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Data Storage

RAID for Zero-G? 123

Cujo asks: "In all seriousness, I need a RAID that supports at least level 3 and stores > 500 GB, and I need to it work in zero-G (but not in a vacuum), and be able to take a fair bit of vibration and noise when turned off. I don't want to spend huge sums: I'm thinking well less than $50,000. I've looked at Apple's XServe/XRaid products, and they look great (about $10,000), but are they rugged enough and who is their competition? Some people make hardened RAIDs for military use, but I'm unfamiliar with the best candidates in that field (and do I really need mil spec?)."
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RAID for Zero-G?

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  • by Ummagumma ( 137757 ) on Thursday July 03, 2003 @10:23AM (#6358205) Journal
    How do you plan on getting this equipment into a zero-g enviornment? That will problable determine if you need hardened/milspec type equipment. If its going up on the shuttle, with those G forces on it during launch, then yeah, you probably do need 'milspec'. If its going to reside in a plane, that does zero-g free-fall testing, you can probably get away with something less... YMMV.
    • by Cujo ( 19106 ) on Thursday July 03, 2003 @10:43AM (#6358386) Homepage Journal

      Shuttle middeck. It's an environment beningn enough for humans, so not as bad as an ELV ride. The drives would be off and parked during ascent.

      • by mcelrath ( 8027 ) on Thursday July 03, 2003 @10:51AM (#6358458) Homepage
        With the drives off and parked I'd think that any drive would work. Zero g shouldn't be a problem since any drive I've seen can work upside-down or on its side.

        The shock tolerances for the drive should be available on the technical data sheets, and I'm guessing that for off-and-parked it's in the 100's of g's or more. You probably want to consider building a custom RAID mount for it with lots of rubber grommets. I know here at WI some of our rocket guys have vibration mounts whose sole purpose is to shake the shit out of electronics and make sure it survives. Glue in and zip-tie all the connectors. All in all, it shouldn't require an engineering miracle to survive launch...

        And hey, what's your experiment? :)

        -- Bob

      • Shuttle middeck.

        You know, with as rediculously expensive as it is per kilogram to launch stuff, you might want to rig a custom enclosure that uses laptop hard drives or microdrives (those little 1GB postage-stamp things). They have IDE interfaces, so I'm sure one rigging the controllers wouldn't be too hard, and you could use software RAID from one of those miniature Via-CPU motherboards.

        As far as G-forces go, pack it all in bubblewrap, which would be entertaining for the crew, as well.
        • And you'd do that for > 500GB? That's more than 5,000 microdrives... I don't think that's more efficient than a couple of 200GB drives.
          • And you'd do that for > 500GB? That's more than 5,000 microdrives... I don't think that's more efficient than a couple of 200GB drives.

            Actually, it would be 500 microdrives; regardless, I agree that would be too many.

            Fifteen 80GB laptop drives, however, would be very practical, but they might end up weighing more than seven or so 200GB drives. I guess it all depends on the final numbers (storage to weight ratio).
            • Laptop drives have, according to a drive manufacturer, much higher shock tolerances than "normal" drives - whcih in turn are much better than preceding disks. Simply a matter of the components being lighter, but made of the same materials. Unless the storage-to-weight ratio came out really wrong, I would prefer laptop drives to desktop style.

        • It IS expensive per unit mass, but it's highly nonlinear. once you get manifested on STS, you can have a certaim amount of weight, and it's usually plenty. Volume, dimension, and power dissipation are more important resources here. Small is good (small and cool are better), but not if we have to spend a lot of meny to create a custom solution.

          They actually do pack midddeck locker equipment in foam.

    • by yasth ( 203461 ) on Thursday July 03, 2003 @10:48AM (#6358436) Homepage Journal
      Actually I would say the opposite. Launch forces aren't that much for a drive esp. as it can be off (or at least not spinning), while the "Vomit Comet" would almost certainly force the drive to be on and take Gs.

      I mean the big reason hard drives fail if dropped is that they are hard bodies and if dropped on a hard thing there isn't much room for compresion so you have near instanareous decelleration. a steady pressure like a launch shouldn't be that bad this desktop IDE drive can take 400 Gs when not on. As for 0g operation, well I wouldn't think that to be much of an issue, as all the drives I know of can be opperated in any position.

