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Data Storage Hardware

SCSI vs. IDE In The Real World 586

An anonymous reader writes "Gerard Beekmans has a really good comparison of the speeds of IDE and SCSI drives up over on Should help put an end to the myth of IDE erasing SCSI's speed advantage." Note that Beekmans' test handicaps the SCSI disk a bit, with interesting results. (DevChannel, like Slashdot, is part of OSDN.)
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SCSI vs. IDE In The Real World

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  • Meaningless.. (Score:5, Insightful)

    by grub ( 11606 ) <> on Monday October 20, 2003 @06:53PM (#7264824) Homepage Journal

    a really good comparison of the speeds of IDE and SCSI drives

    Oh please. With all due respect to the submitter and Mr. Beekmans, this "comparison" ignores all sorts of other factors: write caching, command overlap, rotational speeds, et al ad nauseum. Yes, some of these are mentioned but a comparison such as this should have hard numbers in a table not opinions. Not that I'm suprised or upset that SCSI trounces IDE, but his comparison is virtually meaningless.

    There are many benchmarking suites out there, I'd suggest these be used for the next test to provide some meaningful results.
    • Regardless of the things he ignored... 7 minutes to 1.5 minutes is a huge difference.

      SCSI has it's uses... you don't have to pay for them if you don't want to.
      • Re:Meaningless.. (Score:2, Insightful)

        by grub ( 11606 )

        Regardless of the things he ignored... 7 minutes to 1.5 minutes is a huge difference

        Indeed it is but taking one small test's result and implying that the results can be applied across the board is misleading at best.
      • Re:Meaningless.. (Score:5, Informative)

        by Hoser McMoose ( 202552 ) on Monday October 20, 2003 @08:11PM (#7265622)
        Sure it's huge, but I could get just as big of a difference between two runs using the EXACT same hard drive.

        The tester didn't even bother to check and see if the files are fragmented, let alone checking to see if the files are on the same part of the disk. The original poster was right, this was NOT in any way a "good" comparison.

        If you actually do want a good comparison, head on over to They have compared many different SCSI and IDE drives and have a VERY good grip as to where and when SCSI's performance advantage comes into play.

        Here's a quick and easy way to do things: Click on "Performance Database" at the top of the page, and then do a head to head comparison of a bunch of few SCSI drives and a few IDE drives. This will give you a whole whack of benchmarks. What you'll find is that on desktop applications, a 7200rpm IDE can almost always outperform a 7200rpm SCSI drive and is usually about on-par with a 10,000rpm SCSI drive. But, as soon as you get into their server benchmarks, the SCSI drives wipe the floor with the IDE drives.

        Then it simply becomes a question of whether you run a server or a desktop. Different drives for different markets.
        • Re:Meaningless.. (Score:3, Informative)

          by BrookHarty ( 9119 )
 rocks, I use to check on HD statistics, speed, cpu usage, compare against current HDs. The Benchmarks section is the only place to look for true speeds on HD compared to all brands.

          They have a leaderboard which REALLY shows how HD's compare. One thing I really like is how CPU usage is going down with newer IDE HD's. I always hated how IDE spikes the CPU. Ive always tempted to buy an addon ide raid controller to help smooth out the IDE spikes, but keep the size advantage of IDE. If money
    • Many of these things are done by the hard drive. One of the big reasons SCSI is expensive is because the disks are made much better. That probably makes up most of the difference, but most IDE disks are made to be big and cheap, not fast and reliable. If a hard drive is going to be fast and reliable, it's going to be with SCSI.

      I somewhat agree with your point, but some (most?) of the SCSI-IDE difference is in the physical hard drive.
    • SCSI *is* faster by a good bit than IDE (and SATA is the same interface, really, just fewer wires with fast serializers at each end)

      However, the test is about as bogus and incomplete as the 2.6.0 vs. 2.4.x vs *BSD tests earlier this week.

      Old, crufty files on IDE, all over.
      Good test would move the files to an empty, freshly formatted IDE drive.
      And to an empty SCSI drive (he did just the latter).
      And SCSI will be faster and the test will be better.

