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?)."
I don't have an answer, but... (Score:5, Interesting)
Re:I don't have an answer, but... (Score:5, Informative)
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.
Re:I don't have an answer, but... (Score:5, Insightful)
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
Re:I don't have an answer, but... (Score:3, Funny)
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.
Re:I don't have an answer, but... (Score:1)
Re:I don't have an answer, but... (Score:2)
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).
Re:I don't have an answer, but... (Score:3, Informative)
Re:I don't have an answer, but... (Score:2)
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.
Re:I don't have an answer, but... (Score:4, Interesting)
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.
Heat and Perfformance (Score:4, Interesting)
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.
Re:Heat and Perfformance (Score:5, Insightful)
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.
Re:Heat and Perfformance (Score:1)
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.
Re:Heat and Perfformance (Score:1)
Asking NASA (Score:2, Interesting)
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
Re:Asking NASA (Score:2)
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.
Re:Asking NASA (Score:2)
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?
Gyros (not the sandwich) (Score:2)
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
Re:Asking NASA (Score:1)
Hard drives have flown on the Shuttles and the ISS many times before, there's nothi
Re:Heat and Performance (Score:2)
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
Re:Heat and Performance (Score:2)
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).
Re:Heat and Performance (Score:2)
Re:Heat and Performance (Score:2)
Re:Heat and Performance (Score:2)
For writing, we don't need anywhere near peak performance. We estimate peak rates of 4.5 mB/sec, and average more around 0.5 mB/sec.
Re:Heat and Performance (Score:2)
The chokepoint is the downlink, and the SHUTTLE deosn't really use DSN per se. Anyway, DSN generally tapes all the data they get (without unpacking it), but passes it along ASAP to its destination. There the responsibility for efficient archiving and retrieval lies.
Re:Heat and Perfformance (Score:2)
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
Re:Heat and Perfformance (Score:2)
Re:Heat and Perfformance (Score:1)
Have you tried IBM? (Score:5, Informative)
Re:Have you tried IBM? (Score:1)
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.
Re:Have you tried IBM? (Score:2)
Re:Have you tried IBM? (Score:5, Insightful)
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.Re:Have you tried IBM? (Score:1)
Re:Have you tried IBM? (Score:2)
Uh oh! (Score:5, Funny)
Re:Uh oh! (Score:5, Funny)
Re:Uh oh! (Score:1)
Thermal managment (Score:4, Interesting)
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.
Re:Thermal managment (Score:2)
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.
China plus /. equals Trip to Mars! (Score:4, Funny)
They didn't mention China's use of highly reputable sources of expertise, such as Ask Slashdot!
I'd be proud to help (Score:2)
Heat and Radiation (Score:5, Informative)
- Heat
- Air pressure
- Radiation
Testing tip: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.
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.
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.
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!
--Mike--
On behalf of non-mac users everywhere.... (Score:2, Funny)
Speaking of which... (Score:1)
To bad Beleaugerd Apple is dying. (tee hee)
Solid state (Score:2, Interesting)
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
Re:Solid state (Score:2)
Radiation sensitivity? (Score:2)
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.
Now THAT's a tight budget! (Score:3, Funny)
Boy, those budget cuts at NASA must be getting bad if they're coming to us for advice!
Seriously? There are a lot of factors to consider. (Score:3, Interesting)
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?
-Isaac
You may want to talk to these guys (Score:5, Informative)
Cost Per Pound Issue? (Score:3, Insightful)
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.
Re:Cost Per Pound Issue? (Score:2)
ATTN: Paul, got some contacts (check your e-mail) (Score:2, Informative)
Zero-G likely matters not (Score:2)
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.
Re:Zero-G likely matters not (Score:3, Insightful)
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
Re:Zero-G likely matters not (Score:2)
Re:Zero-G likely matters not (Score:2)
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?
Re:Zero-G likely matters not (Score:3, Informative)
Re:Zero-G likely matters not (Score:2)
Re: (Score:2, Informative)
Re:Zero-G likely matters not (Score:3, Informative)
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!
No they're not (Score:1)
Hard drive may have had a vaccum back in your day but today that's utter crap.
Wait a friggin minute (Score:4, Redundant)
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.
Never Mind RAID. (Score:1)
What did you mean? (Score:2)
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 solid state? (Score:1)
You'll need SCSI (Score:3, Informative)
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.
Re:You'll need SCSI (Score:1)
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.
Re:You'll need SCSI (Score:2)
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
Re:You'll need SCSI (Score:1)
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
Re:You'll need SCSI (Score:2)
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
Do you need random access? (Score:2)
Not Space (Score:1)
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.
Re:Not Space (Score:3, Funny)
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.
Re:Not Space (Score:1)
You're forgetting about terminal velocity, and it's relationship to surface area vs. mass...
--JoeRe:Not Space (Score:2, Funny)
They should all work in 0gave to pay carefull atte (Score:2)
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
Re:They should all work in 0gave to pay carefull a (Score:1)
Re:They should all work in 0gave to pay carefull a (Score:2)
Re:They should all work in 0gave to pay carefull a (Score:1)
Scary (Score:1)
Let me just say, YIKES!
Re:Scary (Score:1)
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)
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)
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.
Re:Scary (Score:1)
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.
been there done that. (Score:1, Informative)
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,
Mod Parent Up! (Score:1)
How about microdrives? (Score:2)
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
solution (Score:2, Funny)
Macs in spaaaaaaaaaace.... (Score:2, Informative)
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....
Your Source for heat info (Score:2)
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
Certification (Score:2)
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)
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
Re:Suggestions (Score:2)
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.
Radiation hardening (Score:2)
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.
Torque? (Score:2)
Hard drives & 0G (Score:1)
Other solution... (Score:2)
Lik to article: Laptops in Space (Score:1)
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.
G-Forces (Score:2)
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
Language precision, assumptions (Score:2)
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