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Hardware

Attaching IDE Disks to SCSI Controllers? 23

Posted by Cliff from the dogs-and-cats-LIVING-together dept.
A not-so Anonymous Coward brings this query to the forefront: "A German company has an adaptor that will allow you to use cheaper IDE drives with SCSI controllers. There is also another company selling RAID enclosures that look LVD but take IDE disks internally. Raptor RAID is the name, but I can't find the actual company's web page. I did find This review. Anyway, how do these things work, and does anyone make adapters so an individual can attach an 80gig IDE disk to their LVD chain and save $500+USD per disk."
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Attaching IDE Disks to SCSI Controllers? More

Attaching IDE Disks to SCSI Controllers?

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  • err... (Score:3)

    by Wakko Warner ( 324 ) on Thursday June 07, 2001 @04:40AM (#169946) Homepage Journal
    ...you just pointed us to the website of a company who makes products that convert IDE hard drives to SCSI.

    Then you ask us if you know of a way to convert IDE hard drives to SCSI.

    Is this some sort of trick question? If we lose, do we get thrown off the bridge?

    --
    Forget Napster. Why not really break the law?

  • I don't believe the RAID stuff changed much between 2.2 and 2.4, FWIW, so the instructions should largely hold true.

    Also, there's KT-7 RAID MB which supports ATA-100 and Athlons. In that, you can set up mirrors or stripes as you want. Buy a couple of identical HD's and you're set.
    --

  • Ah; I'd thought that this was done at a BIOS level, but of course, linux will go below that to read the disks.

    That said, the software RAID options within linux are still valid, and if you're mirroring, the performance impact shouldn't be much (indeed, reads should be faster if using round-robin).
    --

  • Absolutely. I don't mean to say that there is anything wrong with IDE...I have a SCSI controller sitting around in my compuer room because I have nothing to plug into it - all my drives are IDE. However, the guy would be better off spending the money to get a native IDE controller rather than spending monty on hacks to make his IDE drives work on his SCSI controller.


    This space for rent. Call 1-800-STEAK4U

  • Why pound the square peg into the round hole. (Score:4)

    by TBone ( 5692 ) on Thursday June 07, 2001 @05:42AM (#169950) Homepage

    You want to use a moped to pull an RV. Use the correct tool for the job.

    IDE is an end-user driven and targeted technology. It's cheap, as you see in the proce difference between IDE and SCSI drives. However it's also cheap. The protocol is not as robust, or expandable, or bulletproof. IDE is meant for home users who need lots of space but aren't as concerned about reliability.

    SCSI is a business, server-targeted technology. It's a stronger, faster, more expandable technology. It's meant for stacking ridiculous abouts of space into small areas. It's intended for corporate applications where you need wide data paths to move lots of data very quickly, or need redundant pathing, or lots of other motivations that 99% of your home users don't need. Regardless of how much data you THINK you move, you have not moved data until you start running systems that load 2G datafiles into a Data Warehouse multiple times a day.

    Get an IDE controller that supports the 3rd/4th channel, and quit screwing around with silly adaptors that are a hack to a problem that's trivial to fix if you use the right tools.


    This space for rent. Call 1-800-STEAK4U

  • Yes, I just bought a KT-7 RAID. Too bad it doesn't have drivers for Linux. When the BIOS is set to stripe the disks, Linux only sees one of the drives (that is, I've got 2 45GB hard drives, and I only have 45 GB available--with RAID 0 (striping), the two drives *should* appear as one drive, but be twice as big).

    Sorry, but the KT-7 RAID won't work if you're looking to RAID your drives under Linux. That is, until Highpoint releases Linux drivers for their RAID chipset.
  • Here's a link [highpoint-tech.com] to their support page. My KT-7 RAID, at least, uses the HPT370 chipset. From the web page:
    Note: At this time, the HPT370 Linux patch is compatible with single disk functions only. (Non-RAID)
  • I found this page when I was doing roughly what you describe:

    Linux IDE Raid [att.com]

    I actually corresponded with the guy somewhat, he's very scientific, knowledgable, and motivated to make it work (its his job) so his results are credible.

