asus p2b-ds and scsi (from a scsi newbie)

  • Thread starter Thread starter eric
  • Start date Start date
E

eric

Ok, time to get my SCSI-ness together. I've been an IDE person since
I can remember. This would be the first board I've owned with SCSI
capabilities.

The board appears to have two scsi connectors, one for 50 pin and the
other 68 pin. I've got lots of 50pin scsi connectors lying about the
house from some purchas or other I made on E-bay.

Is one option (50 vs 68 pin) better than another? Is there a
difference other than the obvious, the pin count? I have noticed that
there are all sorts of SCSI drives, connectors and adaptors. What are
the differences between them?

Do I need to know anything special about the cables? Would a 7200RPM
scsi drive run faster (to make a real difference) than an ATA100
7200RPM IDE drive? Is it the 40Mhz bus which makes the difference?

How would I go about buying a SCSI drive that would go with this
board? Meaning: are there any special characteristics the drive must
have to work with this board? Are there some SCSI drives which would
not work with this board? Or perhaps they would with the right PCI
SCSI controller card?

lots of questions. If you know of a good teaching link, maybe that'll
suffice.

thanks in advance
 
Ok, time to get my SCSI-ness together. I've been an IDE person since
I can remember. This would be the first board I've owned with SCSI
capabilities.

The board appears to have two scsi connectors, one for 50 pin and the
other 68 pin. I've got lots of 50pin scsi connectors lying about the
house from some purchas or other I made on E-bay.

Is one option (50 vs 68 pin) better than another?
Click to expand...

The 50-pin connector is intended for Narrow SCSI devices up to Ultra
(Narrow) in SE mode. (Mainly opticals and such.) The 68-pin connector
takes Wide SCSI devices up to Ultra2 Wide in LVD mode and Ultra Wide in
SE mode. For connecting contemporary hard drives, the latter is pretty
much the only option, since mainstream SCSI drives have been Wide/LVD
for 4-5 years or so.
I have noticed that
there are all sorts of SCSI drives, connectors and adaptors. What are
the differences between them?
Click to expand...

You will find SCSI hard drives in 3 connector variants:
* Narrow, 50-pin - up to Ultra SCSI, mainly <=1999
* Wide, 68-pin - up to U320 SCSI
* SCA, 80-pin - Narrow or Wide depending on age, unified power/data,
hotswap capable, needs adapter (aggravating at times),
intended for SCA backplanes.

You may also find
* 40-pin Fibre Channel drives - FC is SCSI's "big brother", but not
directly compatible. Req's rather
expensive infrastructure.
Do I need to know anything special about the cables?
Click to expand...

The cable should be one that's certified at least for U2W, better U160
operation and comes with an integrated LVD/SE terminator.
Would a 7200RPM
scsi drive run faster (to make a real difference) than an ATA100
7200RPM IDE drive?
Click to expand...

No, in the contrary it would be slower, at least for desktop tasks!
Compare the performance of the Seagate Barracuda ATA IV and the
Barracuda 36ES2, two drives that basically contain the same mechanics
(for the 20 and 40 gig 'Cuda ATA IV, even the platter count would be the
same) but different electronics. Using storagereview.com's comparison
feature, the result looks like this:
http://storagereview.com/php/benchm...&numDrives=1&devID_0=100&devID_1=211&devCnt=2
The poor 'Cuda 36ES2 is left far behind in all desktop benchmarks, while
in terms of server performance it clearly wins thanks to Tagged Command
Queueing. (Overall the 'Cuda ATA IV holds a slight advantage, probably
because it was a two-platter model vs. the single-platter 36ES2.)
If you go SCSI, you go out and buy a *fast* drive. For current ones,
this would mostly mean 15k (their 10k colleagues frequently ship with
ball bearings and are rather noisy for a desktop, but then who cares in
the server room?), preferably one of the smaller models with 18 or 36
gigs for acceptable noise and price levels. (Their second-gen
predecessors are usually noticeably more noisy, better keep away.) As
for a slightly older, but also pretty quiet drive, take a look at the
Cheetah 36ES - I have an 18 gig one here and like it, actually so much
that I just bought another ;). (It's one of the few 10k drives shipped
with FDBs to date. Only the next generation of 10k seems to feature FDBs
throughout.)
How would I go about buying a SCSI drive that would go with this
board?
Click to expand...

1. Read some reviews.
2. Make up mind.
3. Buy drive. (Recommend current-gen or last-gen used ones.)
;)
Meaning: are there any special characteristics the drive must
have to work with this board?
Click to expand...

