Martijn van Oosterhout <kleptog@xxxxxxxxx> writes: > That depends. As long as the data is appropriately sync()ed when > PostgreSQL asks, it should be fine. However, from reading the manpage > it's not clear if fsync() still works when mounted -o async. > > If -o async means "all I/O is asyncronous except stuff explicitly > fsync()ed" you're fine. Otherwise... That's the way it works. Async is the default setting for most filesystems, but fsync() is always honored, at last as far as non-lying hardware will allow. :) > The usual advice is to stick the WAL on a properly synced partition and > stick the rest somewhere else. Note, I have no experience with this, > it's just what I've heard. This might not be optimal, as having every write synchronous actually results in more synced writes than are strictly necessary. -Doug