    I followed the pattern and now have a tower with 2 IDE channels on the mobo, 2 promise cards, and two cards with CMD IDE chips in them. I have a couple of CD drives as hda and hdb, then 9 81GB Maxtor drives, each one as the master disk on a primary or secondary interface.

    Then I used software RAID 5 on Linux-2.4, and believe it or not (I haven't run the tests in a while, but they were rigorous), I can nearly saturate my 100baseT network with data while reading, or store data quickly enough to keep up with the network. Formatted with ext2, this is a 614GB array.

    It looks like the page has been updated recently though, as the I75Raid machine he was working on (>1TB) now has screaming performance, where he was having some problems before.

    Other than hot-swappable hard drives, there's simply no reason to pay for SCSI any more, that I can see. This guys performance looks like it stand up to a 1000baseT network and not suffer too badly.

  • Bridge Boards (Score:4)

    by Detritus ( 11846 ) on Thursday June 07, 2001 @01:17AM (#169954) Homepage
    These things have been around for a long time. Back in ancient times, many SCSI drives were actually ST-506 or ESDI drives with a SCSI bridge board bolted on top. Similar boards are made today to convert IDE drives to USB or FireWire.

    Be aware that an IDE drive with a SCSI bridge board is unlikely to be as fast or reliable as a native SCSI drive. SCSI and IDE drives are designed with different goals.

  • I've actually heard, from an Adaptec technical rep, who would by definition have an interest in seeing you buy SCSI, so take it how you will, that the only major difference with IDE and SCSI is that the SCSI drives did better in QA and had a higher MTBF, so they got SCSI connectors and boards, and the not-as-good drives got IDE connectors and boards. Again, Adaptec rep.

    I do however remember similar stories about Western Digital when their drives REALLY sucked (I've still never ever used one in my machines), back when 540MB was good and 2GB was HUGE, that the drives that went through QA were "Caviar"s and the drives that just got dumped off the line into boxes were their regular model.
  • Last time (okay, the only time) I had experience with IDE RAID was in '94 on BSDi. Since then, I've dealt with SCSI raid for plenty of servers, mostly Novell, WinNT, AIX and Solaris.

    Now I'm looking vaguely at expanding my MP3 jukebox/server to add DivX ;-) capabilities. To do so is economical (100 movies or 400 episodes of Anime per 50gig IDE drive), but only really using IDE equipment. I'd love to find a Linux compatable solution, either software (which I'm vaguely aware exists) or hardware (PCI Card or somesuch).

    Any good pointers to... ahem... recent information? It seems most HOWTOs start out warning you that you will have to upgrade to that newfangled 2.2 kernel. Since I'm already happily using 2.4 on ReiserFS, I'd be interested in a modern, inexpensive (this ain't a mission critical server) solution.

    --
    Evan

  • Tom's Hardware talks about the Promise IDE RAID controller here...

    http://www6.tomshardware.com/storage/00q1/000329/ [tomshardware.com]

    Lately, I've seen mailing list chatter to the effect that academic environments are starting to use IDE RAID in their servers, i.e. those poor bastards are always underfunded. Most of them seem happy, but I don't recall which products they mentioned.

    One thing for sure, the price can't be beat.
  • "It's cheap, as you see in the proce difference between IDE and SCSI drives."

    Take a close look at the SCSI vs. IDE models of hard drives from the different manufacturers. Compare the geometry of the SCSI version of a model with the IDE version of the same model and you will see that the only thing different is the electronics card attached to the drive. All the mechanical internals of the drive are the SAME. The mechanical parts (wether SCSI or IDE) are put through the same QA test, etc before being given the electronics board.
    I agree that SCSI is better for server/data warehousing applications due to all the reasons you mentioned. If you're just looking for some way to store all you MP3s cheaply or running an in-home server, then IDE works just fine.
  • Try asking a Sun rep why a 18GB drive that can be ordered at CDW for $500 and the 'Sun OEM'd' model costs $1300. They'll say "We only select the
    best quality drives and test them further to make sure they are stronger, faster and blah blah blah."

