Shame drives can't talk to each other.

John Gay johngay at eircom.net
Tue Aug 31 12:56:34 PDT 2004


On Tue 31 Aug 2004 17:49, Ian Molton wrote:
> On Tue, 31 Aug 2004 18:43:19 +0100
>
> Ian Molton <spyro at f2s.com> wrote:
> > On Tue, 31 Aug 2004 18:22:54 +0000
> >
> > John Gay <johngay at eircom.net> wrote:
> > > While thinking about drives, especially hard drives, DVD's and CD's,
> > > I was thinking. It's a shame that the drives can't be made to talk
> > > to each other over the IDE cable.
> >
> > Buy SCSI. its been doing this for over 12 years
>
Not very enlightening (-;

> To elaborate somewhat...
>
Please do . . .

> this doesnt necessarily mean SCSI is the future.
>
> in the case of two devices transferring data its clearly better.
>
> however when you have 4 or perhaps 6, or 8 devices on the go, you are
> then relying on all 8 devices firmware being well behaved about
> managiing their bus accesses and not hogging the scant resources. Also,
> the *entire bus* and *every device on it* has to be capable of 8 times
> the raw bandwidth of a single device (plus overhead) in order to operate
> without slowdown.
>
Ahh, so SCSI is great because it allows two or more drives to transfer data 
directly, and SCSI is great because it allows upto 7 or 15 devices on one 
bus, BUT, combine both, and you're asking for trouble.

> the SATA approach *used to* be the expensive one, but now high speed
> silicon chips cost less so manufacturing a 'SATA switch' would be
> trivial in comparison to making an entire bus run at eight times the
> transfer rate. also star topology switching eliminates the reliance on
> each devices firmware.
>
SATA 'switch'?!? I've just found out that SATA only allows one drive per 
controller, so it doesn't seem extremely useful to me. But, if I could put 
multiple drives in, I'd re-consider SATA's usefullness.

> Hmm. I think I just convinced myself that (bus hardware based) SCSI
> should die. hehe.
>
> point to point, high speed, serial, links are the *right* way forward.

Well, it seems to be all the rage ATM, SATA, USB, Firewire, etc. . . 

I just love the hardware expertise on this list. It's better than most of the 
magazines I used to get!

Cheers,

	John Gay



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