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.
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