Hi, On Monday 08 November 2010 23:12:57 Greg Smith wrote: > This seems to be ignoring the fact that unless you either added a > non-volatile cache or specifically turned off all write caching on your > drives, the results of all power-fail testing done on earlier versions > of Linux was that it failed. The default configuration of PostgreSQL on > Linux has been that any user who has a simple SATA drive gets unsafe > writes, unless they go out of their way to prevent them. Which is about *no* argument in favor of any of the options, right? > Whatever newer kernels do by default cannot be worse. The open question > is whether it's still broken, in which case we might as well favor the > known buggy behavior rather than the new one, or whether everything has > improved enough to no longer be unsafe with the new defaults. Either I majorly misunderstand you, or ... I dont know. There simply *is* no new implementation relevant for this discussion. Full Stop. What changed is that O_DSYNC is defined differently from O_SYNC these days and O_SYNC actually does what it should. Which causes pg to move open_datasync first in the preference list doing what the option with the lowest preference did up to now. That does not *at all* change the earlier fdatasync() or fsync() implementations/tests. It simply makes open_datasync the default doing what open_sync did earlier. For that note that open_sync was the method of *least* preference till now... And that fdatasync() thus was the default till now. Which it is not anymore. I don't argue *at all* that we have to test the change moving fdatasync before open_datasync on the *other* operating systems. What I completely don't get is all that talking about data consistency on linux. Its simply irrelevant in that context. Andres -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
