It's orphaned in Debian as well, but I'm not sure what significant advantages it has over btrfs, which is very stable these days.
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Also see https://www.phoronix.com/news/Josef-Bacik-Leaves-Meta
*caveat: I’m using RAID 10, not a parity RAID. It could have problems with parity RAID. So? If you really really want RAID 5, then just use md to make your RAID 5 device and put btrfs on top.