      My biggest worry would be heat. Modern drives do get hot, and that might cause problems.

      If one were really worried you could hook up notebook drives in an IDE raid config. High RPM SCSI drives are probably out as it is, and honestly I can't think of much one would be doing in a 0g enivronment that would need the performance.
      • by Cujo ( 19106 ) on Thursday July 03, 2003 @10:52AM (#6358463) Homepage Journal

        The heat is a concern, and the lower the power dissipation, the better.

        The RAID performance in orbit doesn't need to be top drawer, but when it returns to Earth, I want it to perform well and not be a hassle to administer or set up, since there's a lot of data to analyze.

        • by spencerogden ( 49254 ) <spencer@spencerogden.com> on Thursday July 03, 2003 @11:07AM (#6358612) Homepage
          It would seem to me that you would want max reliability on the flight, and max performance on earth. Is the few hours it would take to transfer >500GBs bad enough to preclude copying to a higher performance system upon return. (Assuming the most reliable and fatest solutions turn out to be utually exclusive)

          As a side note: If you are sending an experiment up on the shuttle, aren't there resources at NASA you can check with? Surely someone has sent a hard drive into space before. As someone mentioned, The only moving parts would be in the drives, so everything else is probably more robust than the drives, they are the weak link you need to worry about.
          • As someone mentioned, The only moving parts would be in the drives, so everything else is probably more robust than the drives, they are the weak link you need to worry about.

            Are you sure that radiation doesn't negatively influence the drive's controller electronics? NASA is normally using special testing procedures that electronic equipment is suitable to be operated under the high radiation levels which occur during a shuttle flight.

            • Very true, IANARS (Rocket Scientist) so I forgot about radiation. But again, surely specs on this stuff is availible from NASA. Maybe there are specs on how much shielding consumer grade electronics need?
          • Asking NASA (Score:2, Interesting)

            by dpilot ( 134227 )
            Which brings up a few other questions besides technical limits of hard drives in space...

            On airplanes they want electronics shut off during takeoff and landing. I would expect NASA to be no less stringent about 'spurious radiation' during takeoff and reentry, though probably more technical and perhaps more flexible if you shield carefully.

            I also wonder what they think about 'little embedded gyroscopes' (hard drives) on the shuttle. Do they have to know about every one so they can account for it, are they
            • I doubt the little bit of momentum in a few hard drives could be a factor, but fortunatelt angular momentum is a vector quantity, so it would always be possible to orient half of them "upside down" so the net momentum is zero.

              • Mounting drives upside down isn't an option for many purchased RAID arrays. You could likely build something yourself that would meet those needs that allowed you to mount the drives in any fashion.

                Otherwise, I think the Xserve RAID is a pretty good idea. You could get away with the $7500 model, which supports 1TB RAID 3/5, 540GB in RAID 0. You might get the $11000 model and use RAID 30 or 50 for maximum speed/reliability.

                Also, are there any considerations around the interface?
            • I actually remember reading about this very discussion back when the space shuttle was still being designed. One of the issues was apparently the difference between tapes (which they were using) and hard drives because tapes had a "built in" equalization of this effect and hard drives didn't.

              I doubt it's an issue any more, I jsut remember it so well because I thought at the time it was interesting. I thought I might find an article mentioning it, but no luck. I did, howewver, find this little bit...

              IBM an

            • Don't believe what you read in the "Space Shuttle Operator's Manual". It's not even an official publication. If you want to _really_ understand the Shuttle, read the Shuttle Crew Operations Manual (SFOC FL-0884). It isn't actually a published document...so it may be hard to find, but believe me, it's an excellent read. No "potential customer" who knew what they were doing would read the "Space Shuttle Operator's Manual".

              Hard drives have flown on the Shuttles and the ISS many times before, there's nothi
          • Level 5 RAID has both high performance and high reliability (striping with distributed parity), at the expense of less capacity. I don't think you can do it in software, though, so you need a hardware RAID controller (prob. not a big expense). One thing I like about the Apple controller is that it's dual redundant.

