We have been using ZFS for a couple of years now with ubuntu on 4 machines managing a total of ~160 TB of raw storage and have had 0 problems. We chose it mainly because we wanted something very reliable with checksumming and because we consider it to be much more mature and stable than btrfs.

Prior to that we used proprietary RAID hardware that, while fast, did not have checksumming and was frankly a nightmare to manage.

If I had it to do over, I'd choose ZFS again.

I switched to FreeBSD solely because of ZFS, but if I had to use Linux it would be with ZFS too. It's much older and proven. Everything else seems to not be ready yet while ZFS has been stable for years and it keeps advancing ahead of the competition.

BTRFS can get exceedingly slow if you make lots of snapshots (even if you don't keep very many at a time).

ZFS works well for basic data storage and snapshots, but the deduplication has a ton of overhead and is extremely slow on hard drives. And there is no way to make a plain copy-on-write copy of a file without using the full deduplication mode.

I haven't tried either on windows directly, I've accessed them as a file share via a VM.

From my research:

ZFS is more stable, has the downside of not allowing expansion of volumes, and has the issue of not being upstreamed.

BTRfs has the option to expand volumes, is native to Linux, but has a wiff of unstability. Most notably with the persisting raid 5 write hole.

I haven't found a good choice yet. Though I think I'd go btrfs at the moment.

Zfs does allow pools to be expanded by adding vdevs.

What it doesn’t allow is for raid sets to be expanded by replacing with larger disks one at a time. This can however be done with mirrored sets. Add new larger discs to the mirror set, wait for resilvering, remove older smaller discs, done.

0.8 will also bring the ability to remove vdevs so effectively shrink a pool through a similar (but slightly different) process.

But even though you can add vdevs, it doesn’t rebalance the mirror. This means your entire pool, albeit larger, is still slower.

(Unless this is a change that will be brought about in 0.8, I haven’t followed that closely).

Not quite right - you absolutely can expand raidz vdevs by replacing the disks one at a time. What you can't do is increase the "width" of the raidz, or seamlessly rebalance data between multiple vdevs.

> ZFS is more stable, has the downside of not allowing expansion of volumes

No longer true. I’ve expanded volumes on Ubuntu with ZoL.

I hear btrfs is fine on single drives. ZFS is in general what you want to use if you care about your data, at least in RAID setups.

I imagine either should work fine over SAMBA (if that's what you have in mind for Windows). I know there's some work being done to get ZFS working on Windows, and I don't believe there's anything of the sort for btrfs.