You know, ZFS, ButterFS (btrfs…its actually “better” right?), and I’m sure more.
I think I have ext4 on my home computer I installed ubuntu on 5 years ago. How does the choice of file system play a role? Is that old hat now? Surely something like ext4 has its place.
I see a lot of talk around filesystems but Ive never found a great resource that distiguishes them at a level that assumes I dont know much. Can anyone give some insight on how file systems work and why these new filesystems, that appear to be highlights and selling points in most distros, are better than older ones?
Edit: and since we are talking about filesystems, it might be nice to describe or mention how concepts like RAID or LUKS are related.
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As with every software/product: they have different features.
ZFS is not really hip. It’s pretty old. But also pretty solid. Unfortunately it’s licensed in a way that is maybe incompatible with the GPL, so no one wants to take the risk of trying to get it into Linux. So in the Linux world it is always a third-party-addon. In the BSD or Solaris world though …
btrfs has similar goals as ZFS (more to that soon) but has been developed right inside the kernel all along, so it typically works out of the box. It has a bit of a complicated history with it’s stability/reliability from which it still suffers (the history, not the stability). Many/most people run it with zero problems, some will still cite problems they had in the past, some apparently also still have problems.
bcachefs is also looming around the corner and might tackle problems differently, bringing us all the nice features with less bugs (optimism, yay). But it’s an even younger FS than btrfs, so only time will tell.
ext4 is an iteration on ext3 on ext2. So it’s pretty fucking stable and heavily battle tested.
Now why even care? ZFS, btrfs and bcachefs are filesystems following the COW philisophy (copy on write), meaning you might lose a bit performance but win on reliability. It also allows easily enabling snapshots, which all three bring you out of the box. So you can basically say “mark the current state of the filesystem with tag/label/whatever ‘x’” and every subsequent changes (since they are copies) will not touch the old snapshots, allowing you to easily roll back a whole partition. (Of course that takes up space, but only incrementally.)
They also bring native support for different RAID levels making additional layers like mdadm unnecessary. In case of ZFS and bcachefs, you also have native encryption, making LUKS obsolete.
For typical desktop use: ext4 is totally fine. Snapshots are extremely convenient if something breaks and you can basically revert the changes back in a single command. They don’t replace a backup strategy, so in the end you should have some data security measures in place anyway.
*Edit: forgot a word.
ZFS is a crazy beast that’s best for high end server systems with tiered storage and lots of RAM.
ext4 is really just a basic file system. Its superior to NTFS and fat as it does have extra features to try to prevent corruption but it doesn’t have a large feature set.
Btrfs is kind of the new kid on the block. It has strong protection against corruption and has better real world performance than ext4. It also has more advanced features like sub volumes and snapshots. subvolumes are basically virtual drives.
Another few older options include things like XFS but I won’t go into those.
List of filesystems: https://en.m.wikipedia.org/wiki/Comparison_of_file_systems
I use f2fs on my Raspberry Pis, it’s designed for flash storage and appears to have much better performance than ext4 on the same device. I’m not sure whether it’s suitable for SSDs, or just SD cards and USB (these devices are optimised for FAT and f2fs utilises that optimisation). When I tried to use f2fs on a proper laptop it was too early and the distro didn’t support booting from it. I assume that has changed now.
As for the others, I usually stick with ext4 as I’ve never seen a compelling reason not to.
