Re: Postgresql Performance on an HP DL385 and

Scott,

Do you know how to activate the writeback on the RAID controller from HP?

Steve

On 8/9/06, Scott Marlowe <smarlowe(at)g2switchworks(dot)com> wrote:
>
> On Wed, 2006-08-09 at 16:11, Steve Poe wrote:
> > Jim,
> >
> > I'll give it a try. However, I did not see anywhere in the BIOS
> > configuration of the 642 RAID adapter to enable writeback. It may have
> > been mislabled cache accelerator where you can give a percentage to
> > read/write. That aspect did not change the performance like the LSI
> > MegaRAID adapter does.
>
> Nope, that's not the same thing.
>
> Does your raid controller have batter backed cache, or plain or regular
> cache? write back is unsafe without battery backup.
>
> The default is write through (i.e. the card waits for the data to get
> written out before acking an fsync). In write back, the card's driver
> writes the data to the bb cache, then returns on an fsync while the
> cache gets written out at leisure. In the event of a loss of power, the
> cache is flushed on restart.
>