Re: io performance...

[Max Waterman]

Jeff V. Merkey wrote:
> Max Waterman wrote:
>
> > Jeff V. Merkey wrote:
> >
> > > Max Waterman wrote:
> > >
> > > > One further question. I get these messages 'in' dmesg :
> > > >
> > > > sda: asking for cache data failed
> > > > sda: assuming drive cache: write through
> > > >
> > > > How can I force it to be 'write back'?
> > >
> > >
> > >
> > >
> > > Forcing write back is a very bad idea unless you have a battery 
> > > backed up RAID controller.  
> >
> >
> > We do.
> >
> > In any case, I wonder what the consequences of assuming 'write 
> > through' when the array is configured as 'write back'? Is it just 
> > different settings for different caches?
>
>
> It is.  This is something that should be configured in a RAID 
> controller.  OS should always be write through.

Ok, thanks for clearing that up, though I now wonder why the message is 
there.

<shrug>

Max.

> Jeff
>
> > Max.
> >
> > > Jeff
> > >
> > > > Max.
> > > > -
> > > > To unsubscribe from this list: send the line "unsubscribe 
> > > > linux-kernel" in
> > > > the body of a message to majordomo@xxxxxxxxxxxxxxx
> > > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > > > Please read the FAQ at  http://www.tux.org/lkml/

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/