      I have mail scattered across a crufty barracuda. It wa

  • by seriv ( 698799 ) on Monday October 20, 2003 @06:55PM (#7264843)
    and SCSI for servers. It is that simple, it will stay that way because of cost, not because of speed.
  • scsi and laptops (Score:3, Interesting)

    by KhanAFur ( 693723 ) on Monday October 20, 2003 @06:56PM (#7264853)
    This article show that scsi drive have a considerable advantage over the same spindle speed of ide drives. Laptops tend to have slower drives. Has anyone considered using scsi drives in laptops?

    Does anyone know fo laptops that use scsi drives?

    • Apple did, but dumped it cause it cost too much even for them
    • Generally speaking the only portable systems with SCSI drives in them in a 2.5" format have been Macs and Unix workstations. For instance I had a Thinkpad (model 750 I think) with a 603e at 133MHz and it had a SCSI drive. And of course as others have pointed out, the old powerbooks had 'em, which is why they could be put into a scsi drive mode. Well, part of the reason anyway.

      This article doesn't show diddly shit, though, except that in one test, two SCSI drives were both faster than one IDE drive. It als

  • Funny, I had the same experiences with older hardware: SCSI always appeared to be faster, subjectively, on a medium load database/web server. I was really impressed about the dimensions (7 to 20 times!); the pure hardware capacity/speed gave no hint.
    • Yes, so what is it that makes the IDE drives so much slower than they theoretically should be? Is it simply the poor design of the IDE chipsets and interrupt structure?

      • This is something I also would like to know, A scsi card is also sitting on the PCI bus so I would not have thought the problem was there. I wonder how SATA discs compare with Scsi.

      • Here's some anecdotal evidence for you. Many moons ago, when CD ROMs were still a rare beast, I had two models of the same dual speed drive on my desk, one IDE and one SCSI. These were state of the art drives at the time. I had a sample disc with a large Video for Windows file - must have been 10MB at least! On the IDE model playback was jerky and the CPU was maxed at 100%, while on the SCSI version the CPU never got above 50% and playback was smooth as silk.

        The reason for this being that SCSI handles

      • This is because SCSI, by defination, is an intelligent bus. In very simple terms, with SCSI, you basically tell the drive to go to sector x, read y sectors, and let me know when the data is available in it's entirety. While waiting for the process to complete, your OS can go about doing something else as it only has to wait for the data to become available (DMA transfered so it just shows up in memory).

        In IDE, the OS has to position the head, wait x sectors, read a sector, save it into memory, go to the

        • by pjrc ( 134994 ) <> on Monday October 20, 2003 @08:58PM (#7265965) Homepage Journal
          Obviously someone has never read the ATA specs... even ATA-2 from the early 90s...

          In IDE, the OS has to position the head, wait x sectors, read a sector, save it into memory, go to the next sector, read again, store again, and so on.

          No. It's NEVER been that way in ATA. Not even the earliest IDE drives. With MFM drives before IDE, and on the Apple ][ and C-64 this sort work was done, but IDE has never been anything like this.

          With ATA (a.k.a. IDE), you write 5 bytes to registers to indicate the starting sector number and the number of sectors you want. Then, you write to the command register to transfer control to the drive and it begins working on your command. All modern systems will (usually) issue the "read multiple" command, which instructs the drive to read many sectors into its buffer and give an interrupt when they are all available in the buffer. This isn't something new. The read multiple command has been in the ATA specs for a long time, and PCs have made use of it since at least the days of Windows95 and Linux kernel 1.0. When the drive has all the sectors in its buffer, it asserts the interrupt pin. The read multiple command comes in PIO and DMA flavor, and if you wrote the DMA version to the command register, a DMA operation happens to transfer all those sectors to whereever you set up the DMA controller to store them.

          SCSI gets most of its advantage from tagged command queuing and disconnection. These features have appeared in the very latest IDE specs, and so far very few ATA drives support them.

    • My old workstation at work, with an Ultra160 drive, outperformed my ATA-100 RAID0 stripeset at home.

