Protecting Hard Drives From Jackhammers 32
Faramir writes: "I need some help with a jackhammering problem. You see, construction is going on, oh, about 5-10 feet behind the wall of the lab I work in. Essentially right next to my head. And next to this wall I have a number of PCs and a file server with a bunch of nice SCSI drives. And I have no idea how long it is safe to leave them running." (Read more below.)
"I can look at the vibration tolerance specs for the hard drives (my main concern), but translating this into jack hammer vibrations is beyond my ken. Also beyond the manufacturer's tech support, as I suspected. Any clues? Suggestions? Thanks!"
Perhaps the same principles apply to protecting hard drives from loud music, but since heavy-duty laptops aren't much of a solution for holding a rack of SCSI drives, many of the options mentioned there might not apply.
Another problem to consider (Score:1)
VI
El cheapo technique: (Score:2)
Anyway, one of the tricks, aside from the usual foam and stuff, was to get an innertube (from a bicycle or car), fill it only part way with air, and sandwich it between two sheets of plywood (or some similar material).
That will take out a lot of vibration.
Also, put a small mirror on your equipment. Bounce a laser (solid state laser pointers are a couple of bucks down at the drugstore/recordstore these days) off the mirror and across the room. It provides a good indicator of the vibration.
This guy is right, but if you can't move... (Score:2)
Maybe you could temporarily arrange to work and have the equipment on during hours when construction isn't happening.
For a vibration and impact shock wave resistant material to go under the equipment, look for some stuff called Enkasonic. When I last looked into it, it was made by BASF in a facility of theirs somewhere in the western part of North Carolina. Look it up on Google. Good luck.
Re:This guy is right, but if you can't move... (Score:2)
the obvious answer? (Score:2)
Seriously. If the information on those drives are at all important, then you should either move them to the other side of the lab, or out of that room (cooling maybe a factor if they leave the room).
Re:Opposing-Phase Cancellation (Score:1)
Opposing-Phase Cancellation (Score:1)
This requires an audio system able to generate as much power as the jackhammer noise, and speakers which can withstand generating that sound.
If you are able to do this audio engineering job, I'd like to see the explanation for justifying a "Spinal Tap" quality audio system.
Re:This guy is right, but if you can't move... (Score:1)
OK, so rent a small truck, drive it into the server room, and move all the systems into the truck for the duration. I'm sure any contractor with jackhammers can provide an entryway into the server room.
Linux Jackhammer (Score:1)
Closed Cell Foam (Score:2)
One nice thing about the closed-cell foam is that it can be cut, so one pad can handle several pieces of hardware.
One problem with them is that they are effective insulators--this is bad for anything that vents out the bottom.
Finally, and just for the sake of argument, I'd (gently) topple any towers--lay everything horizontally.
Look at these folks (Score:2)
Check out EAR [earsc.com]
They make all kinds of vibration control stuff - good for low amplitude stuff like you are seeing
Remember one important thing, a poorly designed vibration damper can make things MUCH worse! If the resonant frequency of the damper happens to fall near the fundamental frequency of the vibration, you will get amplification, NOT reduction! Worse yet, if those frequencies happen to be near the critical (aka resonant) frequencies of your hard drives. BTW the greater the damping over the longer the bandwidth, the larger the amplification
These [equipment-...bility.com] guys offer a bunch of information on vibration and shock. I took Wayne's course at his old [ttiedu.com] company back when I was doing vibration testing for a living - They were the only guys doing vibration testing courses in the early 80s
Re:Opposing-Phase Cancellation (Score:2)
Those shakers are nothing but BIG stiff air or water cooled speakers - They typically start at around 10 KILOWATS and go up from there. One of the systems I ran was 23 KVA, and the other was a tad over 100 KVA. I had the biggest amps on the block
foam (Score:1)
Suspend and float (Score:2)
1) Suspend a steady platform with bungee cords, ropes, whatever. It's far more important for it to be flexible than stretchy. You probably want to attach a few cords on the bottom to stop swinging - these should be stretchy.
2) Add extra mass to this platform - something like a layer of bricks. This will put the suspension cords under more tension (which allows them to transmit more vibrational energy), but the extra mass of the system should decrease the motion seen.
3) On top of this platform, put the partly inflated inner tube mentioned elsewhere. This platform holds the computers.
This is more complex than a single suspension system, but a single system will still transmit some key harmonic frequencies. But it's unlikely that two independent systems will share harmonics so there should be very little energy transmitted into the disks.
Sand (Score:3)
OT: turntables (Score:1)
No, wait. That fad died out (no pun intended) a decade ago. Nevermind.
Use rubberbands (Score:1)
Re:This guy is right, but if you can't move... (Score:1)
There is one other thing you can do that no one has suggested yet: put everything on a BIG solid mass, like a cube of steel. Why? Mass by itself 'damps' vibration. The equations of vibration point out that the amplitude of vibration can be reduced with straight damping (foam rubber and the like), or with a huge mass.
