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Stefano Marinelli

One of the most fundamental yet little-known features of FreeBSD is its ability to be used in read-only mode very easily. By installing the system on a UFS file system, you just need to modify the fstab file, change "rw" to "ro," and reboot. On the next boot, the system will automatically create mount points in RAM for the main directories (/tmp, log, etc.), and it will run perfectly.

This was the main reason why, many years ago, I chose FreeBSD for almost all my embedded systems. Even today, on my Raspberry Pies, I keep the SD cards in read-only mode and use external storage in read-write mode. This ensures that, in case of an unexpected poweroff, the system will come back up, and there will be no wear on the memory card.

#FreeBSD #EmbeddedSystems #RaspberryPi #ReadOnly #SysAdmin #Tech #OpenSource

5 comments
Graham Perrin

@stefano wow, where did you learn this? Documentation, or discussion?

Stefano Marinelli

@grahamperrin I can't remember as I've been using this for more than 12 years now. I think it comes from NanoBSD. Maybe I should write a blog post about it.

Stewart Russell

@stefano Raspberry Pi OS does this too: select 'Overlay Filesystem' in raspi-config, and you're read-only from next boot.

It's handy

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