RAID for Zero-G?

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...

[Ummagumma]

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.

Thermal managment

[lonely]

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:I don't have an answer, but...

[yasth]

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.

Heat and Perfformance

[Cujo]

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.

Solid state

[sigxcpu]

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

Seriously? There are a lot of factors to consider.

[isaac]

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?

-Isaac

Asking NASA

[dpilot]

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 just negligible, are they cumulative, or can you mount every other drive in the rack upside-down to cancel out righ-hand-rule effects?

There used to be a "Space Shuttle Operators Manual" for publicity/potential customers. I believe the local library has one, so I should check out the 'electronics restrictions' section.

Re:Scary

[Anonymous Cowdog]

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.