            I'm not working directly with NASA (don't ask. NO - don't.), but I don't believe anyone's flown a RAID before. Alternatives ARE being considered, but I speculate that /. folks have more RAID

            • Level 5 RAID has both high performance and high reliability (striping with distributed parity), at the expense of less capacity.

              You need to reread your books. RAID 5 has basic reliability (can afford to lose a single drive), excellent read performance, dismal write performance and offers the highest usable/raw capacity rate of any RAID type (where the R is meaningful).

            • according to the Software-RAID howto [tldp.org] RAID 5 in software is just peachy.
            • The problem with RAID5 is that the performance when degraded (due to a lost drive) is usually far worse than when the array is healthy. If you design your experiment to use the peak performance of your array then a failure will cause it to fail even though you won't lose any of the data you've gathered so far.
        • The heat is a concern, and the lower the power dissipation, the better.

          I was suprised how cool, quiet, and low-vibration the 10KRPM SCSI drives I have run (latest Seagate and a fairly new Fujitsu). Perhaps simply researching among the newest models of drives will give you adequate power consumption/heat generation.

          The right enclosure is pretty important, too. For example, one nice thing about the high-end Sun workstations (Ultra 60, Blade 2000) is that the disks are mounted with generous space between
        • Convection doesn't work in free fall conditions, so you will want radiative or fan-powered cooling.
        • Remember that in zero G, there will be problems convective cooling, so you WILL need a fan(s) to keep them cool.
  • Have you tried IBM? (Score:5, Informative)

    by Zocalo ( 252965 ) on Thursday July 03, 2003 @10:26AM (#6358233) Homepage
    They do use ThinkPads on the shuttle/ISS after all, so they must have the drives capable of this kind of thing. RAID cabinets and controllers have no moving parts (or maybe a fan or two), so I doubt they would be affected by zero G anyway.

    • Except for all those spinny disk things and those little arms with the read heads on them.

      So apart for that they have no moving parts. :-)

    • by jafuser ( 112236 ) on Thursday July 03, 2003 @11:10AM (#6358642)
      This is actually a good point.

      An array of the model of hard drives normally used in a laptop would probably be ideal since it is most likely designed to:

      • withstand greater accelerations (laptops get banged around a lot more than desktops/servers)
      • use less power (since laptops run on batteries)
      • have a smaller size
      • create less heat
      I'd suggest doing some research to gather the model number of hard drives used in some of the high-end laptops and then go from there.
    • Following up on my own post as something was nagging me and it finally clicked: fans. I think that you are *definately* going to need some fans to provide active cooling on the drives for zero G. I'm not sure, but I doubt that waste heat is going to "rise" in zero G as there is no up or down, so it's probably just going to sit there, slowly cooking your drives. I suspect you just need to push air across the top of each of the drives in whatever configuration you have them mounted.
  • Uh oh! (Score:5, Funny)

    by icemax ( 565022 ) <matthew_d_stone&hotmail,com> on Thursday July 03, 2003 @10:27AM (#6358254) Homepage
    Hey just because NASA has a tight budget doesn't mean you guys can use Slashdot for your R&D!!!
  • Thermal managment (Score:4, Interesting)

    by lonely ( 32990 ) on Thursday July 03, 2003 @10:35AM (#6358323)

    Remember that a lot of mac kit is specifically designed to use convection to move air and therefore heat through the box. For example an old-style iMac will probably melt as it relies heat rising. Not something that is gonna happen in zero-g. You might need to be changing the fans and such like.
    • Well, if they're designed to be rack-mounted (they are), then they have to push iar out the back, since there's no place to go up if you're once of several units in a rack. The Apple RAIDs have two digitally controlled fans.

  • by jpsst34 ( 582349 ) on Thursday July 03, 2003 @10:50AM (#6358448) Journal
    China has announced it intends to accelerate its Mars program, using experience and expertise from its fledgling lunar program.