      I've upgraded since then, and my workstation now runs four 15,000 RPM Ultra320 drives in RAID5 configuration. It's pretty sweet. Not quite as visibly sexy as the dual 20" flatpanels, though.

      I'm so spoiled.

    • Same experience here too... I have a P166 server with 128Meg RAM, and before it ran just from an IDE disk. It was terribly slow. I later replaced it with an Adaptec 2940UW with an relatively old IBM 18Gig SCSI harddisk. The difference was mindblowing. It was as if I had upgraded the CPU with a P-II...

      It's insane... SCSI is worths it's money... I just don't have the money... ;-)

  • Real world (Score:3, Insightful)

    by someguy456 ( 607900 ) <> on Monday October 20, 2003 @06:57PM (#7264867) Homepage Journal
    In the real world, you must also take into consideration different file size ranges, tree structures, and file systems. Comparing two hd technologies while keeping these factors constant isn't very "real world" to me.
    • by DAldredge ( 2353 ) <SlashdotEmail@GMail.Com> on Monday October 20, 2003 @07:09PM (#7264991) Journal
      And in the REAL real world, the author of this piece discovered that, for his application, the SCSI drive was at least 300% faster.

      Why isn't his test, done with real world data, not a 'real world' test?
    • Re:Real world (Score:5, Insightful)

      by Ed Avis ( 5917 ) <> on Monday October 20, 2003 @07:09PM (#7264999) Homepage
      In the real world, you must also take into consideration cost. A fair test would be to take a budget of $500 and try two setups, one with IDE and one withSCSI, with any leftover cash spent buying as much RAM as possible. Then see which system perfoms better with a variety of benchmarks.
      • Not really. If you move that to $2000 IDE would really suffer. For starters, it's hard to put that many IDE drives on a single machine. Once you do, you will start running out of PCI slots, or PCI bandwidth in a hurry (running out of PCI bandwidth is a good thing in one sense, but only if you are actually utilizing it well).

        You could move to a ATA-RAID card, which would save you some slots, but that starts to get into the SCSI price range.

        Putting extra RAM in the machine is not really fair. You norm

        • Smiking Crack Hmmm ?

          For starters, it's hard to put that many IDE drives on a single machine.
          No it's not, and you seem to know it because you mention it later: ATA-RAID card

          Once you do, you will start running out of PCI slots, or PCI bandwidth in a hurry (running out of PCI bandwidth is a good thing in one sense, but only if you are actually utilizing it well).

          on the PC Mobo architecture, both IDE(SATA) and SCSI controllers are placed on the same PCI bus. So they obviously share the same PCI bandwidt
      • Why? He mentions cost. Obviously, for him, speed is more important than cost. Not everything can be sped up with caching. Your way of doing a peformance comparison has merit too, but it's a different test imho. Please forgive me if I misunderstood you :)
      • Not really, this was a test for top dog, not which is best at an affordable price. If you do want to factor in price (and remember, the price of scsi won't even be noticed by the accountant at places that need it), consider the extra $400-500 the system with the ide drive in it had in terms of hardware value than the other (assuming they both had quality components).

        If you want a real test, get a bottom of the line scsi drive, and bottom of the line IDE, and top of the line scsi and top of the line IDE an
    • It eliminates the all those other variables, leaving only the drives themselves to affect the speed. Of course, whether or not reading a mutt mail folder really depends on drive speed is up to you.
    • It looks just like every other "real world" study paid for by some lobby group.
  • Holy shit. (Score:3, Insightful)

    by Ophidian P. Jones ( 466787 ) on Monday October 20, 2003 @06:58PM (#7264877)
    I can't believe this kind of bullshit gets posted on Slashdot. For those who didn't read the article (and I know you're out there), the guy compared how long it takes to open his maildir file in Mutt on SCSI and then IDE.

    Since it went faster on his SCSI drive, he concludes that SCSI is faster. Wow! How comprehensive!

