OFFTOPIC: Cost/Performance SCSI/IDE

OFFTOPIC: Cost/Performance SCSI/IDE

Post by John McKo » Thu, 08 Jul 1999 04:00:00



OK, I'm stupid. Can anyone out there explain to me why a SCSI hard drive
costs about twice as much as a similiarly sized IDE hard drive? Someone
once told me it was due to the SCSI interface being more expensive to
implement. OK. But isn't the actual hard drive (platters, heads, etc)
the same? So the cost would be "hardware"+"electronics". I can understand
the "SCSI electronics" being more expensive than the "IDE electronics".
but that would imply that difference should be about equal. For instance,
suppose an IDE drive cost is $300. $200 is "hardware" and $100 is
"IDE electronics". As similiar SCSI would be, say $500. $200 is "hardware",
because the "hardware" is nearly identical and $300 is "SCSI electronics".
But wouldn't that mean that a $600 IDE should be $500 hardware + $100
electronics. Implying that a SCSI of similiar size would be $500 hardware
+ $300 electronics = $800 total. But the SCSI generally would be closer
to $1200. What is the $400 for?

Am I all wet when I say that the drive "hardware" is nearly identical
for IDE and SCSI? (assuming the same platters & heads and RPM). Does
SCSI require superior "hardware" (platters & heads). It seems to me
that I've seem the same set of RPM values (5400, 7200, 10000). Why
would a SCSI 5400 RPM need significantly superior "hardware" than
an IDE?

Am I all wet when I say that the "electronics" for an IDE drive are
approximately the same regardless of the size of the drive? Do larger
IDE drives require significantly better IDE electronics? The same
questions for SCSI.

Note - I used the above numbers just as an example, I have NO idea
what the real breakdown is. In fact, since the price per megabyte
seems close to a straight line (except in the really large sizes), I'd
guess that the "electronics" cost is insignificant. I hate to be
negative, but it really seems, to me, that the vendors have said something
like: "We'll price IDE at $X per megabyte and SCSI at $Y per megabyte".
Even if this does not match the cost to manufacture.

Well, enough of my ranting. You may guess I want SCSI but can't afford
it.

If you can enlighten me on this, I really would like to know.

John

 
 
 

OFFTOPIC: Cost/Performance SCSI/IDE

Post by Josh McK » Thu, 08 Jul 1999 04:00:00



Quote:>OK, I'm stupid. Can anyone out there explain to me why a SCSI hard drive
>costs about twice as much as a similiarly sized IDE hard drive? Someone
>once told me it was due to the SCSI interface being more expensive to
>implement. OK. But isn't the actual hard drive (platters, heads, etc)
>the same?

You're not stupid. IDE/EIDE and SCSI hard drives are identicle except
for the interface. I use to work at a hard drive manufacturer years
ago. At that time, the only thing that differed between the two was
the interface electronics. The servo, read channel, processor, heads,
disks, case, etc. were identicle. I use to swap IDE boards on SCSI
HDA's and vice-versa. No problems.

Maybe that has changed since then, but I doubt it.

Josh

 
 
 

OFFTOPIC: Cost/Performance SCSI/IDE

Post by Stuart R. Full » Thu, 08 Jul 1999 04:00:00


: OK, I'm stupid. Can anyone out there explain to me why a SCSI hard drive
: costs about twice as much as a similiarly sized IDE hard drive?

While the SCSI interface requires more processing power in the disk drive, the
real reason is that people will pay more for a SCSI drive than an IDE drive.
And, as long as they do, the manufacturer will charge what the market will
bear.

        Stu

 
 
 

OFFTOPIC: Cost/Performance SCSI/IDE

Post by wizar » Thu, 08 Jul 1999 04:00:00



> OK, I'm stupid. Can anyone out there explain to me why a SCSI hard drive
> costs about twice as much as a similiarly sized IDE hard drive? Someone
> once told me it was due to the SCSI interface being more expensive to
> implement. OK. But isn't the actual hard drive (platters, heads, etc)
> the same? So the cost would be "hardware"+"electronics". I can understand
> the "SCSI electronics" being more expensive than the "IDE electronics".
> but that would imply that difference should be about equal. For instance,
> suppose an IDE drive cost is $300. $200 is "hardware" and $100 is
> "IDE electronics". As similiar SCSI would be, say $500. $200 is "hardware",
> because the "hardware" is nearly identical and $300 is "SCSI electronics".
> But wouldn't that mean that a $600 IDE should be $500 hardware + $100
> electronics. Implying that a SCSI of similiar size would be $500 hardware
> + $300 electronics = $800 total. But the SCSI generally would be closer
> to $1200. What is the $400 for?

