Question Monitoring writing speed Hard Disk during seismic vibration

Oct 22, 2020
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Hello everybody,
I am an Italian researcher of structural engineering and I'm developing a seismic isolation for server rack. I'm programming few experimental tests on a vibration table. My intent its test the seismic isolation device and measure the benefit respect the traditional system of seismic protection of server rack.

Do you know any method to a continues monitoring of writing speed of hard disk? I found a few software to a simple monitoring of hard disk performance, but are influenced of the OS and other issues. What is the best way to avoid this issue?

There is any method to read the information of the shock sensor of the hard disk?

Thank you very much for your attention.
 
Oct 22, 2020
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Likely the manufacturers already have this data.

For instance:
https://www.45drives.com/wiki/images/e/ed/45D_Gen4_ISPEngineeringReport.pdf

If they won't share directly, they might lead you to down the proper path.
Thank you for the answer. Unfortunately, every hard disk producers that I have contacted not respond to this topic. I think it's a trade secret

I need the continuous monitoring of the writing speed for highlight every modification respect to the normal functionality during the seismic test.
 
Oct 22, 2020
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I can show you how to sense the outputs of the shock sensors on the HDD PCB, if you have a particular HDD in mind.

You might like to start with my tutorial (see the circuit diagram):

http://www.hddoracle.com/viewtopic.php?f=100&t=2637

This datasheet may also provide some insight:

http://www.users.on.net/~fzabkar/L7250.pdf
Thank you for the answer. I don't have in mind any particular HDD, could you suggest one?

There is any HDD with whom is possible getting the information of the shock sensor in a software way?

Do you know what measure does the shock sensor? Acceleration (in g) or any other measure?

Thank you very much for your attention.
 
I don't know how to retrieve shock sensor data via software. Sorry.

The outputs of these sensors are expressed in mV/G or pC/G (millivolt or picocoulomb) depending on whether they are voltage or charge type sensors. There are datasheet references in my tutorial.

NAS/enterprise drives usually have 2 or 3 sensors. Two diametrically opposed sensors are used to detect rotational vibration, while a third sensor responds to raw shock events. Regular desktop models usually have just the single sensor. Some laptop drives have a tri-axis accelerometer.

The only drives I would know how to monitor with an oscilloscope would be those which detect rotational vibration. The shock sensors in this case are amplified and buffered by op amps. Those drives with single shock sensors would be more difficult to monitor because the signal disappears inside the motor controller IC.
 
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Could you write a shell script in Linux to write to your drive? You could use the dd command to write blocks of data to the drive while logging the time stamps before and after each block. You could then correlate the time stamps against your programmed shock events.

You could also log the SMART data at the same time. I would monitor the Write Error Rate and Seek Error Rate attributes in particular. Some drives also record a G-Sense Error Rate attribute.
 

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