    If Slashdot keeps this up, I hope they start to get a reputation like (those people are full of shit as well).
    • I can't believe this kind of bullshit gets posted on Slashdot. For those who didn't read the article (and I know you're out there), the guy compared how long it takes to open his maildir file in Mutt on SCSI and then IDE.

      Since it went faster on his SCSI drive, he concludes that SCSI is faster. Wow! How comprehensive!

      Um. Did he claim it was comprehensive? If not, why are you whining?

      Did he show that the actual throughput was higher for the IDE drive in the one test? Yes, he did. Did the SCSI drive finis
      • Um. Did he claim it was comprehensive? If not, why are you whining?
        I can't speak for the original poster, but I'm whining because this article made the front page, along with a summary that describes it as "a really good comparison of the speeds of IDE and SCSI drives".
    • Re:Holy shit. (Score:2, Insightful)

      by MrScience ( 126570 )
      And, he comes to the conclusion that the drive that's physically faster by 40% and has 2x the buffer is (wow) faster!

      Maybe if he compared drives that were closer together, it would be conclusive... but this is pretty pathetic.
      • Did you actually read the article? He first compared a rather OLD and technically (spec wise) inferior SCSI drive to an IDE drive. When the old SCSI was faster he decided to buy a newer SCSI drive, which was even faster.

        No, it was not a very comprehensive comparison. I would have preferred more benchmarks with varying datasets. However, judging from your post you barely even read what was written.
      • Maybe some day they will test a nice 15000RPM SCSI drive against a nice 15000RPM IDE drive. Then we'll really know what's fastest!

        • Re:Holy shit. (Score:3, Insightful)

          by G00F ( 241765 )
          Maybe some day they will test a nice 15000RPM SCSI drive against a nice 15000RPM IDE drive. Then we'll really know what's fastest!

          You mean testing a 10 year old 15k rpm SCSI drive vs a brand new 15k rpm IDE drive?

    • As this "article" painfully demonstrates, we need the ability to moderate things on the front page.

      If the editors cannot distinguish what is trash or what isn't, let the community decide.

      Thank you.
      • If this site really used user-moderation to determine what should show up on the front page, much of the time there wouldn't be much up there. Web sites like these depend on having eyeballs, so the editors need to keep throwing stuff up there. If there's some other more interesting article, people will read those instead. But look at how much time you, and the others who (rightly) hated the article spent reading and then posting about it, and look at how long we spent responding to your posts. And think
  • by Sheetrock ( 152993 ) on Monday October 20, 2003 @06:59PM (#7264881) Homepage Journal
    Besides the speed advantage, SCSI drives also typically last two to three times longer than their IDE counterparts, and generally go through more rigorous testing.

    Tape drives are like this, too. They look the same, they act about the same during the write process, but the cheapie drives that come with some servers will fail to reread the tapes if they're reused as constantly as they are in most businesses (who, on average, reuse the same weekly tapes for a full year or more!). Better to put the money into a DLTtape solution than to rely on what's bundled with the server.

    • by Anonymous Coward
      What if you steal it ?
    • Besides the speed advantage, SCSI drives also typically last two to three times longer than their IDE counterparts, and generally go through more rigorous testing.

      This is absolutely true. Apple used to ship all SCSI drives in their machines and I still have twelve year old Macs that have never had a hard drive failure. The new IDE drives however are a different story. That said, Apple appears to do more quality testing on their hard drives in that since Apple started shipping Macs with IDE drives, I ha
    • At one time, I believed this - but not anymore. Gone are the days of SCSI drives being huge beasts that occupied 2 5.25" drive bays and came with standard 5 year warranties.

      Most of the recent SCSI drives I've seen look like they're manufactured using the same parts as their IDE counterparts, except for different controller circuitry.

      (Take a look at the new Western Digital SCSI drives, for example. You'd mistake them for their Caviar EIDE drives if you didn't check the connector or read the label on them
      • If you actualy run your tape backups on a nightly basis, religiously, you have no business buying anything less than a DLT drive. The DAT drives and all the other cheaper solutions are "consumer-grade", meaning they're only intended for the occasional use (such as doing a full backup right before wiping out or upgrading your hard drive). They'll quickly wear out and break down if you do much more than that with them.