    They didn't mention China's use of highly reputable sources of expertise, such as Ask Slashdot!
  • Heat and Radiation (Score:5, Informative)

    by ka9dgx ( 72702 ) * on Thursday July 03, 2003 @10:57AM (#6358518) Homepage Journal
    I see three main challenges in this scenario:

    • Heat
      Convection cooling gets assumed into almost everything, so you'll have to make sure the gear gets some air forced over everything to keep it cool. Inside the hard drives, you've got those nice platters pushing the air for you, so that should be ok.
    • Air pressure
      You indicate that there will be air, but not the pressure. You should test your system at the operating atmosphere and pressure for an extended amount of time. This is critical because the hard drives typically float on a cushion of the ambient atmosphere.
    • Radiation
      Since you're outside the 50 or so miles of air which filters out most of the radation common in space, make sure you have hardware ECC RAM, etc. It would also be good to make sure there is a hardware watchdog in place to protect the OS from hanging do to an induced CPU error.
    Testing tip:
    I'd suggest you test the unit, then run the same test with the unit operating upside down, and on each of it's other 4 faces, as a minimum.

    You've got an interesting project, good luck!


  • by Anonymous Coward
    Please, for the love of God and all that is good, do not use an Apple product. We'll never hear the end of it.
    • You can fit the hole half-a-terabyte (500 GB) in a single build to order G5. Plus they use SATA drives so they'll be fast, add that with the blazingly fast G5 DVD Backup and quiet 9 fan variable independent cooling in an aluminum enclosure running a rock solid UNIX based OS with an easy to use interface and you've got a winner!

      To bad Beleaugerd Apple is dying. (tee hee)
  • Solid state (Score:2, Interesting)

    by sigxcpu ( 456479 )
    compact flash memory is not very expansive (~200$ for 1GB retail)
    it is pin to pin compatible with IDE so you can build a standard linux raid
    if you buy bulk I think it will be in your price range
    • Compact flash is really really slow. That may or may not be a problem.
    • Is compact flash self correcting? I would have though that the incidental radiation would not be too nice.

      Otoh, non-rotating disk memory is fast and only uses a disk during startup and shutdown (whether failure or otherwise). Normally such solid state disks have ECC and so on and they are much faster than conventional disks. You can also RAID them for additional reliability.

  • by Asprin ( 545477 ) <(gsarnold) (at) (yahoo.com)> on Thursday July 03, 2003 @11:02AM (#6358567) Homepage Journal

    Boy, those budget cuts at NASA must be getting bad if they're coming to us for advice!

    /ducks, covers and runs!
  • by isaac ( 2852 ) on Thursday July 03, 2003 @11:15AM (#6358697)
    For anything operating on the shuttle, you're gonna have to consider heat dissipation (convection cooling won't work!), outgassing properties (closed environment), vibration and mounting (not so much how the drives are affected, but how the drives affect everything around them), and gyroscopic forces, (There may be real issues with mounting a rack of 10k drives with all spindles on the same axis), size, weight, and power consumption, just for a start. You really need to provide a more complete spec to get recommendation,

    What's your experiment budget? If you have the option of going solid-state (i.e. flash), that may simplify things - you mentioned write performance was not critical. You clearly want to use the largest, slowest (rotationally) disks possible to minimize space and power consumption. Perhaps a hardware ATA or SATA raid controller in a chassis with e.g. 8 180-250gig drives in a 0+1 configuration?


  • by joehoya ( 541611 ) on Thursday July 03, 2003 @11:37AM (#6358899)
    I have worked with these guys [mt-optech.com] before and they are a great group. They have a lot of experience building rugged mass-storage solutions for airborne and military applications. In addition, they are a relatively small company, with a lot of engineering capability, so they should be able to give you personal attention and help you work through the various issues involved in this type of system.
  • by 4of12 ( 97621 ) on Thursday July 03, 2003 @11:39AM (#6358914) Homepage Journal

    I've heard it costs about US$10K per pound to put an object into orbit.

    If that's true, why isn't weight more of a consideration?

    I presume your project's individual cost limit is preventing you from investigating solid state disk solutions, which would probably be less susceptible to shock than platters in a magnetic disk hard drive.

