Re: 12 disks raid setup

On Sat, Mar 1, 2008 at 4:27 AM, Franck Routier <franck.routier@axege.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.