        What about VXA []? We run at least five tapes a week through our VXA-1 drive, and have had a

    • Besides the speed advantage, SCSI drives also typically last two to three times longer than their IDE counterparts, and generally go through more rigorous testing.

      I'd have to look at more recent IDE specs to be sure, but I was under the assumption that scsi drives don't have to jump back to cyl 1 for multi-reads. If this is still true, this could be directly responcible for scsi's longer life.

  • Not an accurate test (Score:3, Interesting)

    by pagercam2 ( 533686 ) on Monday October 20, 2003 @06:59PM (#7264882)
    The document lists one and only one case. I don't doubt that SCSI has performance benfits that is pretty well known. I've always wondered why they don't upgrade IDE with a better command set much like SCSI, well they haven't they just increase the clock speed and offer better buffering. So there is a valid case for a comparison between SCSI and IDE. This review does one and only one test which proves that SCSI wins on one test this is not a good article. He reads one and only one file. The real question is how well IDE and SCSI operate under real multi-treaded OS conditions. Slashdot editors should be rejecting this article in favour of one with a real indepth analysis. SCSI will win but not for the reasons listed in this article.
    • He reads one and only one file.

      No, he read 50,000 files.

      every email message is stored in a separate file....I used a maildir folder containing 50,000 emails.

      Sure it would have been better for him to run a number of scenarios, but he couldn't build himself a whole lab due to cost factors. Even with this rudimentary testing, a difference of 8 times indicates to me that there is an effect.
    • by pjrc ( 134994 )
      I've always wondered why they don't upgrade IDE with a better command set much like SCSI,

      ATA-5 added multiple command queuing and disconnection (the primary benefits of SCSI). A few drives today support it. Someday, almost all will.

      Tagged command queuing and better drivers in linux are most likely the reason the SCSI drives were able to read 50000 files much more rapidly than a similar IDE drive.

      well they haven't they just increase the clock speed

      DMA modes 0 -> 1 -> 2, followed by UDMA 66 -

  • ...I want Fibre Channel, baby!!! Amateurs. ;-)
  • by Aardpig ( 622459 ) on Monday October 20, 2003 @07:01PM (#7264908) the original creator of Linux From Scratch [], and therefore registers very high on all standard 7331-meters

  • And compare serial drives to serial drives.
    I would have loved to see that SCSI against an SATA150 drive.
  • The Maxtor was 40gb
    The Atlas was 9gb

    The Atlas obviously had less tracks too seek through than the Maxtor because it had 1/4 of the total number of tracks the maxtor did. This would totally account for the 1/3 speed increase seen over the IDE solution.

    Also to take into consideration is how much buffer each drive has. If I remember right, Atlas's have like 8 megs of buffer, while the 40 gig maxtors have like 2.

    • Funny! I read your post and milk came out of my nose.
    • What on earth are you talking about? The drive size has almost no relevance to this test. He was testing reading through 50,000 files, not one huge contiguous file (where tracks might have some bearing).

      Look at the seek times, that is pretty much all that matters here. Every file is going to be a seperate seek. The first SCSI drive had a 6.3ms seek time, which is ~30% faster than the IDE hard drives 8.9ms; however, the actual performance difference is over 600%!
    • Re:Unfair comparison (Score:3, Informative)

      by fishnuts ( 414425 ) *
      The number of tracks a drive has is inconsequential to the access time. The time it takes for the read/write head to move across the platter (since the platters in ide and scsi drives are nearly the same size) is a product of how heavy the heads are and the strength of the motor assembly (which is actually a pair of coils moving between two very strong magnets). I'm inclined to believe that the IDE drive's slower seek performance is actually because if a cheaper head/motor mechanism. After all, the IDE d
  • The issue I've been dealing with is network performance. I set up a new SAMBA server, outfitted with 160 GB RAID, 2 GHz Celeron, and gigabit ethernet; the performance sucks. I get about 120 Mbps max transferring large files. Yes, the client machine is a fast machine too, but I've read that I should be getting 500 Mbps or more. I've checked everything and I have no idea what could possible wrong.

