On Wed, Feb 21, 2018 at 11:14:20PM +0100, Peter Backes wrote: [...] > atime, in contrast, was clearly one of the rather nonsensical > innovations of UNIX: Do one write to the disk for each read from the > disk. C'mon, really? It would have been a lot more reasonable to simply > provide a generic way for tracing read() system calls instead; then > userspace could decide what to do with that information and which of it > is useful and should be kept and perhaps stored on disk. Now we have > this ugly hack called relatime to deal with the problem. [...]
IIUC, the purpose of atime can be more apparent if you consider it in the context of the time it appeared: the systems were multi-user but the disks were small, so a question "what files are lying there but appear to be unused" was rather sensical to ask as such files could be found, reported and then considered for deletion of moving off rotating media to tapes etc.