FreeBSD Diskless on Raspberry Pi (8GB) — Troubleshooting Guide

Overview

This post documents a working diskless FreeBSD setup on a Raspberry Pi (8GB) using a UniFi NAS (Debian-based) as the NFS server.
It also highlights common pitfalls, UniFi NAS limitations, and required workarounds.

If you’re trying to boot FreeBSD with:

• / mounted read-only over NFS
• /var mounted read-write over NFS

this guide should save you several hours of troubleshooting.

---

References

Before starting, review the official documentation:

• 📘 FreeBSD Handbook – Diskless Operation
  https://docs.freebsd.org/en/books/handbook/advanced-networking/#network-diskless

---

NFS Server Configuration (UniFi NAS)

Design

Mount Point	NFS Path	Mode
/	fbsdbase/fb143	Read-only
/var	rwvar/rpi8gig	Read-write

⚠️ Note
UniFi NAS does not expose no_root_squash in the UI.
You must edit the exports file manually.

---

/etc/exports.d Configuration

root@UNAS-2:/etc/exports.d# cat shared-*.exports
/var/nfs/shared/server/fbsdbase/fb143 192.168.1.0/24(rw,sync,no_subtree_check,no_root_squash)
/var/nfs/shared/server/rwvar/rpi8gig 192.168.1.0/24(rw,sync,no_subtree_check,no_root_squash)
root@UNAS-2:/etc/exports.d# exportfs -ra

---

Diskless Client Configuration

Editing fstab

1. Mount the diskless root filesystem on another machine
2. chroot into it
3. Edit /etc/fstab

sudo chroot /mnt/server

# NFS root (read-only)
192.168.1.60:/var/nfs/shared/server/fbsdbase/fb143  /     nfs  ro  0  0

# NFS /var (read-write)
192.168.1.60:/var/nfs/shared/server/rwvar/rpi8gig  /var  nfs  rw  0  0

Memory Disk Size

cat /conf/base/etc/md_size
32768

➡️ This allocates a 32 MB memory disk for early boot operations.

---

/var Remount Configuration

cat conf/base/var/diskless_remount
192.168.1.60:/var/nfs/shared/server/rwvar/rpi8gig

---

System Configuration (rc.conf)

hostname="diskless"

ifconfig_DEFAULT="DHCP inet6 accept_rtadv"

sshd_enable="YES"

# Disable Sendmail
sendmail_enable="NONE"
sendmail_submit_enable="NO"
sendmail_outbound_enable="NO"
sendmail_msp_queue_enable="NO"

growfs_enable="YES"
powerd_enable="YES"

# Time sync
ntpdate_enable="YES"
ntpd_enable="YES"
ntpd_sync_on_start="YES"

# NFS / RPC
rpc_statd_enable="YES"
rpc_lockd_enable="YES"

---

syslogd Dependency Fix

Edit /etc/rc.d/syslogd and ensure netif is included:

- REQUIRE: mountcritremote FILESYSTEMS newsyslog
+ REQUIRE: mountcritremote FILESYSTEMS newsyslog netif

This prevents syslog startup failures during diskless boot.

---

Rebuilding /etc Image

Whenever anything under /etc changes, rebuild the archive:

tar -c -v -f conf/base/etc.cpio.gz --format cpio --gzip etc

---

DHCP, TFTP & NetBoot

Ensure your router is configured with:

• DHCP
• TFTP
• Next-server / bootfile options

Example (UniFi UI):

---

TFTP in UNAS

apt update
apt install -y inetutils-inetd tftpd-hpa
chmod -R 755 /var/nfs/shared/server/tftpboot/
chown -R tftp:tftp /var/nfs/shared/server/tftpboot/
#copy required boot files
scp -r freebsd@192.168.1.249:/b/tftpboot/FreeBSD/arm64/* /var/nfs/shared/server/tftpboot/
#restart server
sudo systemctl enable tftpd-hpa
sudo systemctl restart tftpd-hpa

---

Final Notes

✅ Root filesystem over NFS (RO)
✅ /var over NFS (RW)
✅ Stable reboots
✅ Works reliably on Raspberry Pi 8GB

---

Happy hacking & diskless booting! 🚀