What I found really interesting is the fact that some specialized database systems (or the ones operating at really huge scales) are starting to skip the filesystem layer completely and work directly with the underlying devices. Or systems that are supposed to be used with specific type of hardware, like exclusively on nvme disks or tailored to nfs or similar concepts. And even traditional systems start to expect very specific things from the filesystems you put them on.
I think these things are happening because everybody wants to be a platform for every type of workload - so as to not lose marketshare or something.
Oracle was bypassing the filesystem to manage its own data at least 20 years ago.
Specializing strategies based on underlying hardware wasn’t needed when everything used spinning rust but now that we have SSD, with different trade-offs, it makes sense.