Purpose

I have a macmini only have 256G SSD and meanwhile have a NAS with 30T, Find some way to automount NAS NFS to macmini for extend HDD size

Research

As we know macos is from Unix, Unix system basically all support NFS, after research find that macos support automount, master file location is /etc/auto_master

Considering the network latency and bandwidth, I will not put any small files into automount folder

Here is my plan

1. Create NFS share on NAS
2. Create a mount point on macos
3. Add nfs auto mount define file on macos
4. Add nfs auto mount define file to auto_master

Implement

Skip NFS create step

Create a mount point for NFS on macos

mkdir -p /System/Volumes/Data/nfs

For now I have these NFS mount point on my NAS

% showmount -d 192.168.3.240
Directories on 192.168.3.240:
/volume1/BaiduPan
/volume1/MacMiniData
/volume1/Movies
/volume1/Music
/volume1/Shares
/volume1/roms

create /etc/auto_nfs

data -fstype=nfs,soft,resvport,rw,noowners 192.168.3.240:/volume1/MacMiniData
movies -fstype=nfs,soft,resvport,noowners 192.168.3.240:/volume1/Movies
music -fstype=nfs,soft,resvport,noowners 192.168.3.240:/volume1/Music

add /etc/auto_nfs to auto_master

...
/System/Volumes/Data/nfs auto_nfs

last active automount

automount -vc

Issues

Sometime(Maybe system update) auto_master will lost auto_nfs define, please add back manually

or use this script to check regularly

#!/bin/sh

[ $UID -ne 0 ] && echo "require root permission" && exit 1

if [ $(grep '^/System/Volumes/Data/nfs auto_nfs' -c /etc/auto_master) -eq 0 ];then
    echo '/System/Volumes/Data/nfs auto_nfs' >> /etc/auto_master && automount -vc
fi