No - that's the good thing about SCSI. That's enterprise-level "stuff
that must work"[tm].
lots of questions. If you know of a good teaching link, maybe that'll
suffice.
Click to expand...

While you're at SR, check out the "Reference Guide" link on top of the
page. This should pretty much answer all the remaining questions.

Stephan
 
[snip]
Is one option (50 vs 68 pin) better than another?
Click to expand...
Click to expand...
[snip]

It's not so much "better or worse" as it is "horses for courses". Different
devices will be better-suited for one variant or the other. The thing to
remember is that SCSI is *not* just a HDD interface. It is a general-purpose
peripheral bus. Stephan has given you some good starter info; I only have a
few minor quibbles...
The 50-pin connector is intended for Narrow SCSI devices up to Ultra
(Narrow) in SE mode. (Mainly opticals and such.)
Click to expand...
[snip]

And many tape drives, and (at least older and/or more "serious") scanners, and
a bunch of other stuff.
No, in the contrary it would be slower, at least for desktop tasks!
Compare the performance of the Seagate Barracuda ATA IV and the
Barracuda 36ES2, two drives that basically contain the same mechanics
(for the 20 and 40 gig 'Cuda ATA IV, even the platter count would be the
same) but different electronics. Using storagereview.com's comparison
feature, the result looks like this:
Click to expand...
[snip]

But it's not that simple; and SR's benchmarks are inherently saddled with
"assumption-itis".

Regardless of any particular model-specific comparison, such as that SR test
you pointed to, one of the defining characteristics of the "IDE vs. SCSI"
question is that IDE is a relatively "dumb" interface which requires that the
host system handle most of the I/O "grunt work"; whereas, SCSI is an
"intelligent bus" all its own, which can receive a (relatively high-level)
"order" from the host system, then go off and execute it with little or no
further micro-management from the host. So on a relatively fast host system
which is not otherwise "preoccupied", benchmarks like those used in that SR
article can make IDE look better than it really is "in real life". For a more
realistic test, measure the performance of some other CPU/memory-intensive
application, *while* a large read/write operation is in progress. That's
where you'll see one of the big advantages of SCSI. It gets even more
conspicuous when you get into things like RAID striping/mirroring, etc.

--

Jay T. Blocksom
--------------------------------
Appropriate Technology, Inc.
usenet01[at]appropriate-tech.net


"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
-- Benjamin Franklin, Historical Review of Pennsylvania, 1759.

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Unsolicited advertising sent to this E-Mail address is expressly prohibited
under USC Title 47, Section 227. Violators are subject to charge of up to
$1,500 per incident or treble actual costs, whichever is greater.
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Ok, time to get my SCSI-ness together. I've been an IDE person since
I can remember. This would be the first board I've owned with SCSI
capabilities.

The board appears to have two scsi connectors, one for 50 pin and the
other 68 pin. I've got lots of 50pin scsi connectors lying about the
house from some purchas or other I made on E-bay.

Is one option (50 vs 68 pin) better than another? Is there a
difference other than the obvious, the pin count? I have noticed that
there are all sorts of SCSI drives, connectors and adaptors. What are
the differences between them?

Do I need to know anything special about the cables? Would a 7200RPM
scsi drive run faster (to make a real difference) than an ATA100
7200RPM IDE drive? Is it the 40Mhz bus which makes the difference?

How would I go about buying a SCSI drive that would go with this
board? Meaning: are there any special characteristics the drive must
have to work with this board? Are there some SCSI drives which would
not work with this board? Or perhaps they would with the right PCI
SCSI controller card?

lots of questions. If you know of a good teaching link, maybe that'll
suffice.

thanks in advance
Click to expand...

Hi Eric,

Just a couple of comments to add to the excellent responses so far...

There are actually 3 SCSI connectors on the P2B-DS, one 50-pin and two
68-pin. The 68 closest to the memory slots is UltraWide (40MB/s) and is
intended primarily for external devices - the board originally came with
a cable to extend the connection to the rear panel. The other 68 is
Ultra2Wide (80MB/s) and is the one you should use for fast internal
drives. Again, Asus originally supplied an LVD cable and active
terminator for use on this connector. You must have a terminator on the
end of the cable since LVD drives do not provide termination.