    • $10,000 per pound is an average cost, not an incremental cost. You get that figure by taking the average cost of a launch and dividing it by the average payload. Adding another pound of payload does not make the shuttle cost an extra $10,000 to launch. Up to a point, they have to put in a little more fuel, which is cheap. Once you pass the shuttle's capacity, then you simply can't add more weight at all no matter how much money you have. The drive to bring in the total weight under capacity is the reason ev
  • Paul, hello, I've just sent an e-mail from my work address. I've got some contacts for you in the Balitimore area. If you would like a sales rep to call, please reply with your contact information via e-mail and I'll pass the info right along, and pass you some names / numbers / e-mail addresses as well.
  • IIRC, Harddrives are already vacuum sealed.. so it shouldn't matter if the surroundings have gravity or not.

    The vibration is more of an issue; however, if the drives are parked.. it shouldn't matter too much.. I mean, they *do* go through UPS and the USPS often enough without too much damage.
    • The vibration is more of an issue; however, if the drives are parked.. it shouldn't matter too much..

      Maybe not to the drives but the whole system must be considered. Drives don't work well when the power or data cables shake off or the raid board or CPU on the system comes loose. Machines exist to shake 'n' bake equipment (NASA or its contractors will have them). I wouldn't send up an experiment unless it passes a ground simulation of the vibration, G-loads, temperature, etc. that it will experience on l

    • IIRC, Harddrives are already vacuum sealed.. so it shouldn't matter if the surroundings have gravity or not.

      What does vacuum sealing have to do with whether or not zero-gravity will cause problems for the drives?

    • I don't think hard drives are vacuum sealed. Most of the hard drives I have taken apart have an airhole. I have been told it is for pressure equalization. Some of the old IBM Deskstars have a warning to not cover the hole. So at the very least I would not assume that a hard drive is sealed.
    • I'm not sure if you mean they have a vacuum in them, or if you mean they are airtight...

      They cannot have a vacuum in them, as the head gap is created by the bernoulli effect, and without it, the drive would quickly destroy itself!

    • Hard drive are totally not vaccum sealed. Most even have breathers. They're dust sealed (which is why there's that little snake looking thing leading from the breathing hole to the internals)

      Hard drive may have had a vaccum back in your day but today that's utter crap.
  • by linuxwrangler ( 582055 ) on Thursday July 03, 2003 @11:59AM (#6359111)
    You are sending up an experiment on shuttle mid-deck which I would hope implies that the experiment is worth the significant risk to human life and great expense that this requires.

    But no, you are looking to cheap-out on the drives that are undoubtedly critical to the success of the experiment. That's pretty damn penny wise and pound foolish.

    Having vented...

    I suspect that NASA has specs and requirements for experiments on spacecraft if not for protecting the integrity of the experiments then at least to protect the astronauts and shuttle. What do those specs dictate?

    If you can use COTS hardware then I suspect that laptop drives are your best bet for not only ruggedness but also weight, power draw, and size.
  • I want to know where you're getting Zero-G from!!!

  • You are asking for a zero G drive system. Zero G is no gravitational forces... so what is the problem?

    If a drive can be mounted in ANY direction, it can take 1 G in any direction, and certainly zero Gs which is easier than the 1Gs most drives experience. If youre asking for zero Gs, youre launching the drives into space arent you? If so, shouldnt you be worried about the Gs during takeoff??? So shouldnt you be asking about say 100Gs while off, instead of 0 Gs which ANY working drive in the world can ta
  • Have you looked at a solid state solution. Not really cost effective, but you can certainly guarantee that any launch/re-entry gee's will be catered for.
  • You'll need SCSI (Score:3, Informative)

    by MrResistor ( 120588 ) <peterahoff.gmail@com> on Thursday July 03, 2003 @12:29PM (#6359386) Homepage
    If you want RAID-3 you pretty much have to go SCSI. There may be a way to do it with ATA drives, but I haven't heard of it.

    The other reason you want SCSI is reliability. That's one of the reasons SCSI drives are so much more expensive. I've seen more than one SCSI drive get dropped on a hard tile floor and still be usable for a year or more (These are half hieght Seagate and IBM, 7200 or 10k RPM, YMMV).

