On Wed, Nov 07, 2018 at 08:08:41PM -0500, Fulko Hew wrote: > old brain remembers ... sync; sync; sync; Yep, that was the mantra. > Supposedly, > #1 for the data blocks, > #2 to ensure the updated inodes got written, > #3 to ensure that superblock updates got written (if necessary). Well, that wasn't so. I was doing Unix internals at Bell Labs in 1980. Sync flushed all pending disk I/O operations for the entire kernel ...that's all processes and *all users* on a multi-user machine. The idea was apparently that multiple "syncs" would assure flushing operations that would get submitted; even then it was a bit of apocrypha. However, the early days *were* interesting; BTL was pushing Unix hard by 1980, especially for the 5ESS project, and more people than had ever been using a Unix system concurrently were on the development systems. One week started out badly for us; for some reason everyone was experiencing *incredibly* poor performance. We figured out that we were all on the same server, but the poor guys in the data center couldn't see anything wrong; it was just, suddenly, and inexplicably ***slow***. I was chatting with a new hire who'd started that morning, and he proudly showed me a vi macro he'd written to "guarantee that he never lost data". Really? Let's see...hmm...every command issued was intercepted...AND CALLED SYNC. On a machine hosting a boatload of other users. He was calling sync for every single editor command he typed. Cluebat applied, macro removed, life returned to normal. (And no, I don't know when they stopped letting a single user do that to the whole system, and lost access to Unix source when I left the Labs Way Back When, but they *must* have, right? And no, I've not cared enough to go see how Linux does it.) Cheers, -- Dave Ihnat dihnat@xxxxxxxxxx _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx
