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Hard drive positioning issues?

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bryanl said:
What about 18 times (150ms)? In my experience, the 1TB and larger S-brands always have a few sectors needing at least 18 spins to read, yet they're never marked bad, while the W&H brands never have sectors that slow (or the were marked off during manufacture). This is with MHDD, a DOS diagnostic.
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I am assuming S brand is seagate, W is wester digital, and H is hitachi?

so you say that with MHDD you see sectors requiring over 18 retries but not being marked bad with seagate, but not with WD and hitachi? interesting observation, it could be an issue with seagate drives in general or a specific model / firmware having a higher threshhold before they mark a sector as failed, what model was it specifically that you had tested this with?
 
taltamir said:
I am assuming S brand is seagate, W is western digital, and H is hitachi?

so you say that with MHDD you see sectors requiring over 18 retries but not being marked bad with seagate, but not with WD and hitachi? interesting observation, it could be an issue with seagate drives in general or a specific model / firmware having a higher threshhold before they mark a sector as failed, what model was it specifically that you had tested this with?
Click to expand...
What I meant was every &#8805;1TB Samsung (F1 and F4 HD204UI) and Seagate (7200.11, 7200.12, and green) had a few sectors needing between &#8805;150ms and <500ms to read, while the slowest sectors of the WDs (1TB EADS, 2TB EARS Black and Green) and Hitachis (1TB 7K1000.C, both 3EA and 3MA firmware) required <150ms, at worst. Also odd: MHDD never gave the same LBA numbers for those &#8805;150ms sectors. IOW those LBAs varied slightly on each pass. I don't know about the faster sectors since MHDD doesn't list their LBAs.
 
OMG. Guys. You are one bunch of very smart and professional people. Respect! I learned few very important things so far from you.

Thank you
 
bryanl said:
10 years ago, Maxtor introduced a line of video media drives designed to reduce dust-related failures by having a head only on the bottom bottom side of the platter. Unfortunately those drives were unreliable for other reasons.
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For some reason i thought that there is vacuum where the heads and platters move. Is there?
 
AstroGuardian said:
For some reason i thought that there is vacuum where the heads and platters move. Is there?
Click to expand...

It was always my understanding that HDDs (and floppy drives as well) employ the Bernoulli effect to elevate the R/W heads above the spinning disk component. Hence, a vacuum wouldnt work.
 
bryanl said:
10 years ago, Maxtor introduced a line of video media drives designed to reduce dust-related failures by having a head only on the bottom bottom side of the platter. Unfortunately those drives were unreliable for other reasons.
Click to expand...

Chief reason bolded, in red.

Seriously I cannot remember when Maxtor made a reliable disk. Way before Seagate acquired them. At least they left Quantum alone (SCSI) when they purchased them. Maxtor SCSI drives have been quite good. (although we purchase nothing but Fujitsu SAS disks now for mechanicals.)
 
Rubycon said:
Chief reason bolded, in red.

Seriously I cannot remember when Maxtor made a reliable disk. Way before Seagate acquired them. At least they left Quantum alone (SCSI) when they purchased them. Maxtor SCSI drives have been quite good. (although we purchase nothing but Fujitsu SAS disks now for mechanicals.)
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N40P nooooo


hahaha
 
AstroGuardian said:
For some reason i thought that there is vacuum where the heads and platters move. Is there?
Click to expand...
Air is absolutely necessary for proper operation of modern hard drives because their heads literally fly over the platters on cushions of air. Without air, the heads would be firmly pressed against the platters by the springs on their head arms.
 
bryanl said:
Air is absolutely necessary for proper operation of modern hard drives because their heads literally fly over the platters on cushions of air. Without air, the heads would be firmly pressed against the platters by the springs on their head arms.
Click to expand...

Not only is air required a certain pressure is required. This is why hard disks have an altitude rating of < 10,000 MSL. Above this the air pressure may not be sufficient to float the heads properly. Disks were made that could work under lower pressures (albeit at greater cost) but SSDs eliminate such requirements.
 
bryanl said:
Air is absolutely necessary for proper operation of modern hard drives because their heads literally fly over the platters on cushions of air. Without air, the heads would be firmly pressed against the platters by the springs on their head arms.
Click to expand...

