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  1. #46
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    Re: 6X Raptors overkill?

    Well raptors come in both 8 and 16 meg cache right?

    Any other drives have more then that?

  2. #47
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    Re: 6X Raptors overkill?

    Quote Originally Posted by alex666 View Post
    If you look at that review oral is referring to, the raptor 150 does extremely well. Certainly not outdated technology.

    marty
    Yes, the ADFD's do quite well. They would do a lot better if they had the same kind of density as newer 7200 rpm drives though. As it stands, the best 7200rpm drives are only really lagging behind in tests that strongly emphasise random access.

    Raptors have 3 inch diameter (inner 1 inch taken up by spindel) platters (7200rpm destop drives have ~3.5" platters) that spin at 10000rpm, so there is less track length (9.42 inches vs 11 inches) on the raptor that moves faster. The lower platter width also means less time for the read/write heads to traverse the width of the platter.

    Theoretically this means...

    7,200 / 10,000 = .72
    2 / 2.5 = .8
    .72 * .8 = .576

    ..that a raptor has 57.6% the access time of most 7200rpm drives.

    Since HD Tach shows my drive to have a 15ms access time, that means a raptor should have around a (15 * .576) 8.64ms access time, if other drive and interface components are similar.

    Since the benchmark post BMW made shows a 7.9ms access time, this suggests that my results, base don the pure mathematics of the disk's shape are pretty accurate.

    Now, this math, and most benchmarks, check the entire spread of the drive, from the inner most track, to the outer. Most real world use will not do this.

    There are other things that must be taken into account:

    Several released or soon to be released 7200rpm drives have 250-334GB platters; the raptor has 75GB platters. Because of this, if I put 75GB of stuff on my drive, the actuators only need to move the read/write heads about a third of an inch to cover that data. A raptor would need to move it's read and write heads nearly a full inch.

    Now, at this point the raptor would still be a bit faster, as the track length would still be smaller, and platter is still spinning faster, but even this can be overcome.

    Just use the middle of the platter on a perpendicular recording drive.

    If I make a 75GB partition smack in the middle of my drive, that partition will be faster, in many cases, even where access times are concerned, than the ADFD raptors. Why? I still get 90MB/s transfer rates in the middle of my drive, and I would have reduced the track length and head travel distances enough to compensate for the rpm advantage of the raptor.

    Simple, hard, math. And quite testable as well.

  3. #48
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    Re: 6X Raptors overkill?

    Quote Originally Posted by Poci View Post
    Well raptors come in both 8 and 16 meg cache right?
    Yes, the original models, with a GD suffix, have an 8 meg cache. The newest models have either a ADFD or AHFD suffix, and these have 16 meg caches.

    Any other drives have more then that?
    Not that I am aware of right now, but I do expect that sizes will increase.

  4. #49
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    Re: 6X Raptors overkill?

    7K1000s and a few others have 32MB caches.

    Largely irrellivant except for sequential writes.

  5. #50
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    Re: 6X Raptors overkill?

    Quote Originally Posted by oralpain View Post
    If I make a 75GB partition smack in the middle of my drive, that partition will be faster, in many cases, even where access times are concerned, than the ADFD raptors. Why? I still get 90MB/s transfer rates in the middle of my drive, and I would have reduced the track length and head travel distances enough to compensate for the rpm advantage of the raptor.

    Simple, hard, math. And quite testable as well.
    Sure, and the Raptor can benefit from doing the same thing. Most Raptor users are buying the drive to use for OS and apps. I use only 12GB of mine, which used to be only 6GB each drive before I got rid of my RAID0, and it is all at the outside platter via PerfectDisk.

  6. #51
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    Re: 6X Raptors overkill?

    Quote Originally Posted by oralpain View Post
    7K1000s and a few others have 32MB caches.
    Thanks... I wasn't aware of that.

    Largely irrellivant except for sequential writes.
    Not entirely true. Remember that caches are dynamically sized and segmented on-the-fly, which allows writes to be prioritized and performed at the most opportune time, specifically, after higher priority reads already in the queue, as when loading another app, or calling a DLL file when needed by an already running app.

  7. #52
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    Re: 6X Raptors overkill?

    Quote Originally Posted by tuskenraider View Post
    Sure, and the Raptor can benefit from doing the same thing. Most Raptor users are buying the drive to use for OS and apps. I use only 12GB of mine, which used to be only 6GB each drive before I got rid of my RAID0, and it is all at the outside platter via PerfectDisk.

    But a 12GB partition at the right position of a high density 7200rpm drive would have still faster access times.

  8. #53
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    Re: 6X Raptors overkill?

