[comp.sys.ibm.pc] IDE x SCSI drive.

rosa@maui.cs.ucla.edu (Berthier Ribeiro Araujo Neto) (05/17/91)

What is the difference in performance between these two? 
Is it worth to spend extra money in a SCSI drive? What does
IDE stand for?

Thanks in advance,

	--Berthier

PS: These questions have probably been answered here before, and
I apologize for repeating them.

parsons@matt.ksu.ksu.edu (Scott Parish) (05/17/91)

In comp.sys.ibm.pc you write:

>What is the difference in performance between these two? 
>Is it worth to spend extra money in a SCSI drive? What does
>IDE stand for?

There is a nice article about hard drives and controllers in the 
May 91 issue of Compute! magazine.  Briefly, I'll tell you what
the article says:

Disclaimer:  This is summarized from the article, most of it
is directly quoted, some is slightly paraphrased.  You should
read the full article to gain a complete picture of what
type of drive and interface is best for you.


Interface         Transfer Rate        Encoding Method
ST506             250K-750K / sec        MFM or RLL
SCSI              1-3MB / sec            RLL
ESDI              1-3MB / sec            RLL
IDE               1MB   / sec            ARLL

ARRL = Advanced Run Length Limited, allows 50% more data than
       standard RLL and 100% more than MFM.

IDE  = Integrated Drive Electronics, like SCSI, is an interface
       standard that puts some controller functions on the drive
       itself.  IDE, however, only offers ST506 performance.

SCSI = Small Computer System Interface is an interface standard
       that puts most of the controller functions on the drive
       itself.  SCSI also allows as many as 8 devices to be
       daisychained together.

ST506= An interface that supports transfer speeds of about 500K
       per second and is limited to a hard disk of 127MB or smaller.

On SCSI drives:  SCSI's are neat because the interface lets you
daisychain up to 8 devices. [...]  While SCSI is probably a better
interface in the long run, ESDI is currently better suited to
the DOS environment and probably a better bet for now.

On IDE drives:  You can't maintain IDE with software.  You're
not supposed to low-level format it, and in fact the author
has seen a low-level format damage a drive.  IDE is not 
really a standard interface.  In fact one data-recovery firm
reports that there are 25 different kinds of IDE.  There's 
something a bit too disposable about these drives; they're
basically reliable, but you're helpless if they do develop
a problem.  [...]  Right now, be careful.

Recommendations:  (These are not my recommendations, mind you.)
[...]  When buying computers, think twice about IDE drives.  Again
IDE is a good idea, and you'll save a few bucks, but it robs
you of a lot of disk maintenance options.

--
Scott Parish  a.k.a.  parsons@matt.ksu.ksu.edu                                  ----------------------------------------------
"Some people quitely reveal in the manner of the meek,                           Some people shout the way they feel to a radical degree...
 Some people speak with subtleness and don't rely on words at all." -- MWS