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Cause of Hard Disk Failure
Hello All
A question came up on a different NG about whether the constant changing, rearranging, formatting or otherwise manipulating data to and from their hard drive wears out the hard disk surface. Does the pick up on the hard disk actually touch the surface of the disk and if so is there any wearing of the surface as in vinyl records and or audio and videotapes? Generally what is the usual cause of failure was a hard disk? Albert |
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Cause of Hard Disk Failure
On Wed, 13 Jul 2011 05:44:10 -0600, Albert
wrote: Hello All A question came up on a different NG about whether the constant changing, rearranging, formatting or otherwise manipulating data to and from their hard drive wears out the hard disk surface. Does the pick up on the hard disk actually touch the surface of the disk and if so is there any wearing of the surface as in vinyl records and or audio and videotapes? Generally what is the usual cause of failure was a hard disk? Albert I apologize, I just googled it and got a real good explanation. http://en.wikipedia.org/wiki/Hard_disk_failure Albert |
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Cause of Hard Disk Failure
Albert wrote:
On Wed, 13 Jul 2011 05:44:10 -0600, Albert wrote: Hello All A question came up on a different NG about whether the constant changing, rearranging, formatting or otherwise manipulating data to and from their hard drive wears out the hard disk surface. Does the pick up on the hard disk actually touch the surface of the disk and if so is there any wearing of the surface as in vinyl records and or audio and videotapes? Generally what is the usual cause of failure was a hard disk? Albert I apologize, I just googled it and got a real good explanation. http://en.wikipedia.org/wiki/Hard_disk_failure Albert Before Hitachi sold off their (IBM acquired) disk division, they used to have web pages concerning hard drive technology. They provided information (in the "IBM way") that the other disk companies don't provide. That information is now lost, as the web pages in question were guarded with a "norobots" and consequently were not archived by archive.org . One thing they were experimenting with, was "contact" style disk recording. They allowed the clearance to drop to zero, between the head and the platter, while the platter was spinning. They were experimenting with lubricants (presumably dry lubricants) which could extend head life enough to make this possible. In their experiments, the head could "fly" at zero height for one month (30 days), before the head was destroyed. So the lifespan at the point they were publishing the results, wasn't sufficient to introduce the feature. Flying height is getting very close to zero, but is still a finite distance, and the heads still don't touch while the disk idles. One innovation on disks, is variable flying height. Modern high capacity drives, use a different flying height on reads versus writes. The head contains a heater. The heater is activated, whenever they want the head to "swell" and get closer to the media. This allows whatever mechanisms they have for tracking flying height, to perhaps maintain the head assembly at some distance, while dialing in a bit of differential height using thermal expansion properties. I've read references to them being able to monitor flying height. Whether this is just for lab purposes, or whether the drive actively uses that capability, I haven't found any reference material on that. Maybe they could use capacitance between head and platter, to measure such a thing. They didn't state what the tech was to allow doing that, merely that they had the ability to measure what flying height was achieved. Flying height can be implied from rotational velocity, head lift factor (wing lift), head load (downforce via spring loading) and so on. But being able to measure it, allows even closer tolerances to be involved. The Hitachi (hgst.com) web pages provided some insight as to how the stuff works, but without detailing everything. For example, on a Hitachi web page that described the solid lubricant on the surface of the platter, I was able to find a patent application with a much greater level of detail of the chemical composition. Still, I wouldn't have been able to *find* that patent, if I didn't have the name of the chemical compound to search with. This is what you get now, from that web site... If you know of a web page cache other than archive.org, you can see if there is still a copy of this around. http://www.hgst.com/hdd/research/storage/as/index.html "Sorry, but that page does not exist!" HTH, Paul |
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