I second Stephan's comments regarding Seagate 36ES drives - I have a
dozen or so of these in total, and find them to be the ideal drive for
P2B-S/DS systems: low noise levels, reliable, and single-drive
throughput is sufficient to almost saturate the 80MB/s U2W bus.
Unfortunately others seem to have figured this out - I'd grown
accustomed to buying used 18gig 36ES drives for around $50, but recent
eBay prices have escalated to more than 3 times that!

www.scsifaq.org is a great place to learn more about SCSI, and
comp.periphs.scsi is the NG to use for questions not answered there.

P2B

http://tipperlinne.com/p2bmod
 
off the basic topic, but,

You know, my first thoughts about the fact that this board comes stock
with the 133 mhz 44mhz pci jumper option was that, well, most of those
server folks are gonna use scsi drives and so it doesn't really
matter. ( I thought to myself) But then, thinking that most folks
were probably using this mobo as a server, we have the problem that
network cards are pretty bad at supporting high pci bus speeds, So
there went that theory, not to mention the AGP bus.

thanks everyone for your contributions to my mental chemistry set.

Oh yeah, I'm a "top-poster". I've been one for several years now,
after we had this debate on the winhome mailing list about it and
several semi-blind folks chipped in that it was far easier for them to
maneuver through the posts if the answers went at the top.

eric
 
Oh yeah, I'm a "top-poster". I've been one for several years now,
after we had this debate on the winhome mailing list about it and
several semi-blind folks chipped in that it was far easier for them to
maneuver through the posts if the answers went at the top.
Click to expand...

Then don't quote back the post you are replying to. In the 21st
century, threaded newsreaders can keep the context together. You're
just wasting bandwidth by increasing the noise.
 
On Thu, 13 May 2004 14:36:28 +0200, in <alt.comp.periphs.mainboard.asus>,
[snip]

Oh yeah, I'm a "top-poster". I've been one for several years now,
after we had this debate on the winhome mailing list about it and
several semi-blind folks chipped in that it was far easier for them to
maneuver through the posts if the answers went at the top.
Click to expand...
[snip]

Only if the articles they're trying to wade through were written by
full-quoting idiots too lazy/careless/ignorant to properly trim the quoted
material to *only* those portions they are directly addressing.

Usenet Hygiene - Dave Learns All About Top-Posting
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Dave: Oh! Now it makes sense to me. Okay!
No more top-posting for me!

Bob: It's annoying because it reverses the
normal order of conversation. In fact,
many people ignore top-posted articles.

Dave: What's so wrong with that?

Bob: That's posting your response *before*
the article you're quoting.

Dave: People keep bugging me about "top-posting."
What does that mean?

[The preceding educational opportunity was provided by Adam Brower.]


--

Jay T. Blocksom
--------------------------------
Appropriate Technology, Inc.
usenet01[at]appropriate-tech.net


"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
-- Benjamin Franklin, Historical Review of Pennsylvania, 1759.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Unsolicited advertising sent to this E-Mail address is expressly prohibited
under USC Title 47, Section 227. Violators are subject to charge of up to
$1,500 per incident or treble actual costs, whichever is greater.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
[REPOST: Apparently, the original copy of this article did not propagate.
Apologies if duplicate.]

On Thu, 13 May 2004 14:36:28 +0200, in <alt.comp.periphs.mainboard.asus>,
[snip]

Oh yeah, I'm a "top-poster". I've been one for several years now,
after we had this debate on the winhome mailing list about it and
several semi-blind folks chipped in that it was far easier for them to
maneuver through the posts if the answers went at the top.
Click to expand...
[snip]

Only if the articles they're trying to wade through were written by
full-quoting idiots too lazy/careless/ignorant to properly trim the quoted
material to *only* those portions they are directly addressing.

Usenet Hygiene - Dave Learns All About Top-Posting
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Dave: Oh! Now it makes sense to me. Okay!
No more top-posting for me!

Bob: It's annoying because it reverses the
normal order of conversation. In fact,
many people ignore top-posted articles.

Dave: What's so wrong with that?

Bob: That's posting your response *before*
the article you're quoting.

Dave: People keep bugging me about "top-posting."
What does that mean?

[The preceding educational opportunity was provided by Adam Brower.]


--

Jay T. Blocksom
--------------------------------
Appropriate Technology, Inc.
usenet01[at]appropriate-tech.net


"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
-- Benjamin Franklin, Historical Review of Pennsylvania, 1759.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Unsolicited advertising sent to this E-Mail address is expressly prohibited
under USC Title 47, Section 227. Violators are subject to charge of up to
$1,500 per incident or treble actual costs, whichever is greater.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
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