Are you using a UPS on the desktop? A recent HN thread highlighted BTRFS issues, especially with regards to dataloss on power loss. Also, there's a "write hole issue" on some RAID configurations, RAID 4 or 6 I think.
That said, I'm thinking about leaving a BTRFS partition unmounted and mounting it only to perform backups, taking advantage of the snapshotting features.
This would seem to suggest that ANY raid configuration is unacceptable.
Device replace
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>Device replace and device delete insist on being able to read or reconstruct all data. If any read fails due to an IO error, the delete/replace operation is aborted and the administrator must remove or replace the damaged data before trying again.
Device replace isn't something where "mostly ok" is a good enough status.
I interpreted "being able to read or reconstruct all data" as meaning that there must exist a good valid copy of each chunk of data somewhere in the array, but not necessarily on the device that you're trying to remove or replace. That interpretation matches my experience, which is that btrfs can correctly handle replacing a drive that is dead or dying. You should certainly expect errors if eg. both copies of a chunk in a RAID1 are lost/corrupted.
That said, I'm thinking about leaving a BTRFS partition unmounted and mounting it only to perform backups, taking advantage of the snapshotting features.