Re: [PATCH 4/4 v2] Add documentation for hard disk shockprotection interface

[raz ben yehuda <razb@bitband.com>]

On Fri, 2008-09-19 at 11:50 +0200, Elias Oltmanns wrote:
> [ For some reason your email has not shown up on linux-ide. ]
yes. I noticed too.
> "Raz Ben-Yehuda" <razb@bitband.com> wrote:
> > Elias
> > looks very interesting.
> > 1. How will it impact VM , swappers , raids ?  
> 
> What exactly do you want to know? As long as the disk is parked, you can
> do no I/O on it, i.e. no swapping is possible. Since I don't know
> anything about the implementation of raids and don't have a raid setup
> here, I can't really tell how a raid device will behave exactly when one
> of its disks has been parked. Generally, all I/O will be delayed until
> the disk is unparked again.
> > 2. you said it has no value for servers ? did you try ?
> 
> Again, I'm not quite sure what you want to know. Obviously, desktops or
> servers for that matter can have disks installed that support the unload
> feature. On these devices you can use the interface as described in my
> document. All I'm saying is that the interface has been designed with
> laptops in mind because I don't see in which situation immediate head
> unloading would be required or even desirable in a classical server
> environment.
I will rephrase. does head parking increase reliability ( MTBF ... MTTF ) of a disk ? 
My servers hardly generate IOs at night times, does head parking at nights extend 
the life of a disk ? or is it the opposite ? does it matter ?
thank you again
raz

> Regards,
> 
> Elias