Re: 12 disks raid setup

On Sat, Mar 1, 2008 at 4:27 AM, Franck Routier <franck(dot)routier(at)axege(dot)com> wrote:
> Hi,
>
> Le vendredi 29 février 2008 à 23:56 -0500, Greg Smith a écrit :
> > Wording is intentional--if you don't have a battery for it, the cache has
> > to be turned off (or set to write-through so it's only being used on
> > reads) in order for the database to be reliable. If you can't finish
> > writes after a power off, you can't cache writes and expect your database
> > to survive for too long.
>
> Well, am I just wrong, or the file system might also heavily rely on
> cache, especially as I use XFS ?
>
> So anyway Postgresql has no way to know if the data is really on the
> disk, and in case of a brutal outage, the system may definitely lose
> data, wether there is another level of caching (Raid controller) or
> not...
>
> Right ?

nope. assuming your disk subsystem doesn't lie about write
completion, then postgresql can recover from complete and sudden loss
of power without any data loss.