service: Job nfs-server.service/start failed with result 'dependency'.
Feb 19 12:30:54 server systemd[1]: Dependency failed for NFS server and services.
Feb 19 12:30:54 server systemd[1]: nfs-server.service: Job nfs-server.service/start failed with result 'dependency'.
Feb 19 12:30:55 server systemd[1]: Dependency failed for NFS server and services.
Feb 19 12:30:55 server systemd[1]: nfs-server.service: Job nfs-server.service/start failed with result 'dependency'.

查看NFS内核服务依赖 #

root@server:/# systemctl list-dependencies nfs-kernel-server

nfs-kernel-server.service
○ ├─auth-rpcgss-module.service
○ ├─nfs-idmapd.service
○ ├─nfs-mountd.service
○ ├─nfsdcld.service
× ├─proc-fs-nfsd.mount
● ├─rpc-statd-notify.service
● ├─rpc-statd.service
○ ├─rpc-svcgssd.service
● ├─rpcbind.socket
● ├─system.slice
● ├─network-online.target
● │ ├─ifupdown-wait-online.service
● │ ├─networking.service
× │ └─systemd-networkd-wait-online.service
● └─network.target

可以看到proc-fs-nfsd.mount和systemd-networkd-wait-online.service状态异常（标记为×）。

查看proc-fs-nfsd.mount状态 #

root@server:/# sudo systemctl status proc-fs-nfsd.mount

× proc-fs-nfsd.mount - NFSD configuration filesystem
Loaded: loaded (/lib/systemd/system/proc-fs-nfsd.mount; static)
Active: failed (Result: exit-code) since Mon 2024-02-19 12:30:55 UTC; 1h 28min ago
Where: /proc/fs/nfsd
What: nfsd

Feb 19 12:30:55 server systemd[1]: Mounting NFSD configuration filesystem...
Feb 19 12:30:55 server mount[1997336]: mount: /proc/fs/nfsd: unknown filesystem type 'nfsd'.
Feb 19 12:30:55 server systemd[1]: proc-fs-nfsd.mount: Mount process exited, code=exited, status=32/n/a
Feb 19 12:30:55 server systemd[1]: proc-fs-nfsd.mount: Failed with result 'exit-code'.
Feb 19 12:30:55 server systemd[1]: Failed to mount NFSD configuration filesystem.

查看systemd-networkd-wait-online.service状态 #

root@server:/# sudo systemctl status systemd-networkd-wait-online.service

× systemd-networkd-wait-online.service - Wait for Network to be Configured
Loaded: loaded (/etc/systemd/system/systemd-networkd-wait-online.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Mon 2024-02-19 12:26:07 UTC; 1h 30min ago
Docs: man:systemd-networkd-wait-online.service(8)
Main PID: 1996517 (code=exited, status=1/FAILURE)

Feb 19 12:24:07 server systemd[1]: Starting Wait for Network to be Configured...
Feb 19 12:26:07 server systemd[1]: systemd-networkd-wait-online.service: Main process exited, code=exited, status=1/FAILURE
Feb 19 12:26:07 server systemd[1]: systemd-networkd-wait-online.service: Failed with result 'exit-code'.
Feb 19 12:26:07 server systemd[1]: Failed to start Wait for Network to be Configured.

查看journalctl关键日志 #

NFS服务日志

root@server:/# journalctl -xeu nfs-server

Feb 19 12:30:54 server systemd[1]: Dependency failed for NFS server and services.
Subject: A start job for unit nfs-server.service has failed
Defined-By: systemd
Support: http://www.ubuntu.com/support
A start job for unit nfs-server.service has finished with a failure.
The job identifier is 33900 and the job result is dependency.
Feb 19 12:30:54 server systemd[1]: nfs-server.service: Job nfs-server.service/start failed with result 'dependency'.
Feb 19 12:30:55 server systemd[1]: Dependency failed for NFS server and services.
Subject: A start job for unit nfs-server.service has failed
Defined-By: systemd
Support: http://www.ubuntu.com/support
A start job for unit nfs-server.service has finished with a failure.
The job identifier is 33930 and the job result is dependency.
Feb 19 12:30:55 server systemd[1]: nfs-server.service: Job nfs-server.service/start failed with result 'dependency'.

