1) 100% yes 2) yup 3) Frequently read/written files will be stored in ram 4) This still affects DBs, as they are still a layer above the FS. 5) GPFS, GFS2, ceph

1) 100% yes 2) yup 3) Frequently read/written files will be stored in ram 4) This still affects DBs, as they are still a layer above the FS. 5) GPFS, GFS2, ceph, cleversafe, tahoe-lafs, all make this go away. 6) ZFS has snapshots. Snapshots are amazing. Granted they are not nice as SQL dump. 7) If you're doing this with files, you're in trouble. Having said that, your last point is 100% valid. Don't reinvent the wheel. SQL is good for most things. Even SQLite is super awesome for slightly busy websites(depending on how you use it).