OpenBSD currently defaults its FFS filesystems to version 2 instead of version 1 since OpenBSD 6.7. It will not change the old version of FFS1 to FFS2 during sysupgrade. The only way to get a new version is if you create a new filesystem manually by using newfs(8) command or make a new installation of OpenBSD (6.7 and later).

In OpenBSD 6.7, if you create a new filesystem manually (using newfs), you will still get an FFS1 filesystem unless you force -O2 or if the filesystem is more significant than 1 TB. But for the later version, it already defaults the filesystem to FFS2 when you create using the newfs command.

The benefits and restrictions of FFS2:

  • FFS2 is faster to create (using newfs) and is usually quicker to check (using fsck(8), which is run during boot) when compared to FFS1.
  • FFS2 uses 64-bit timestamps and block numbers. That means it handles dates after 2038 and much larger partitions.
  • Large partitions still require large amounts of memory to check, so create multi-petabyte filesystems at your own peril.
  • No tool will convert from FFS1 to FFS2, and you will have to back up your data and reformat your filesystems.

How to Check For the Version

If you’re in doubt about what FFS your filesystems currently are, you can do this:

# dumpfs /dev/rsdXX | head -1

E.g.:

# dumpfs /dev/rsd1i | head -1
magic	19540119 (FFS2) time	Thu Oct 12 13:23:06 2022

This tells you that your sd1i filesystem is FFS2.

Let’s check for another partition:

# dumpfs /dev/rsd0h | head -1 
magic	11954 (FFS1)  time Thu Oct 12 13:24:13 2022

This one is the old FFS1 and will continuously be the same until you reformat or reinstall the operating system.

Conclusion

If you look at /etc/fstab on a new install, it still says ffs without telling you which one it is. So, the above command should make it more straightforward in case you need to be reminded which of your boxes are FFS1 and which are FFS2 in the future. FFS1 will remain supported, so there is no need to convert FFS1 to FFS2 for the foreseeable future, but you might want to convert if you are interested in the benefits of FFS2.

FFS2 allocates inode pages on demand. That means that initially, much less meta-data needs to be initialized (fast newfs) and that when not many inodes are in use (pretty typical), fewer inodes need to be checked (faster fsck).