■ Premises

As pretty much any other UNIX system, NetBSD provides solid in-kernel NFS support. See nfsssvc(2)

Since I only run Windows occasionally (mainly for MS-Office or MATLAB) and all of my machines either run NetBSD, Slackware or Tribblix, it makes sense for me to opt for NFS as a distributed file system protocol to share files from my server over the local network.

■ Server setup

(Also Refer to 29.1. The Network File System (NFS))

1. Preliminary tasks

First of all, if you run a custom kernel, make sure to have support built-in, by inspecting your config:

$ config -x /netbsd | grep NFS

Which should at least return:

###>	file-system     NFS             # Network File System client
###>	options         NFSSERVER       # Network File System server

In /etc/sysctl.conf, set the number of kernel threads created to serve asynchronous NFS I/O requests:

# Number of kernel threads to use for NFS client
vfs.nfs.iothreads=6

2. Configure a NFS server

I want make the following ZFS datasets available on the local network:

NAME        USED  AVAIL  REFER  MOUNTPOINT
zfs/data   6.96G   493G  6.96G  /zfs/data	# pdfs, misc 
zfs/music  22.9G  77.1G  22.9G  /zfs/music	# music
zfs/p2p     108G  1.61T   108G  /zfs/p2p	# torrent destdir 
zfs/pkg    3.95G  96.0G  3.95G  /zfs/pkg	# binary packages

First, create an /etc/exports file with the following content:

/zfs/data       -alldirs -maproot=vms -network 192.168.1.0 -mask 255.255.255.0
/zfs/music      -alldirs -maproot=vms -network 192.168.1.0 -mask 255.255.255.0
/zfs/p2p        -alldirs -maproot=vms -network 192.168.1.0 -mask 255.255.255.0
/zfs/pkg        -alldirs -maproot=vms -network 192.168.1.0 -mask 255.255.255.0

This tells mountd(8) to serve the datasets (and all subdirectories) for NFS mount requests coming from local client machines. The client's root user shall access the shared directories as if it was user vms on the server. See exports(5).

Now, let's look at relevant rc.d services.
Within /etc/rc.conf:

rpcbind=YES		# required for Sun RPC services like lockd and statd
mountd=YES		# handle file-system mount requests 	
nfs_server=YES		# rcvar for nfsd
nfsd_flags='-n6'	# NFS I/O threads to create
lockd=YES		# handle record-locking operations on NFS file 
statd=YES		# crash and recovery functions for the lock manager

Note: the lockd and statd services are handled by the /etc/rc.d/nfslocking rc script.

Enable the services:

$ for var in rpcbind mountd nfsd nfslocking
    > do service $var start
    > done

3. Firewall settings

We need to tell NPF to allow inbound traffic on NFS/RCP services coming from the local network.
First let's check which ports were assigned to RPC services:

$ rpcinfo -p
                                                                      

   program vers proto   port  service
    100024    1   udp   1014  status
    100024    1   tcp   1017  status
    100021    0   udp   1013  nlockmgr
    100021    1   udp   1013  nlockmgr
    100021    3   udp   1013  nlockmgr
    100021    4   udp   1013  nlockmgr
    100021    0   tcp   1016  nlockmgr
    100021    1   tcp   1016  nlockmgr
    100021    3   tcp   1016  nlockmgr
    100021    4   tcp   1016  nlockmgr
    100005    1   udp   1012  mountd
    100005    3   udp   1012  mountd
    100005    1   tcp   1015  mountd
    100005    3   tcp   1015  mountd
    100003    2   udp   2049  nfs
    100003    3   udp   2049  nfs
    100003    2   tcp   2049  nfs
    100003    3   tcp   2049  nfs

Then, by editing /etc/npf.conf, make sure these ports are opened to local clients:

$LAN = { 192.168.1.0/24 }
$services_nfs = { rpcbind, nfsd, 1012-1017 }
pass stateful in final from $LAN to $int_if port $services_nfs apply "log"

Atomically update the NPF ruleset:

$ npfctl reload

Now if everything went well, you should see the datasets available as NFS shares by running the showmount(8) command from a client machine:

$ showmount -e homelab 
Export list for homelab:
/zfs/data  192.168.1.0
/zfs/music 192.168.1.0
/zfs/p2p   192.168.1.0
/zfs/pkg   192.168.1.0

Note: the server's internal address is assigned the name 'homelab' on the client's /etc/hosts file.

