Did anyone had the courage to use btrfs in production? Any stories to share?
"Btrfs has played a role in increasing efficiency and resource utilization in Facebook’s data centers in a number of different applications. Recently, Btrfs helped eliminate priority inversions caused by the journaling behavior of the previous filesystem, when used for I/O control with cgroup2 (described below). Btrfs is the only filesystem implementation that currently works with resource isolation, and it’s now deployed on millions of servers, driving significant efficiency gains."
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.
My rough understanding is synology did some pretty heavy modifications to btrfs in their implementation though... (a quick google finds me nothing to back this up, but i remember reading about it somewhere...)
I'd like to see them move to full disk encryption rather then their current approach.
For RAID5, they are using it on top of LVM, but with some modification - the synology implementation hooks LVM and btrfs together, so it gets ZFS-like properties.
There's a guy on the internet, who was playing around with it: https://daltondur.st/syno_btrfs_1/
When I was doing whole rebuilds of Debian, using e.g. 8 parallel builds of >18000 packages, it was creating and destroying a snapshot once every few seconds to minutes, at most 8 snapshots in existence at once. It got unbalanced and went write only every 36 hours. A clean brand new filesystem which never had more than 10% space utilisation and was typically around 1%.
At work: I was told our OpenSUSEs had some failures/data-loss, so we're not using the default btrfs on these. Though I don't know with what version that was (we migrated to OpenSUSE about 3 years ago).