> Am I all wet when I say that the drive "hardware" is nearly identical
> for IDE and SCSI? (assuming the same platters & heads and RPM). Does
> SCSI require superior "hardware" (platters & heads). It seems to me
> that I've seem the same set of RPM values (5400, 7200, 10000). Why
> would a SCSI 5400 RPM need significantly superior "hardware" than
> an IDE?

> Am I all wet when I say that the "electronics" for an IDE drive are
> approximately the same regardless of the size of the drive? Do larger
> IDE drives require significantly better IDE electronics? The same
> questions for SCSI.

> Note - I used the above numbers just as an example, I have NO idea
> what the real breakdown is. In fact, since the price per megabyte
> seems close to a straight line (except in the really large sizes), I'd
> guess that the "electronics" cost is insignificant. I hate to be
> negative, but it really seems, to me, that the vendors have said something
> like: "We'll price IDE at $X per megabyte and SCSI at $Y per megabyte".
> Even if this does not match the cost to manufacture.

> Well, enough of my ranting. You may guess I want SCSI but can't afford
> it.

> If you can enlighten me on this, I really would like to know.

> John

John;

A couple of things; first I would agree that there is little difference in
hardware from some manufactures (SCSI vs IDE).    However that doesn't mean
you can't get SCSI drives with better durability specs such as MTBF.    This
can also be said about IDE dirves, even from the same manufacture you can get
drifves with differrent durability specs.

Part of the SCSI pricing issue is related to volume, part to stupidity on the
manufactures.

The electronics in a SCSI drives are more intelligent to handle the
protocol.    Generally they have large onboard caches.    Though with the cost
of memory dropping close to zero this isn't always the case on the latest
equipment.     I'm sure the extra development effort required to get the SCSI
firmware correct is also an issue in pricing.    Personally my biggeest grip
isn't the cost of the drives but the cost of the adapter cards.   Here I go
for mother boards with built in SCSI.

For some types of usages a SCSI disk can be much faster than an IDE drive.
Some will pay the extra bucks for the performance.    I don't really believe
that the costs are really twice as much in all cases.    If your machine is
used in such a way that it benefits from SCSI drives then the cost does mean
much.    For many users, sepecially thoose who use there machines basicly in a
single user mode, the SCSI disk add very little value.

HERE IS Dave Low cost high performance machine implementation suggestion:

Buy a motherboard with some sort of well supported SCSI chipset and two
IDE ports.    Put one very fast high performance Harddisks on each of the
IDE ports.    Put what ever else you want on the SCSI port.    For example put
your CDROM burner on the SCSI port, or ZIP drive for that matter.    Generally
you don't get screwed pricing wise on accessories as much as you do on HD.

Thanks
Dave

 
 
 

OFFTOPIC: Cost/Performance SCSI/IDE

Post by r.. » Thu, 08 Jul 1999 04:00:00



> OK, I'm stupid. Can anyone out there explain to me why a SCSI hard drive
> costs about twice as much as a similiarly sized IDE hard drive? Someone
> once told me it was due to the SCSI interface being more expensive to
> implement.

It has nothing to do with that. The problem seem to be the quantities
produced and selled. A couple of years ago the difference in prices
were only mariginal (sometimes the choice of interface was offered at
equal price).

/Lars

 
 
 

1. 2.5.1-pre2 compile error in ide-scsi.o ide-scsi.c

You patch is reverted and I don't think it will cut it,
since I tries this myself and it didn't work out.

BTW>. Anybody out there who managed to make
SCSI gogin on 2.5.1-pre2... I only have PPA ZIP and
IDE-SCSI at my home machine, and both fail with a bad
pointer derefference...
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