■ Client setup

1. Make sure to have:

rpcbind=yes
nfs_client=yes
lockd=yes
statd=yes

inside /etc/rc.conf.

2. Start the services:

$ service rpcbind start
$ service nfslocking start

■ Automounting NFS shares on NetBSD

A NetBSD NFS client is probably less common than a NFS server.
But what if we run NetBSD on the desktop?
Let's see the available options to automatize mounting NFS shares on NetBSD.

1. fstab

We can use /etc/fstab to define mount points and mount options on the client machine:

homelab:/zfs/data	/net/data	nfs	rw,noauto,intr,timeo=14 0 0
homelab:/zfs/music	/net/music	nfs	rw,noauto,intr,timeo=14 0 0
homelab:/zfs/p2g	/net/p2p	nfs	rw,noauto,intr,timeo=14 0 0
homelab:/zfs/pkg	/net/pkg	nfs	rw,noauto,intr,timeo=14 0 0

Notes:

The intr mount option allows NFS requests to be interrupted if the server goes down or cannot be reached. Will avoid hanging.
timeo=n defines the time (in tenths of a second) the NFS client waits for a response before it retries an NFS request. Default is 30.
It is highly advisable to use noauto in order to avoid boot failures while mounting filesystems if the server is unreacheable (e.g. outside
of the local netwotk)
You may want to also play with rsize=num and wsize=num, which define the maximum number of bytes in each READ/WRITE request that the
NFS client can receive/send when communicating with a NFS server. On NetBSD this is set by default to 32K on amd64 and aarch64, to 8192 on
other platforms.

With such entries on fstab, all that's required to mount any shared dataset is:

$ mount <mountpoint>

For example, to mount homelab:/zfs/music, I'd use:

$ mount /net/music

2. amd(8)

We can use amd(8) on NetBSD to automount NFS shares.
From the man page:

Amd is a daemon that automatically mounts filesystems whenever a file
or directory within that filesystem is accessed. Filesystems are auto-
matically unmounted when they appear to have become quiescent.

First, a map file is needed to tell amd how to resolve the lookup on the target filesystem to mount.

In this case I'll add a second [ /map ] section to my /etc/amd.conf, telling amd to use the mapfile named 'net' to mount the NFS-shared dataset under /net:

[ global ]
karch             = amd64
auto_dir          = /amd
unmount_on_exit   = no
restart_mounts    = yes
browsable_dirs    = yes
print_pid         = no
print_version     = no
dismount_interval = 5
cache_duration    = 5
localhost_address = 127.0.0.1
log_file          = /var/log/amd.log
log_options       = all
search_path       = /etc/amd
map_type          = file
map_options       = cache:=all

[ /media ]
map_name =			media

[ /net ]
map_name =			net

Make sure that the required directories are in place.
amd scans the $search_path for map files, uses $auto_dir to mount filesystems, and the directory specified by the [ /map ] section to make them available as NFS shares.

$ for dir in /amd /etc/amd /net
    > do [ -d "$dir" ] || mkdir $dir
    > done

A sample /etc/amd/net mapfile for NFS shares is provided below:

/defaults	type:=host;rhost:=${key};fs:=${autodir}/${rhost}/root

pub	type:=host;rhost:=homelab;fs:=${autodir}/${rhost}/root

Such map will mount any filesystems shared via NFS by the host homelab inside /amd/homelab/root, whenever a user tries to access /net, and symlink /amd/homelab/root to /net/pub. The shared datasets will be made available inside /net/pub.

Now, let's (re)start amd:

$ service amd restart
Stopping amd.
Starting amd.
Nov  4 16:23:39 beastie amd[14853]/info:  using configuration file /etc/amd.conf
$ amq
/       root    "root"          

/media  toplvl  /etc/amd/media  /media
/net    toplvl  /etc/amd/net    /net

Trying to access /net makes amd mount the shared filesystems:

$ file /net/pub
pub: symbolic link to /amd/homelab/root
$ cd /net/pub/zfs && ls
data/  music/ p2p/   pkg/
$ amq -m | grep homelab
homelab:/net/pub  /amd/homelab/root  host  0  	homelab.retrobsd.ddns.net is up

3. autofs

TODO
Likely covered in a separated post about autofs/automountd.

Also available on my blog at: https://retrobsd.ddns.net/n0bqc3.htm