"Poor" man's NAS

[Bill Campbell]

On Thu, Jun 08, 2006, Alma J Wetzker wrote:
...
>I really doubt that the media and heads are any different between SCSI 
>and IDE (That really is the choice, even though both now have serial 
>options and speeds have improved.)  Is the rest of the drive different? 
>  I don't know.
>
>The electronics, that I understand.  SCSI is still smart.  IDE is still 
>rather stupid.  (IDE includes ATA and SATA)  IDE drives have all the 
>useful stuff built into the controller.  The only do exactly what they 
>are told, and only in that order.  SCSI, OTOH, takes all the commands, 
>evaluates them and does them in the order that optimizes returning 
>results based on what the drive mechanics need to do.  The performance 
>difference is noticeable.

There's a significant difference in quality between drives built for PCS
(desktop systems) and ECS (Enterprise systems).  Drives built for PCS are
designed primarily for minimal cost, while drives for ECS are designed for
reliability and performance.  The whitepaper below is a couple of years
old, but the basics haven't changed.

http://www.seagate.com/content/docs/pdf/whitepaper/D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf

SCSI drives have always been considered enterprise drives, and built for
reliability and performance.

There are enterprise class SATA drives (e.g. WD Raptors), which cost
significantly more than the garden variety commodity drives, and typically
have capacities that reflect the different geometry.  Thus the 10,000 RPM
WD Raptor we just installed has a 74GB capacity while the commodity drives
are generally multiples of 20GB.

Bill
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