My understanding is btrfs will perform poorly with use cases such as
large databases that have a large amount of random reads/writes. As
such, the nocow attribute is usually suggested to allow overwriting to
help reduce fragmentation that would otherwise occur (bearing in mind
the downsides of using the nowcow attribute).

The autodefrag mount option however, helps mitigate this problem
somewhat with smaller databases that may have lower traffic and are
smaller in size, but can be a problem for large files. I assume
because it results in some sort of write amplification?

So my main question is in regards to a filesystem where you may want
to have autodefrag enabled, but also plan to use a large database as
well that may warrant using nocow for the reasons above. Is it okay to
set the nocow attribute while also having autodefrag turned on, or
will autodefrag still be an issue? If so, is it possible to disable
autodefrag on a particular subvolume or to set an attribute to disable
(or enable?) it, or if not, is this planned?  Am I misunderstanding
something here?


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