    Quote Originally Posted by BWM View Post
    Not entirely true. Remember that caches are dynamically sized and segmented on-the-fly, which allows writes to be prioritized and performed at the most opportune time, specifically, after higher priority reads already in the queue, as when loading another app, or calling a DLL file when needed by an already running app.
    I was refering to the physical, on board, drive cache only. You are of course correct when it comes to OS cache.

  9. #54
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    Re: 6X Raptors overkill?

    Quote Originally Posted by oralpain View Post
    But a 12GB partition at the right position of a high density 7200rpm drive would have still faster access times.
    That's true, in theory, the access time could be reduced to spindle latency plus the average t-t seek time of the number of tracks in the partition. 4.5 to 5 ms access time is possible within a small partition on a 7200 rpm drive.

  10. #55
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    Re: 6X Raptors overkill?

    Quote Originally Posted by oralpain View Post
    I was refering to the physical, on board, drive cache only. You are of course correct when it comes to OS cache.
    I was referring to the cache on the drive itself.

  11. #56
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    Re: 6X Raptors overkill?

    Quote Originally Posted by BWM View Post
    That's true, in theory, the access time could be reduced to spindle latency plus the average t-t seek time of the number of tracks in the partition. 4.5 to 5 ms access time is possible within a small partition on a 7200 rpm drive.
    So why spend $150+ on a raptor, when you can get a fast, 250GB, single platter, drive for $62?

    Quote Originally Posted by BWM View Post
    I was referring to the cache on the drive itself.
    Really? Well, you may be right, but I've gone from 2MB cache drive to 8MB ones of the same line and not noticed any difference in windows. Maybe other drives show more of a difference.
    Last edited by oralpain; 08-11-2007 at 06:39 PM.

  12. #57
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    Re: 6X Raptors overkill?

    Quote Originally Posted by oralpain View Post
    So why spend $150+ on a raptor, when you can get a fast, 250GB, single platter, drive for $62?
    Depends on whether one wants fast access time only within a small partition, or over the full span. And of course don't forget about the penalty imposed by having multiple partitions when data in the other partitions is also frequently accessed. That penalty of course must be evaluated by each person individually, after having studied access patterns of the apps being run.

    Really? Well, you may be right, but I've gone from 2MB cache drive to 8MB ones of the same line and not noticed any difference in windows. Maybe other drives show more of a difference.
    That did indeed vary from one manufacturer to another. Back when 8 meg caches first appeared, western digital models showed a more obvious improvement than others, one that one didn't need a benchmark to know that they got. We witnessed the (sort of) revolution that took place right here in this forum during that time. The 800JB created quite a stir here and elsewhere on the web.

  13. #58
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    Re: 6X Raptors overkill?

    Not sure what I was thinking of earlier when I suggested a partition on the middle of the disk, as that would do nothing to rotational latency.

    Quote Originally Posted by BWM View Post
    Depends on whether one wants fast access time only within a small partition, or over the full span. And of course don't forget about the penalty imposed by having multiple partitions when data in the other partitions is also frequently accessed. That penalty of course must be evaluated by each person individually, after having studied access patterns of the apps being run.
    Well, in situations like tuskenraider mentioned, using the drive as a boot/application drive, where are the advantages of a raptor?

    I could, after all, put a 15-75GB partion on one of these ST3250410AS drives and leave the rest unallocated.

  14. #59
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    Re: 6X Raptors overkill?

    Quote Originally Posted by oralpain View Post
    Not sure what I was thinking of earlier when I suggested a partition on the middle of the disk, as that would do nothing to rotational latency.
    Correct, that is fixed.

    Well, in situations like tuskenraider mentioned, using the drive as a boot/application drive, where are the advantages of a raptor?
    It depends on how full the drive is. The more of the available space is used, and the wider the overall access pattern, the more obvious and real the advantages of a raptor's access time become. That pretty much describes most of what an "enterprise" scenario is.

    I could, after all, put a 15-75GB partion on one of these ST3250410AS drives and leave the rest unallocated.
    No argument there, except that windows does force certain files into physical locations on a drive that still make fast access time important, but there are ways to compensate for that as well.

  15. #60
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    Re: 6X Raptors overkill?

    Quote Originally Posted by BWM View Post
    The onboard RAID controllers, depending on whether or not they're on the PCI bus, will outperform a PCI add-on controller. The advantage that a PCI card would have is that it will probably eat up a bit less CPU time.
    So you are saying that the onboard RAID controller on my Asus PC-DL will outperform something like this?

    http://www.newegg.com/Product/Produc...82E16816102076

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