ZFS snapdir readability (Crosspost)

Peter Eriksson pen at lysator.liu.se
Thu Nov 7 22:06:31 UTC 2019

The “easy” solution is to give each user (or group / project) their own ZFS filesystem. Then the “.zfs” directory would be inside the users own $HOME and you can set $HOME to 0700….

That is what we are doing. Granted it generates a “few” filesystems (like some 20000 per server (we have around 120k users), and then add hourly snapshots to each as “icing” on the cake). Mounting all those takes a bit of time - but luckily with the latest FreeBSD release things are much faster these days :-)

There are some other issues with that - like 100% full filesystems causing severe system slowdown during writes… So you really wanna have some monitoring system that warns for that.

- Peter

> I recently noticed that all ZFS filesystems in FreeBSD allow access to
> the .zfs directory (snapdir) for all users of the system. It is
> possible to hide that directory using the snapdir option:

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