[justsomehnguy]

> It's reasonable to want to preserve all the data you currently have—some of which probably hasn't been backed up yet—and not accept new data to be written with the durability guarantees the array was originally configured for silently violated.

IE (by your logic) the system should stop the writes as soon as the array became degraded.

But this is not what happens with btrfs: it would happily continue to write the data on the array until reboot.

And then suddenly it's "oh my god array is degraded!!!111 you should not write to it1111".

To add on that: I never seen for a HW RAID card to stop booting by a mere degraded state of the array. Changes in configuration of arrays, loss of more than enough for redundancy drives - yes, that would halt the boot and require the operator intervention. Array in a degraded state? Just spit the warnings to the console and boot. Nobody has the time to walk to each server with a degraded array on every reboot.