The default AIO backend requires AIO blocks. On production systems, all
available AIO blocks could have been already taken by ScyllaDB. Even
though the tools only require a single unit, we have seen cases where
not even that is available, ScyllDB having siphoned all of the available
blocks.
We could try to ensure all deployments have some spare blocks, but it is
just less friction to not have to deal with this problem at all, by just
using the epoll backend. We don't care about performance in the case of
the tools anyway, so long as they are not unreasonably slow. And since
these tools are replacing legacy tools written in Java, the bar is low.
Closesscylladb/scylladb#17438
94dac43b2f