4 ms·

Is this because PostgreSQL's file format will become hopelessly confused and unable to restart if flush doesn't work? A lot of applications can lose the last 1

by bbulkow 14y ago

Is this because PostgreSQL's file format will become hopelessly confused and unable to restart if flush doesn't work? A lot of applications can lose the last 100ms of writes, especially if its rare because of a k-safe cluster design, as long as you don't have a corrupted file format. A good transaction log based system will recover - as the author's should.

hosay123 14y ago
It's not only a case of file formats.. a few years ago one of the Linux kernel developers (Theodore Tso IIRC) made a post regarding drive behaviour under power loss, and the results were pretty insane. For example when a rotating drive fails, you might lose +/- 4kb around the previous sector under write, whereas with particular SSDs, he witnessed 1mb chunks zeroed out every Nmb across the entire drive. That kind of thing, you simply can't work around in software
jacques_chester 14y ago
> A good transaction log based system will recover - as the author's should. Unless the drive lies. Tells filthy dirty ugly lies. And lots of them do. OS: "Did you persist that data I flushed?" Disk controller (hiding single copy in RAM cache behind its back): "Oh absolutely, bro. It's tight. Solid. You got nothing to worr-"BZZZT