    If you do decide to go IDE, try to use laptop drives. They have MUCH better g-force tolerance than the standard 3.5 inch IDE drives. However, I've still never seen one survive getting dropped on a hard tile floor. Shock and vibration are different things, though, so the laptop drives still may be a better choice. You can

    You could go flash, and that would take care of the vibration/shock issue, but at 1GB each that's an assload of IDE controllers you have to somehow get working together. Assuming 4 per controller, that's still 125 controllers. Even if you solved the IRQ problem, where would you put all of them? Space is a precious comodity on these missions. Plus at $200 each that means $100k for 500GB, which seems to be out of your budget range. A custom motherboard with 125 PCI slots is certainly out of your budget range.

    What I would do is talk to standard RAID vendors like EMC^2 or Ciprico and see what they've got. I know a company that would be happy to design and build a shock-mount for a standard raid chassis for you for probably under $10k. You could also go somewhere like Musicians friend and buy a road case, which will certainly have some anti-shock measures, for a few hundred dollars if your needs won't be too severe.

    I very much doubt that zero-g will be an issue at all. The things that will be problems have already been mentioned by other posts.

    • If you want RAID-3 you pretty much have to go SCSI. There may be a way to do it with ATA drives, but I haven't heard of it.

      You haven't looked very hard.

      In any case, he said "at least RAID3" which implies that he is fine with RAID5 also.

      What I would do is talk to standard RAID vendors like EMC^2 or Ciprico

      What, so he can pay 10X as much for the same thing? A 500GB RAID is as few as two hard disks these days.

      • You haven't looked very hard.

        You're right, I haven't, because if I have data that's important enough or big enough to require any sort of RAID I'm going to also want the increased reliability of SCSI drives. If he's even thinking of using anything beyond RAID-0, this is obviously a consideration for him.

        What, so he can pay 10X as much for the same thing?

        No, so he can get the same thing for less than it would cost him to engineer and test a custom solution for the problem he describes. My company resel
        • My company resells EMC^2 and Ciproco RAIDs

          Wow, big surprise there.

          As you pointed out, he wants "at least RAID3", which will NEVER be satisfied with only 2 drives.

          I said as a minimum, not "as a minimum that would fulfill his requirements".

          I think you legacy SCSI RAID guys are scared. Your market is shrinking, and the future is bleak. I've set up over 8TB of ATA based RAID at work across various systems, and it's really been as reliable as other SCSI and FC RAIDs we have had in the past. We have ne
          • My company resells EMC^2 and Ciproco RAIDs

            Wow, big surprise there.

            But we wouldn't sell one to him, or anyone else, except as part of our Digital Video Server product, which I wouldn't recommend for this purpose even if he did have the budget for one, which he doesn't.

            I said as a minimum, not "as a minimum that would fulfill his requirements".

            If it doesn't pertain to the actual question being asked, why the hell did you bother to post it. I agree with the basic statement (although I'm wondering wher
  • If you don't need random access, tape drives might be more robust. You can still do a RAID of them if you wish.
  • Why is everyone assuming that zero-G implies a space shuttle ? Its terribly unlikely that NASA tech's are onto slashdot- are they ??

    I guess he needs it for something simpler - such as skydiving- or anything that involves free falling - maybe a laboratory experiment - something to do with air/fluid flow perhaps ?

    be that as it may, I concur that standard IDE's should do for 0g, but of course - u need to investigate u r requirements better.
    • I guess he needs it for something simpler - such as skydiving

      I know that whenever I skydive, I strap on my parachute, a reserve, and a 500GB raid pack. Makes the free-fall go just a little bit faster.
    • by xrayspx ( 13127 )
      I wanna see some goofball jump out of a plane with 1/2 TB of NetApp strapped to his back :-). With that kind of weight, they would have to do RAID1 of the skydiver as well.
  • It's not like it's going to put any stress on them :) Fluid or ball bearings should work fine.

