[ak217]

At a previous job, I deployed btrfs to production in a system that continuously spins up and shuts down thousands of VMs. A key feature that I was able to leverage to make this easy is seed devices. This btrfs feature works similarly to overlay filesystems.

If I were doing that today, I would do a bake-off of OverlayFS vs. btrfs for this feature. Btrfs has many other compelling features that may make it worth using, although it's always been slower than ext4/xfs so I'd also need to check how it does with modern ultra high performance NVMe drives.

Btrfs never lost our data, although there was a kernel panic in the journal writing code in the Linux 3.2/Ubuntu 12.04 timeframe. The panic would not cause data loss but it did wedge VMs. Since that was fixed, it's had a 100% reliable run in that system, to my knowledge.

[mekster]

I heard people get stable btrfs when certain features are turned off, so it may be helpful to say what you have turned on or off with its features when saying how it has been stable or not.