[Beowulf] Disks fail at what acceleration?

Jim Lux James.P.Lux at jpl.nasa.gov
Wed Mar 22 14:10:06 PST 2006

At 01:24 PM 3/22/2006, David Mathog wrote:
>Anybody know how many g's a typical disk can withstand before it fails?

A lot more than 1g...
You can take a (running) disk and move it through a variety of orientations 
without any problem.  That would put a lot more load on the bearings, etc. 
than any sort of linear acceleration.

But, since you want "real numbers"
looks like 63 G shocks over 2msec, operating... 350 G over 1 msec, non-op.

I found a datasheet for a Hitachi microdrive (intended for a personal music 
Shock (half sine wave) 200 G/2ms
Random Vibration (RMS) 0.67 G (5 - 500Hz)
Vibration (swept sine) 1.0 G 0 - Peak
Shock (half sine wave) 2000 G/1ms
Random Vibration (RMS) 3.01 G (5 - 500Hz)
Vibration (swept sine) 5.0 G 0-Peak

And a Maxtor Atlas drive specs
Shock 2ms 63G read, 30G write
Rotation shock 7000 rad/sec^2
Vibe 5-500 Hz, 1.5G
Rot vibe 25 rad/sec^2

>My earthquake bolted rack might stay upright through the big 7.0
>and yet still be very much damaged afterwards due to head crashes
>on the disks.
>David Mathog
>mathog at caltech.edu
>Manager, Sequence Analysis Facility, Biology Division, Caltech
>Beowulf mailing list, Beowulf at beowulf.org
>To change your subscription (digest mode or unsubscribe) visit 

James Lux, P.E.
Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
tel: (818)354-2075
fax: (818)393-6875

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