    You will have to pay carefull attention to vibration and shock considerations though. Are you going to be accelerating quickly? If so, you will need some kind of packing that can handle a lot of displacement. For vibration, I would personally think it would be easiers to isolate each drive from the chasis using some kind of foam or something, and also cushion the rack. It would require much more work to get the ra
  • Let's see, you have been entrusted with finding RAID storage that is going to be floating around in space, or perhaps mounted in diving or falling airborne devices, and you are unfamiliar (scary in itself) with what's out there, and with this kind of risky work you are reaching out for help from... Slashdot?

    Let me just say, YIKES!
    • Dear slashdot,
      I have been having these pains deep in my brain. What sort of treatment and medication can you help?

      I am sure the slashdot crew are the only people that could make the solution involve Linux and 50 open source applications.

      • Re:Scary (Score:1, Informative)

        by Anonymous Coward
        Dear slashdot, I have been having these pains deep in my brain. What sort of treatment and medication can you help?

        Dear Leroy,

        I'm sorry, but the pain will keep getting worse until the hatching. Don't worry - you still have a few months to live, as it avoids eating the vital parts of the brain until near the very end.

        May I suggest making the most of it, and traveling to nations you don't like, in the hopes that the hatchling stays away from people you care about?

        - Mad Scientist # 28

    • Re:Scary (Score:4, Interesting)

      by Anonymous Cowdog ( 154277 ) on Thursday July 03, 2003 @02:24PM (#6360787) Journal
      Some issues I haven't seen mentioned:

      1) In zero-g, will lubricants (minimal as they are) be more prone to leak out?

      2) In zero-g, will friction be slightly lower, and will this cause any problems? Does modulation of RPMs depend in any way on any component of friction that is influenced by gravity? How about head movement?

      3) Is head movement and position affected by gravity? I'm guessing not, but then, I'm just joe random slashdotter.

      4) Will vibration issues be introduced by the removal of the (possibly dampening) force of gravity? Note I am not talking about external vibrations here, I'm talking about vibrations of the hard drive itself.
      • 1) nope
        2) nope. Drives have stepping motors, which keep a constant speed or deal with it if they can't.
        3) somewhat, but not really. If you were really crazy you could reformat all the drives when you get to zero-g to assure absolute alignment but this is not necessary with newer, more expensive drives.
        4) no. Gravity is a constant force therefore has no damping effects.

        hehe didnt' meant to shoot you down but that's what came to mind.

  • by Anonymous Coward
    ok..not the shuttle but a rocket (far more hostile than the shuttle i'd imagine). experiment worked for 3 days, data returned safely. equipment :
    2 x 533Mhz Alpha 21264As (164LX boards) with 1Gb RAM (ECC) each, RAID-5 using ICP-Vortex boards with 128MB ECC cache RAM each and 7 x Maxtor 120GB HDDs with hot swap PSUs. systems mirrored each other, so there was 400GB of usable space (roughly, 2 hot space + 1 checksum drive). total cost was around $10K including custom parts (boxes, power distribution, batteries,
  • You don't mention storage capacity needs. You do mention in a message that low power drain is a good thing. And since this is going into space, I'm sure that any weight savings are a good thing.

    How about a RAID of IBM/Hitachi Microdrives? [hgst.com] They're IDE compatible with the right cabling, use less power than any other rotating storage, and are super shockproof. Of course, given their size, they weigh very little relative to other rotating solutions.

    The only problem I can see is that they're only good for 1G

  • yea ... go with one of those xserves. that'll be like $10k. then, pay me the other $40k and i'll hold it for you
  • The Xraid would likely be tought enough, but sadly, the Xserve itself my not be able to handle launch. It's so thin, that many users have bent the tope covers, or had the entire unit warp on them.

    Cooling the units shouldn't be an issue, the fans are powerful enough that in null gravity they'd be able to propel the unit:)

    And, i know that at least one company was planning on using G4's in space, so there should be some studies on radiation effects and such on those processors floating around somewhere....
  • I'm absolutely amazed no one has mentioned StorageReview [storagereview.com] yet. They have an extensive listing of new and old drives (SCSI/PATA/SATA), they measure the heat output of each drive in their review and compare it to similar drives.