proc-fs-nfsd.mount日志

root@server:/# journalctl -xeu proc-fs-nfsd.mount

Feb 19 12:30:55 server systemd[1]: Mounting NFSD configuration filesystem...
Subject: A start job for unit proc-fs-nfsd.mount has begun execution
Defined-By: systemd
Support: http://www.ubuntu.com/support
A start job for unit proc-fs-nfsd.mount has begun execution.
The job identifier is 33931.
Feb 19 12:30:55 server mount[1997336]: mount: /proc/fs/nfsd:             unknown filesystem type 'nfsd'.
Feb 19 12:30:55 server systemd[1]: proc-fs-nfsd.mount: Mount     process exited, code=exited, status=32/n/a
Subject: Unit process exited
Defined-By: systemd
Support: http://www.ubuntu.com/support
An n/a= process belonging to unit proc-fs-nfsd.mount has exited.
The process' exit code is 'exited' and its exit status is 32.
Feb 19 12:30:55 server systemd[1]: proc-fs-nfsd.mount: Failed with result 'exit-code'.
Subject: Unit failed
Defined-By: systemd
Support: http://www.ubuntu.com/support
The unit proc-fs-nfsd.mount has entered the 'failed' state with result 'exit-code'.
Feb 19 12:30:55 server systemd[1]: Failed to mount NFSD configuration filesystem.
Subject: A start job for unit proc-fs-nfsd.mount has failed
Defined-By: systemd
Support: http://www.ubuntu.com/support
A start job for unit proc-fs-nfsd.mount has finished with a failure.
The job identifier is 33931 and the job result is failed.

我查了资料，有些VPS镜像可能缺失这些依赖，有人说只能重装系统，但我想知道有没有不用格式化系统就能修复的方法？

解决方法 #

不用重装系统，我们可以分步骤修复这两个依赖问题：

1. 修复proc-fs-nfsd.mount失败问题 #

提示未知文件系统类型'nfsd'，大概率是NFS内核模块没加载，我们手动加载并设置开机自动加载：

• 手动加载nfsd模块：

sudo modprobe nfsd

• 验证模块是否加载成功：

lsmod | grep nfsd

如果输出中有nfsd的条目，说明加载成功。

• 设置开机自动加载该模块：

echo "nfsd" | sudo tee /etc/modules-load.d/nfsd.conf

• 重新挂载proc-fs-nfsd.mount：

sudo systemctl start proc-fs-nfsd.mount

再检查状态：

sudo systemctl status proc-fs-nfsd.mount

如果显示active（mounted）就没问题了。

2. 修复systemd-networkd-wait-online.service失败问题 #

这个服务失败通常是因为它在等待所有网络接口上线，但VPS可能有些接口不需要或者配置有问题，推荐两种解决方式：

方法一：修改服务配置，只等待活跃接口

• 编辑服务配置文件：

sudo systemctl edit systemd-networkd-wait-online.service

• 在打开的编辑器中添加以下内容：

[Service]
ExecStart=
ExecStart=/lib/systemd/systemd-networkd-wait-online --any --quiet

保存退出后，重新加载配置并启动服务：

sudo systemctl daemon-reload
sudo systemctl start systemd-networkd-wait-online.service

检查状态是否正常：

sudo systemctl status systemd-networkd-wait-online.service

方法二：直接禁用不必要的服务

如果你的NFS服务不需要严格等待网络完全在线，也可以直接禁用这个服务：

sudo systemctl disable --now systemd-networkd-wait-online.service

同时，我们可以修改nfs-server.service的依赖，移除对network-online.target的强依赖（可选）：

sudo systemctl edit nfs-server.service

添加以下内容：

[Unit]
After=network.target
Wants=network.target

保存退出后重新加载配置。

3. 重新启动NFS服务 #

修复完两个依赖后，重新启动NFS相关服务：

sudo systemctl restart nfs-kernel-server nfs-server

然后检查NFS服务状态：

sudo systemctl status nfs-server

如果显示active（running），说明成功启动了。

4. 验证NFS服务可用性 #

可以尝试导出一个测试目录，然后在客户端挂载测试，确保服务正常工作。

备注：内容来源于stack exchange，提问作者user1768691