    Anyways, it seems that network performance has always been more of a bottleneck than hard drive performance.

  • I can't believe how short sighted and obtuse this articles is. But you know what really burns my ass? A flame about this /points at buttocks/ high!


  • He's comparing different priced setups. An IDE RAID setup of equal cost and capacity to the SCSI would probably have faired much better in the benchmark.
  • Oh, come ON. (Score:4, Insightful)

    by SlashChick ( 544252 ) <erica AT erica DOT biz> on Monday October 20, 2003 @07:14PM (#7265043) Homepage Journal
    That "benchmark" was ridiculous. "I have this two-year-old IDE hard drive and I'm going to benchmark it against this SCSI drive. Woop, look! It read my mail directory faster! SCSI must be better!"

    Look, I'm not denying that SCSI is faster. But he neglected to even do any other tests! He also neglected to use a newer IDE drive, which hampered the IDE performance dramatically. (Who's going to use a 2MB cache IDE drive in any area where hard drive performance is critical?)

    Personally, I'd like to see the test of an IDE RAID array running off a 3Ware card. For the price of one SCSI drive, you can get 3 8MB cache IDE drives, plus the 3Ware card. Oh, sure, it will probably still be a bit slower than SCSI. But at least the benchmarks will show some sort of logical comparison (and the benefit of IDE -- namely, tons of disk space.)

    Is it just me, or have the articles posted on Slashdot recently been pretty lame? I just don't understand how some of this stuff gets posted to the front page. This is not a review. This is not a benchmark. It's one guy who tested one application of hard drives and made a conclusion based on that test. This type of stuff can be found in any newsgroup or forum on a daily basis. It should not have been posted to the front page of Slashdot.
    • of course its not a real review/benchmark.. look at the reasons for the test.. he plainly states:
      "before my wife would allow me to"...

      the whole point of the testing was to convince his wife to let him buy one.. and she most likely was asleep at "integrated IDE controllers".. apon waking up, all he had to say was "From my testing I concluded that SCSI being faster than IDE is not a myth. It is very much a reality." and obviously got the go ahead

      remember, in the immortal of homer simpson "facts, schmacts...
    • Okay, I know it's bad form to reply to your own post, but I thought I'd add the results of a little Pricewatch search I ran.

      I said in my earlier post that you can get 3x8MB cache drives plus a 3Ware IDE RAID card for about the cost of one SCSI drive. Here are the actual cost breakdowns. All prices include shipping.

      1 x 3Ware 7500-4 4-port RAID card: $250
      3 x Western Digital WD800JB hard drives (IDE; 80GB; 8MB cache) = $219.

      TOTAL for IDE system: $469.
      Total usable space: 160GB.
      Bonus points for R
      • Why use a U320 card if all you plan on connecting is one drive?

        The bus bandwidth only comes into play if you have more than 4 disks on the SCSI bus. The max sustained bandwidth of a 10k RPM SCSI disk is ~70 MB/s. You would need a U320 controller if you plan on putting about 4 of these disks on the same bus that is 4x70 MB/s = 280 MB/s.

        You could get away with an LSI logic single chanel U160 64 bit PCI controller for $46.75 shipped (pricewatch). Maxtor 10K rpm 73GB U160 drive can be had for $147 shipped.
  • I smoke cigars, and feel just fine.

    My coworker eats life-savers, and has been diagnosed with skin cancer.

    I conclude from this experiment that life savers cause cancer, but cigars are ok.
  • Single user, single machine, single disk, single transaction? IDE performs ~equal to SCSI, and at a fraction the price.

    Multiple simultaneous transactions is where SCSI wins. Try comparing SCSI vs. IDE for something like an NFS server, and watch SCSI leave IDE in the dust.
    • No, it doesn't. Work with SCSI and you will know that beyond a doubt, it is faster than IDE at every turn. IDE is great for low cost options, but cost is the only attractive thing about IDE drives.
  • by Malor ( 3658 ) * on Monday October 20, 2003 @07:22PM (#7265132) Journal
    He tested a 40gb IDE drive versus a 9gb SCSI drive, both 7200 RPM. The SCSI drive was a lot faster, but this isn't any particular shock; this is pretty old hardware.

