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

Discussion in 'Asus' started by eric, May 8, 2004.

  1. eric

    eric Guest

    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
     
    eric, May 8, 2004
    #1
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  2. eric

    Lil' Dave Guest

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  3. 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.
    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.
    The cable should be one that's certified at least for U2W, better U160
    operation and comes with an integrated LVD/SE terminator.
    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.)
    1. Read some reviews.
    2. Make up mind.
    3. Buy drive. (Recommend current-gen or last-gen used ones.)
    ;)
    No - that's the good thing about SCSI. That's enterprise-level "stuff
    that must work"[tm].
    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
     
    Stephan Grossklass, May 8, 2004
    #3
  4. [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...
    [snip]

    And many tape drives, and (at least older and/or more "serious") scanners, and
    a bunch of other stuff.
    [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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    Jay T. Blocksom, May 12, 2004
    #4
  5. eric

    P2B Guest

    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
     
    P2B, May 13, 2004
    #5
  6. eric

    eric Guest

    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
     
    eric, May 13, 2004
    #6
  7. eric

    Ronald Cole Guest

    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.
     
    Ronald Cole, May 15, 2004
    #7
  8. On Thu, 13 May 2004 14:36:28 +0200, in <alt.comp.periphs.mainboard.asus>,
    [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.
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     
    Jay T. Blocksom, May 28, 2004
    #8
  9. [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]

    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.
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     
    Jay T. Blocksom, May 30, 2004
    #9
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