    Their List of Drives by Heat Output [storagereview.com] shows the Maxtor DiamondMax 16 (160 GB ATA-133) to be the coolest at 13 degrees Celcius and the next coolest/largest coming in at 200Gb and 19.2 degrees C. I highly reccommend going in and doing a head to head comparison because they break the temp re

  • Years ago when I had some experience with shuttle operation there was always the issue of testing and certifying equipment as being safe. For example, that plastics don't outgass volitile compounds, things won't catch on fire, etc. Such certification can be expensive and involve a ton of paperwork. Say a $5 object requires $10,000 worth of assurance.

    So unless you want to pay for this process, find equipment that has already been certified. Sorry but I can't help you here, but NASA probably can.
  • Suggestions (Score:1, Troll)

    by drsmithy ( 35869 )
    The best setup for this would be a RAID 10 or a number of RAID 1s (all with three or four disk mirrors). Avoid RAID 5 - it's write performance is (comparitively) dismal (I'm assuming you'd be writing a lot of data) and it's more vulnerable to disk failure.

    Apple's RAID is probably the best off-the-shelf product. Or if you want to DIY try:

    seven or eight three-disk 80G RAID 1s using laptop drives, or

    three or four three-disk 160G RAID 1s using SCSI drives.

    Stripe them if the space has to be contiguous (ie

    • Good stuff, thanks. Don't know why someone modded that "troll."

      We don't want to DIY, but we may have a packaging problem with standard rack-mounted components. For some obscure reason (or possibly no reason at all [auckland.ac.nz]), the midddeck lockers are just a hair too small to accomodate rack-mount equipment. So, ideally I'd have an internally redundant RAID controller that I could repackage easily.

    • You'd also want to consider things like radiation hardening for the case. I'm sure the people at NASA could help you with that.

      not really an issue. The shuttle flies at 400 km altitude, which is not a bad radiation environment, and the RAID would be inside a midddeck locker, which enjoys a fair bit of protection form radiation. That an the usual aluminum cases provide plenty of protection. Also, we'll be near solar minimum when we launch.

  • You might mount every other drive upside down as to cancel out the torque from spinning up/down. That would eliminate some stress on the disks, and then you can allow the drives to float more freely, reducing the shock from thruster action.
  • I built a project that flew on the VomitComet 20+ times in the early 90's. One of the main goals of the project was to use off-the-shelf equipment. At the time I used a Connor hard drive. Powered it up after take-off, and power-down on landing. I accumulated nearly 2 hours 0G running the system with no problems at all. With today's drive technologies, you should have no problems. We just made sure that we used a lot of vibration absorbing material. Syntroxis ps: ball mice won't work in 0G, a trackball
  • Do you absolutely need the data to be randomly accessed on board? Cos you might just take a DVD writer and a lot of DVD's, Or how a bout a tape drive, and a few tapes to write on? These might serve your purpose just as well - IF you don't need to read stuff on the shuttle, but merely record. Less power, probably less weight as well. Just change the tape every day or so.

  • I'm so glad I have a huge email archive

    See the article here [spaceref.com]. Called "2001: A Space Laptop", they discuss what's involved in using computers in space. It's a little dated, and we can hope they're using better computers as the spec at that time (2000) was a IBM 166MHz Pentium MMX Thinkpad.
  • Hey, I remember in the extremely old day of computers the number of G forces the drive could take was clearly posted on the drive. For example, my old Fujitzu MPU drives had clearly on the label "Do not subject this device to more than 40G's."

    I don't really thing the environment will harm things too much, just make sure you have this thing buckled down really well, and that you have it lead shielded (those little dark plastic bags work for electrostatic dissapation, would work great because the shuttle
  • and I need to it work in zero-G (but not in a vacuum)

    First off, this states that you explicitly need it not to work, i.e. "fail" in a vacuum. I doubt this is your intent. If you need something to fail in a vacuum, one idea may be to have a membrane holding back some sort of acid at air pressure, but which bursts and destroys your media at a sufficiently low pressure. If you merely don't care about failing in a vacuum, then leave that out of all future problem statements.

    Secondly, to all the posters b

I've finally learned what "upward compatible" means. It means we get to keep all our old mistakes. -- Dennie van Tassel