    Basically he just told us that circa 2001, SCSI was faster. I think we mostly knew that already.

    It would be a lot more interesting to see the test run with one of the 36gb WD Raptors. They are 10K RPM and are *very* fast drives. I use a pair of them striped as RAID 0 in my main desktop; they're faster than anything I've ever used before, including 10KRPM SCSI. (I haven't used 15KRPM SCSI, which I imagine is probably faster still, but very noisy, which is why I went with the Raptors. )

    Note also that IDE drives in general are "tuned for desktop usage patterns". I'm not entirely sure what that entails, but I suspect it involves a lot of read-ahead caching; single-user systems tend to be actively reading only one or two things at a time. SCSI is tuned for server performance, and the test of "read lots of small files" is probably much closer to a "server" load than to a "desktop" load.

    What I'd like to see is testing of streaming performance in working with really big files. That's something I do fairly frequently. How fast can you extract, say, a 500MB RAR file back to the same disk? How fast is it if you're reading from one and writing to a second? On a personal basis, I do that a lot more than putting 50,000 files in a directory and then reading every single one of them.

    However, if I ever DO plan on putting 50,000 files in a directory and then reading all of them on a frequent basis, I'll be sure to choose SCSI. :-)
  • It really seems to me that the entire point of this "test" was to flaunt his new SCSI drives. I suppose some people feel the need to justify their purchases to a large audience in order to feel they didn't get a bum deal. Well done I say! Enjoy your badass drives and rest assured all the geeks from here to Babylon are impressed.
  • Seems like a pretty lame set of tests and results for this to actually get published. Would it have been *that* much more trouble to at least run a couple of the openly-available and easy-to-find disk benchmarking suites against both disks??

    Sheesh....come on can do better than this.
  • Even though the IDE drive was on a system with a CPU running at three times the speed of the SCSI drive's system, the SCSI machine took only 1/6 as much time.

    I stopped really caring at that point. I woulda thought somebody comparing the virtues of SCSI vs IDE would know that clock speed != processor speed. Redirect all posts about how he didn't count how fast the processor can crunch numbers in his (rather weak) comparison to /dev/null.
  • Holy war? (Score:5, Interesting)

    by BenjyD ( 316700 ) on Monday October 20, 2003 @07:31PM (#7265222)
    What is this? Holy war week on Slashdot? In the last week or so we've had stories on BSD vs Linux, Linux vs Solaris, PHP vs Java, Exchange vs Sendmail , x86 vs PPC and now IDE vs SCSI. All that's missing is Vi vs Emacs and I think we'll have pretty much every major computing disagreement covered.
  • These results and many of the other poster's anecdotal evidence suggests that SCSI drives would make good swap-space drives. The smaller maximum affordable capacities of SCSI would be OK for swap space use too. Has anybody tried doing that?

    (I know, I know, real /.ers just buy more RAM.)
  • or U-can with Beakman and Jax in the newspaper. That's what I thought of. Sort of a successor to Mr. Wizard, but a precursor to Bill Nye the Science Guy.
  • There is simply no way you can get 7x difference simply by switching an IDE HD to SCSI with similar specs. I always get suspicious when I see more than 2x difference. There must be something else. Either something is misconfigured or it is not an apples to apples comparison. Notice that the tests were performed on two completely different machines. The hardware and software configurations were not listed. Which versions of the kernel were the two machines running? Which versions of mutt? Which file systems?
  • by op00to ( 219949 ) on Monday October 20, 2003 @07:47PM (#7265367)
    From the is-this-worth-wasting-the-time-on dept:

    My Pentium 4 is faster than my Apple ][. I did benchmarks!!!!!!!
  • by darkwiz ( 114416 ) on Monday October 20, 2003 @07:47PM (#7265370)
    One would expect the SCSI drives to consistently wallop similarly configured IDE drives (same buffer, spindle, size, #heads and every other physical characteristic you can think of) based solely on one observation: Tagged Command Queuing.

