[Scottish] Drive performance...

[Kyle Gordon]

On Fri, 2006-12-01 at 08:37 +0000, Andrew Back wrote:
> On Fri, 1 Dec 2006, Kyle Gordon wrote:

> >
> > Caviar 80GB (Master) + DiamondMax 60 (slave) on the internal IDE controller +
> > Deskstar 120GXP on a PCI Ultra100 TX2 card - giving 120GB
> 
> What configuration gives 120GB from 80 + 60?

Is it not multiples of the smallest drive? Like (n-1)x, n being number
of drives and x being the capacity of the smallest drive?

> 
> > Am I wrong in thinking that the SCSI drives will be faster than the IDE setup,
> > given their age? The DiamondMax is ATA66 whereas the Caviar and DeskStar are
> > ATA100, but the Quantums are Ultra160. The Quantums however, are older, and
> > the primary use of this will be ~, where random access will be preferred over
> > sequential streaming.
> 
> It may not be the case any more given advances in IDE/ATA technology but 
> it certainly used to be that all other things being equal SCSI would win 
> where the workload was of a more random nature. It's bus protocol is 
> (was?) more advanced and allowed command queueing. The OS could send 
> a bunch of requests at the drive and it would be able to service them in 
> the order it saw fit based on where the heads where at. Whereas with IDE 
> everything was serialised and the drive would have to wait for the blocks 
> to pass the heads, service that request, and then take another request, 
> wait for the data to go by the heads and so on.. So SCSI made sense in 
> file servers and multiuser systems, and IDE in the likes of a video 
> editing workstation where access would be largely sequential.
> 
> Of course then you have to factor in drive the performance, cache and so 
> on. And overhead/benefits of disk configuration options - RAID*/JBOD.
> 
> There may be other benefits to SCSI I've missed, and I admittedly know 
> little if anything about modern ATA drives.

I think that settles it then... SCSI it is :-) They may be old, but
still more advanced. On the plus side, it frees up some drives for use
in other machines :-)

Cheers,

Kyle