    You may or may not agree that that cost difference is worth it, but Sun is telling the truth. I used to work for them, and AFAIK, there is no other OEM that is nearly as tough on drive vendors as Sun.
    Sun *insists* that a representative sample of documented production runs for Sun pass their reliability tests - if they don't, they're rejected. And they've been known to reject entire 18-wheel trucks full of disk drives if the test units aren't up to spec - ouch, that's gotta hurt if you're the drive vendor...
  • Why bother with a shim when you can get an Adaptec UDMA/66 RAID (AAA-UDMA) [adaptec.com] card or a Promise SuperTrak 100 [promise.com] RAID card and handle the storage natively? Both products have been available for a little while and are past version 1 drivers, so they should be fairly stable. Both products will do RAID 5 with 8 or so drives (4 controllers, 2 drives each). At 8 80GB drives in a RAID 5 configuration with one hot-spare, you wind up with 480G of safe storage. Put two cards in a system and you're almost at the terabyte mark. I've used many Promise FastTrak cards in small servers to mirror the data drives, and I've never had one card fail yet. (I did have a drive go bad and the product worked as advertised...) I wouldn't bother with a SCSI solution unless you're going with SCSI drives. As usual, use the right technology for the job.

  • He specifially stated he wanted to attach an IDE drive to his LVD chain.

  • I can think of several reasons. First, SCSI controllers have had RAID for longer, and their support for it is likely better tested and more stable. That's just conjecture, of course, and the gap seems to be closing rapidly, but it's still a concern for the present.

    Second, SCSI uses fewer system resources per drive (1 IRQ per 8 drivesvs. 1 per 2 drives for IDE); on a machine that's limited on IRQs that could be a pretty useful feature. I dunno if the IDE-on-SCSI things also buy you the other nice SCSI features like disconnected operation and reduced CPU usage, but that would be a nice reason to use one of these products as well.

    Last, perhaps the poster in question already HAS a nice SCSI controller and just wants to make use of it, rather than turning on his mobo's built-in IDE controller and losing an IRQ.

    As you say, the right tool only makes a difference for the right job. However, I think you're oversimplifying and ignoring some things.

    -Chris Hedberg
  • Raidweb, another IDE->SCSI RAID:
    www.raidweb.com

    [insert standard IDE disclamer]

  • erm, it's not exactly hard to saturate 100baseT, even with a single drive =)
  • "SCSI is a business, server-targeted technology. It's a stronger, faster, more expandable technology"

    Do you work in marketing? You managed to say abosolutely nothing in those two sentences.

    Try asking a Sun rep why a 18GB drive that can be ordered at CDW for $500 and the 'Sun OEM'd' model costs $1300. They'll say "We only select the best quality drives and test them further to make sure they are stronger, faster and blah blah blah."

    Traditional SCSI hardware is a low-volume business compared to IDE. This, combined with low demand for non-OEM parts and low demand for large-capactity SCSI drives keeps the prices of SCSI equipment high.

  • It seems that almost all of the IDE based RAID products out there use the controllers from Accusys. Here's one of their products:

    8 drive controller [accusys.co.uk]

    Tried the older, 6 driver version, and it worked pretty well, did about 40MB/sec sustained with 6 drives. Very sensitive to termination.
  • Really? I haven't seen any 10K or 15K IDE drives . . .
  • 3Ware [3ware.com] makes a nice SCSI/IDE RAID board that supports Linux w RAID 0,1,10 or 5 with hot spares. We are using it to support a couple of multi-hundred GB RAID5 servers using IDE drives no problem. You do want to make sure you download their very latest driver and firmware though.

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