The reason the mass works is that the vibratory waves need a whole lot of energy to move a very large mass an appreciable distance, and so for any vibrations which don't register on the Richter scale (earthquake measurement system, I'm in California :) the energy in the vibration will only move that big mass a very small distance quite softly. And that small distance isn't critical to your hard drives.
This is the second order linear differential equation which describes most vibration situations. (Most - for one idealized point mass, a single linear spring, and a single linear damper. Seems quite limited, but most vibration can be described in this way quite accurately. I love approximation.)
m * a + c * v + k * x = F(t)
m = mass (the thing which is shaking)
c = damping coefficient (foam rubber)
k = spring constant (relation between the force applied and the distance the spring moves
F(t) = equation describing the action of the force over time
d^2 x
------ = a
d t^2
d x
---- = v
d t
For the same force, the jackhammer crunching away all day long, a larger mass reduces the acceleration. 'm' goes up, 'a' goes down, simple algebra.
See if you can get a big solid chunk of mass to put everything on top of. But be careful to get something which can't shift internally, it will move more than a single block of the same size will. Maybe a big old steel desk. Whatever you find, I would put rubber cushions between your PCs and the big mass, for more insulation.
Good luck, and backup. :)
Louis Wu
"One of life's hardest lessons is that life's lessons are hard to learn."
Re:Closed Cell Foam (Score:1)
Easy (Score:2)
Unless, of course, your real question is this previous Ask Slashdot. [slashdot.org]
cheap 'n cheerful solution (Score:1)
better safe than sorry. (Score:1)
Worry about building first... (Score:2)
Vibration is one of the worst things for hard disc drives, as the moments repeat themselves. Most G specs for drives are for a one-time shock. Disc drive suceptibility also depends greatly upon the orientation of the drive to the shock as well. Drives ae USUALLY (may vary by drive construction...) much less sensitive when the shock in in the same plane as the platters.
If this is a rack-mounted installation, try industrial equipment isolator pads. Little round things that go between the bottom of the rack and the floor. For desktop or similar, see if you can find an old wavepad from underneath a typerwriter (don't worry, son, look in a museum...) or a half-inch pad of Sorbothane (Costly, ouch....)
You're running tape backups, right? (Score:2)
Trolls throughout history:
It depends.. (Score:2)
It depends, of course, on how long it has been since your last backup and weather there is money in your budget for replacement drives. ;)
I mean, if there's a lot of vibration transmitted through the building structure, you are going to have a lot more to wory about than just the drives having a headcrash.
Jackhammers (Score:3)
I wouldn't try to protect the systems in any way -- just keep an eye on their outside cases and be prepared to clean a little more often. I neglected this in an at-home machine several years back while some wallboard was being fixed, and what I found inside after the work was done was a bit alarming. If I'd just dusted the case often with a clean cloth, I could have kept a lot of that dust away from the components.
I hope the construction goes away soon. It's not much fun.
Annie
*NOT* Anti-static (Score:1)
Shock absorbing enclosure... (Score:2)
Well, you could pick up a shock-absorbing rack. They're expensive as hell, but if this jackhammering is going to be going on for a while (hope you have earplugs!) then it may be worth your while.
Here's one url:
http://www.martindaleassoc.com/its/4xpcmenc.htm
You can probably find more thru google or av. Meantime, get those puppies as far away from the vibs as possible. If you can power the drives off , all the better. It may not totally save them, but hard drives can take a lot more shock when stopped than when running.
Antinoise systems!!! (Score:2)
Here's where you can get it: NCTI [nct-active.com]
Unfortunataly they only sell small consumer electronic devices, so I guess you'd have to count
the number of disks you have, buy 1 antinoise headset [nct-active.com] for every disk, put the headsets on the disks, and off you go!!!
Couldn't be more simple than that (and from only $39, its a steal!!!)
Re:better safe than sorry. (Score:1)
Re:better safe than sorry. (OT) (Score:1)
Recap,
helmet -- protects head (i.e. Hockey Helmet)
hard hard -- protects head (i.e Used in Construction)
ear protection -- protects ears (i.e ear plugs or similar item)
Therefore helmet=hardhat which would most likely mean that hardhat or helmet does not equal ear protection.
Back in the day... (Score:1)
I used to mess with holograms. We would suspend the platform on rubber balls (balloons for small objects). You know the same red ones you used to play dodge ball with. They will damp virutally all vibration and support an amazing amount of weight.
Build a plywood platform big enough to hold your rack and to sit off the floor with the equipment on in. Put the balls under the rack platform. Presto change-o and you are done.
You'd be surprised how much weight those cheesy playground balls will take under these circumstances and how well they dampen vibration. We once did a hologram of a lifesize bronze statue which weighed in at just over 1800 lbs. using this technique.