Got it. It makes a lot of sense. But wouldn't it be better if they found a technical solution where air is not needed? For example air causes friction and slows down the platters and heads, or it requires more power to move them. Has anything like this been tried? Except for SSDs of course.

Come on, you can do it. You are hell of a smart people here.
 
AstroGuardian said:
Got it. It makes a lot of sense. But wouldn't it be better if they found a technical solution where air is not needed? For example air causes friction and slows down the platters and heads, or it requires more power to move them. Has anything like this been tried? Except for SSDs of course.

Come on, you can do it. You are hell of a smart people here.
Click to expand...

Air friction might mean more power consumed, but that is not a big deal.. modern 3.5 inch drives take 2 watts idle and 5 watts on load.
air is useful there, getting rid of it would not be... also, to maintain a vacuum you need the drive to be airtight and manufactured in a vacuum chamber instead of a clean room, making it more expensive.
 
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AstroGuardian said:
Got it. It makes a lot of sense. But wouldn't it be better if they found a technical solution where air is not needed? For example air causes friction and slows down the platters and heads, or it requires more power to move them. Has anything like this been tried? Except for SSDs of course.
Click to expand...
Actually the first hard drives didn't need air to operate because their heads were held away from the platters mechanically. Unfortunately that required holding them much farther away to prevent head crashes, making the magnetic field weaker and the bit density lower. That's why IBM invented the modern disk drive with flying heads, to let the heads operate much, much closer to the platters and thereby strengthen the magnetic signals, but that also required air and a dust-free environment.
 
I opened an old Western Digital IDE 40Gb drive which i have used for long time. It developed bad sectors few years back so i stopped using it. Now, since it doesn't do any good i opened it up yesterday. Of course the platters were perfectly clean but i didn't notice any scratches or traces of wearing off. I also took out the air filter which is supposed to capture internal debris and it was totally clean as far as good eye can tell. Are those debris supposed to be invisible to naked eye or there aren't any?

I tried turning it on (using an old AT PSU) but it didn't turn on. Guess there is some protection so it doesn't work when opened so you don't lose your skin if you touch the rotating platters. Instead there was a sort of squealing. I tried turning it on with another PSU but the same squealing happened. I unscrew one of the platters and gave it to my baby girl to play with since it was all shiny and reflective. She liked it very much lol 🙂 but lost interest in it soon.
 
AstroGuardian said:
I opened an old Western Digital IDE 40Gb drive which i have used for long time. It developed bad sectors few years back so i stopped using it. Now, since it doesn't do any good i opened it up yesterday. Of course the platters were perfectly clean but i didn't notice any scratches or traces of wearing off. I also took out the air filter which is supposed to capture internal debris and it was totally clean as far as good eye can tell. Are those debris supposed to be invisible to naked eye or there aren't any?

I tried turning it on (using an old AT PSU) but it didn't turn on. Guess there is some protection so it doesn't work when opened so you don't lose your skin if you touch the rotating platters. Instead there was a sort of squealing. I tried turning it on with another PSU but the same squealing happened. I unscrew one of the platters and gave it to my baby girl to play with since it was all shiny and reflective. She liked it very much lol 🙂 but lost interest in it soon.
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The drive should have no problem turning on when open; likely has some kind of circuit damage (could be from ESD, or something)

Also, I wouldn't really recommend giving the platters to children (young at least) the lubricant they use isn't exactly child friendly (especially to little ones who like to put everything in their mouth).
 
bryanl said:
Actually the first hard drives didn't need air to operate because their heads were held away from the platters mechanically. Unfortunately that required holding them much farther away to prevent head crashes, making the magnetic field weaker and the bit density lower. That's why IBM invented the modern disk drive with flying heads, to let the heads operate much, much closer to the platters and thereby strengthen the magnetic signals, but that also required air and a dust-free environment.
Click to expand...

It is very important nowadays that the heads are able to change flying height at will. They use a Piezo electric motor on the HGA (Head-gimbal Assembly) to adjust flying height. The heads will move closer for writing, and further for reading.

approx. flying height is ~10 atoms.
 
I wouldn't worry too much, I don't believe it is flat our toxic, but it probably isn't great to have in your digestive system/blood stream.
 
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