    TCQ allows a drive to execute commands out of order to optimize the access pattern. This can have a HUGE impact on performance. Relatively few drives support TCQ on ATA, and very few chipsets support it as well. This is mostly because people who buy ATA aren't *real* performance freaks. They want high streaming performance (like hdparm -tT), but don't know to care about random access performance as it may not be relevant to them.

    Server/database access patterns are far more random than typical desktop usage, and this is where SCSI wipes the floor with ATA.

    Some have pointed out that RAID enclosures are moving towards IDE drives. This is due to the fact that the integrators are using optimizing logic in the controller to handle emulating TCQ. So you can have a stone-dumb drive in there and it doesn't matter as long as the physicals are there.

    SCSI drives also typically come with caching algorithms which are intended to try to increase cache hits by using more intelligent cache allocation and predictive reading.

    Combine that with better, more intelligent controllers, command detachment, and infinitely better bus sharing - and SCSI cannot be compared to ATA in high demand situations.
  • But *why*? (Score:3, Informative)

    by pla ( 258480 ) on Monday October 20, 2003 @07:49PM (#7265396) Journal
    I have done similarly-informal tests myself, with comparable results.

    I can't say I understand why SCSI performs so much better than IDE, however. In this particular test, he compared what amount to evenly-matched drives, specs-wise, and even gave the IDE drive the better machine. Yet, the SCSI drive completely crushed the IDE drive, no question about it. And as I mentioned, my own informal tests have shown the same results.

    What explains the difference? Same spindle speeds, similar read rates (both buffered and unbuffered), similar seek times... What other factors exist that make so much of a difference? Just higher quality controller hardware? And if so, would an IDE drive on a high-end controller perform comparably?

    Personally, I'll still take 4x the size for the same price, since cost and size (with "okay" performance) matters more to me than raw speed. But I wish I knew why one performs so much better than the other.
  • by vlad_petric ( 94134 ) on Monday October 20, 2003 @08:02PM (#7265544) Homepage
    The main difference is how the bus deals with transactions. SCSI is a split transaction bus, which means that you tell the drive - give me D, A, C, B (in a non-blocking way). The drive will give you back data in the order it finds more convenient (let's say A, B, C, D if it were at one end of the drive) - it effectively rearanges the requests/responses. The operating system already does that to some extent (elevator algorithm), but the OS can't do a better job than the disk controller itself. This is very crucial for servers, where multitasking happens a lot (clearly mutt won't see any difference)

    The second - CPU utilization. A SCSI controller does a lot more work by itself than an IDE one - therefore it requires much less interaction with the CPU.

    Then we have the bus bandwidth - this is probably no longer an issue, as ATA/66/100/133 can pipe enough bytes per second

    Finally, the most important one - manufacturers simply don't make a 10k RPM hardrive IDE drive ... And 10k - 7200 makes a hell of a difference.

  • by spinkham ( 56603 ) on Monday October 20, 2003 @09:44PM (#7266252)
    Check out
    Great drive reviews, the best out there..
    At the moment, the best scsi drive has about a 2x lead over the best IDE drive in "Server style" loads, and about a 20% lead in desktop type loads.

    Note that this really isn't an interface issue, but a market issue. With tagged command queuing in serial ATA, one of the main reasons for SCSI's dominance is gone. Unfortunatly, no enterprise class drives support it yet.

    The difference between SATA and SCSI is market.
    The fastest SATA drive goes for $160, while the fastest SCSI for about $700.

    SCSI drives are manufactured for the "no compromise" audience, and are therefore traditionally faster and more reliable.
    SATA puts IDE drives in the same interface class as SCSI, and more "enterprise class" drives are starting to be built with that interface.

    Given a well-built SATA drive that includes all the SATA features like TCQ and drive with the same build quality in SCSI, I bet that the difference would be minimal. There are no comparable products at the moment though, so time will tell..

If it's not in the computer, it doesn't exist.