我遵循了这里概述的步骤：https://www.howtoforge.com/how-to-install-nfs-server-and-client-on-ubuntu-22-04/：
在一台 Ubuntu 22.04 VPS (NFS 服务器)中：
已安装 nfs-kernel-server
root@k8s-eu-1-worker-1:~# sudo apt install nfs-kernel-server
并启用它
root@k8s-eu-1-worker-1:~# sudo systemctl is-enabled nfs-server
enabled
root@k8s-eu-1-worker-1:~# 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: active (exited) since Wed 2023-11-01 20:56:05 CET; 34s ago
Main PID: 2098 (code=exited, status=0/SUCCESS)
CPU: 13ms
Nov 01 20:56:05 k8s-eu-1-worker-1 systemd[1]: Starting NFS server and services...
Nov 01 20:56:05 k8s-eu-1-worker-1 exportfs[2097]: exportfs: can't open /etc/exports for reading
Nov 01 20:56:05 k8s-eu-1-worker-1 systemd[1]: Finished NFS server and services.
root@k8s-eu-1-worker-1:~# cat /proc/fs/nfsd/versions
-2 +3 +4 +4.1 +4.2
我已经设置了共享目录：
root@k8s-eu-1-worker-1:~# sudo mkdir -p /srv/backups /mnt/shared
root@k8s-eu-1-worker-1:~# sudo chown -R nobody:nogroup /srv/backups /mnt/shared
root@k8s-eu-1-worker-1:~# sudo chmod 777 /srv/backups /mnt/shared
root@k8s-eu-1-worker-1:~# cat /etc/exports
# /etc/exports: the access control list for filesystems which may be exported
# to NFS clients. See exports(5).
#
# Example for NFSv2 and NFSv3:
# /srv/homes hostname1(rw,sync,no_subtree_check) hostname2(ro,sync,no_subtree_check)
#
# Example for NFSv4:
# /srv/nfs4 gss/krb5i(rw,sync,fsid=0,crossmnt,no_subtree_check)
# /srv/nfs4/homes gss/krb5i(rw,sync,no_subtree_check)
#
/srv/backups 192.168.5.100(rw,sync,no_subtree_check)
/mnt/shared 192.168.10.0/24(rw,sync,no_subtree_check)
重新启动 NFS 服务器
root@k8s-eu-1-worker-1:~# sudo systemctl restart nfs-server
root@k8s-eu-1-worker-1:~# 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: active (exited) since Wed 2023-11-01 21:05:28 CET; 12s ago
Process: 2758 ExecStartPre=/usr/sbin/exportfs -r (code=exited, status=0/SUCCESS)
Process: 2759 ExecStart=/usr/sbin/rpc.nfsd (code=exited, status=0/SUCCESS)
Main PID: 2759 (code=exited, status=0/SUCCESS)
CPU: 16ms
Nov 01 21:05:28 k8s-eu-1-worker-1 systemd[1]: Starting NFS server and services...
Nov 01 21:05:28 k8s-eu-1-worker-1 systemd[1]: Finished NFS server and services.
并检查 NFS 服务器上可用的共享目录：
root@k8s-eu-1-worker-1:~# sudo exportfs -v
/srv/backups 192.168.5.100(sync,wdelay,hide,no_subtree_check,sec=sys,rw,secure,root_squash,no_all_squash)
/mnt/shared 192.168.10.0/24(sync,wdelay,hide,no_subtree_check,sec=sys,rw,secure,root_squash,no_all_squash)
在另一个 Ubuntu 22.04 VPS (NFS 客户端) 中：
我安装了 nfs-common
root@k8s-eu-1-master:~# sudo apt install nfs-common
我已经设置了共享目录
root@k8s-eu-1-master:~# sudo mkdir -p /mnt/data
但是我收到此错误：mount.nfs: Resource temporarily unavailable
当我尝试将共享目录“/srv/backups”挂载到目标目录“/mnt/data”时：
root@k8s-eu-1-master:~# sudo mount nfs_server_ip:/srv/backups /mnt/data
mount.nfs: Resource temporarily unavailable
已完成检查（根据此处的迹象：无法在 Ubuntu 22.04 上挂载 nfs）：
从“服务器” ping“客户端” 和反之亦然
/etc/fstab在CLIENTVPS 中：
root@k8s-eu-1-master:~# cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point> <type> <options> <dump> <pass>
# / was on /dev/sda2 during installation
UUID=4f2f752a-bc7e-405f-8dbd-919cee645fab / ext4 errors=remount-ro 0 0
# /boot was on /dev/sda1 during installation
UUID=6ff53e6c-17f5-48a4-bb01-44851a39fa1e /boot ext4 defaults,noatime 0 0
nfs_server_ip:/srv/backups /mnt/data nfs auto,ext4,nofail,noatime,nolock,intr,tcp,actimeo=1800 0 0
尝试了不同版本的“sudo mount”命令：
root@k8s-eu-1-master:~# sudo mount -t nfs -o mouuntvers=4.0 nfs_server_ip:/srv/backups /mnt/data
mount.nfs: Resource temporarily unavailable
root@k8s-eu-1-master:~# sudo mount -t nfs -o mountvers=3 nfs_server_ip:/srv/backups /mnt/data
mount.nfs: Resource temporarily unavailable
root@k8s-eu-1-master:~# sudo mount -t nfs -o mountvers=4.0 nfs_server_ip:/srv/backups /mnt/data
mount.nfs: Resource temporarily unavailable
ufw 状态：
client:
root@k8s-eu-1-master:~# sudo ufw status
Status: inactive
server:
root@k8s-eu-1-worker-1:~# sudo ufw status
Status: inactive
/etc/fstab改变 ：
#nfs_server_ip:/srv/backups /mnt/data nfs auto,ext4,nofail,noatime,nolock,intr,tcp,actimeo=1800 0 0 mountvers=4.0
192.168.1.10:/srv/backups /mnt/data nfs4 auto,mountvers=4 0 0
root@k8s-eu-1-master:~# sudo mount nfs_server_ip:/srv/backups /mnt/data
mount.nfs: Resource temporarily unavailable
rpcinfo -p一边server：
root@k8s-eu-1-worker-1:~# rpcinfo -p
program vers proto port service
100000 4 tcp 111 portmapper
100000 3 tcp 111 portmapper
100000 2 tcp 111 portmapper
100000 4 udp 111 portmapper
100000 3 udp 111 portmapper
100000 2 udp 111 portmapper
100005 1 udp 43114 mountd
100005 1 tcp 32905 mountd
100005 2 udp 51857 mountd
100005 2 tcp 58259 mountd
100005 3 udp 36062 mountd
100005 3 tcp 41271 mountd
100024 1 udp 60988 status
100024 1 tcp 44101 status
100003 3 tcp 2049 nfs
100003 4 tcp 2049 nfs
100227 3 tcp 2049
100021 1 udp 43294 nlockmgr
100021 3 udp 43294 nlockmgr
100021 4 udp 43294 nlockmgr
100021 1 tcp 44757 nlockmgr
100021 3 tcp 44757 nlockmgr
100021 4 tcp 44757 nlockmgr
如何让它工作？
答案1
感谢此处发现的迹象：https://www.digitalocean.com/community/tutorials/how-to-set-up-an-nfs-mount-on-ubuntu-22-04
我/etc/exports在SERVER机器上修改了：
/srv/backups yy.yyy.yyy.yy(rw,sync,no_subtree_check)
/mnt/shared yy.yyy.yyy.yy/24(rw,sync,no_subtree_check)
其中 yy.yyy.yyy.yy 是实际客户端机器的 IP 地址
问题就解决了