On Sat, 2006-03-11 at 12:33 +0100, PFC wrote: > >> each transaction requires a sync to the disk, a sync requires a real > >> write (which you then wait for), so you can only do one transaction per > >> rotation. > > Not according to a conversation I had with Western Digital about the > > > It depends if you consider that "written to the disk" means "data is > somewhere between the OS cache and the platter" or "data is writter on the > platter and will survive a power loss". > > Postgres wants the second option, of course. I assume that for PostgreSQL "written to disk" is after fsync returned successfully. In practice that could very well mean that the data is still in a cache somewhere (controller or harddisk, not in the OS anymore, see also man page of fsync) -- Groeten, Joost Kraaijeveld Askesis B.V. Molukkenstraat 14 6524NB Nijmegen tel: 024-3888063 / 06-51855277 fax: 024-3608416 e-mail: J.Kraaijeveld@xxxxxxxxxx web: www.askesis.nl
