Hard Drives: Can they be used for offline storage?

[counting_crows]

Hi,

Few head failures. Most have bad sectors / weak sectors.

My suspicion is that the "bad/weak sectors" may be due to bad heads, especially when you said this...:

some with bazillions of weak sectors...

For such new drives, the super-paramagnetic effect ("demagnetization") would not be expected

But some of the drives healed (at least for now). After some read/writes, weak sectors disappeared (i am testing with multiple utilities under pure DOS). How can this be explained?

- hence I was looking for other problems which can cause apparent weak sectors, but without being a problem with the media itself. Unless you find the real cause of some of these drive problems (e.g. change the head stack and see if the problems were due to head degradation of some kind) then everything else is a guess... We need data (no pun intended ) about the real cause of the problem...

I am sorry, I can't be much of an assistance here Vulcan. I am an end user -- not a DR person. Changing the head stack and/or figuring out the real problem with the drive is beyond my capabilities.

Vulcan, thank you for the link. Unfortunately it requires subscription, so i cant get it. If you have it, would you please be kind enough to post?

Oh! Sorry about that - I must be lucky to have access to that link I will try to find a different public link... [Edit: Found one, see below]

Thank you very much. I will go through the link today.

Do you have a long-term humidity recorder, where the disk drives are, just to be sure?

Yes i do. And that is myself. I have allergies and sinusitis. I do have a HEPA air purifier in the house too (no ionization, etc). I don't think they are making those drives more sensitive to moisture and dust than a human with allergies is or none of them would work anywhere.

My storage conditions are better than manufacturer specifications for my drives.

Unfortunately you cannot know that Without a gas chromatograph to check for airborne chemical ions, it is impossible to rule-out something in your environment,

I am sorry, this is not making sense to me. We are not doing head-stack replacements in clean rooms. These are normal drives. And my living conditions are optimal since i am allergic to dust and have an air conditioning unit with multi filters plus and air purifier in my room. You can't expect everyone to run gas chromatographs to figure out if they can use their drives or not. If there was some problems with some chemicals, i would have been effected long before the magnetic media.

I think i found the problem! My drive are sensitive to nicotine! Now, it is metastasizing!

One "common factor" with these disks is your storage environment, but as I said, that's just a guess, and no-one can confirm or deny that, without finding the true cause of the read failures with one of your "problem drives"...

Thank you very much for your input. I heartily agree with your approach (even though it might be beyond my own logic and reasoning). I will keep you updated if i can isolate something or if i can come up with solid data.

You are right. It is all talk now. Scientific approach is always preferable. I wish i could be more help.

[Vulcan]

Hi,

And my living conditions are optimal since i am allergic to dust and have an air conditioning unit with multi filters plus and air purifier in my room. You can't expect everyone to run gas chromatographs to figure out if they can use their drives or not. If there was some problems with some chemicals, i would have been effected long before the magnetic media.

The chemical (a metal ion) which affected the GMR heads in the case I dealt with, would cause problems in very small concentrations - people would not be affected (in this case, they did not know!).

My point is that no-one can rule-out that type of environmental issue here, especially since one unusual factor is the fact that your air passes over so many filters - so it is very clean (i.e. no dust) but what other chemicals are impregnating those filters...? I hope you're keeping the drives in sealed, anti-static bags, with some silica gel (which is how they come from the factory) but is that sealing the problem environment inside the bag? Without some analysis of a "problem" drive, we'll never know....

Anyway, I've done what I can here, with comments and suggestions.

Good luck!

[counting_crows]

Edit: New link for the study into disk drive failure modes http://hebb.mit.edu/people/jfmurray/publications/Hughes2004.pdf

Interesting link... However, that article was done in 2004 with citations from research papers till 2003. Higher density drives were not out long enough to be subjects of long-term analysis.

Failure rates (100%) of all drives, the following apply to non-operating drives:

10.1 % Drive Handling Damage
7.7 % Head or Disk Corrosion
1.3 % Head-Disk Sticktion
0.7 % Foreign Gases or Chemicals

Drives have been subjected to long stress tests and were in TOP health before taken offline. "10.1 % Drive Handling Damage" is eliminated.

I don't have a dead drive. "1.3 % Head-Disk Sticktion" is eliminated.

Foreign Gases or Chemicals: This is a very miniscule failure ratio 7 in 1000... And I don't live in an industrial complex or furniture workshop or a chem lab... I believe these would apply in extreme cases. This is eliminated too.

This leaves me with: "7.7 % Head or Disk Corrosion".

So i have 1/14 probability of failure for a non-operating drive as opposed to an operating one ... Yet HALF of my non-operating drives gone while ALL of the operating drives are working!

Conclusion: Maths / Statistics = BS

Disk magnetic media is designed to retain data against thermal decay for five
years (with 100% margin, i.e., ten-year nominal design data life). Thermal decay
slowly turns stored magnetic bit states into magnetic noise, and is a serious
issue today. The bit size is so small at 60–100GB per-disk that simple Boltzman
kT thermal energy at room temperature slowly disorders bit “0” vs. “1”
magnetization states. It’s a hard physics grounded limitation and a subject of
major technology conferences [Moser 2002]. The thermal decay problem can be
avoided by re-recording the data blocks, or by exchanging data with another
drive.

In disk drive archives, each drive should be periodically powered up in a
MAID system, or mounted in a drive tester. At least once a year, drive data
integrity self tests should be run, including SMART drive internal failure prediction
tests, and all drive data exchanged with another drive to avoid the
thermal decay problem.

I believe... what i am facing is indeed Thermal Decay (apart from few with failed heads). If that is so, would rewriting the drive prolong its life? I mean, is thermal decay preventable? From this quote, with the use of "exchanged" word, i can deduce it is preventable. Do you think this an accurate assumption?

[counting_crows]

I hope you're keeping the drives in sealed, anti-static bags, with some silica gel (which is how they come from the factory) but is that sealing the problem environment inside the bag?

Vulcan, some drives were kept open, and some were inside antistatic boxes. No anti-static bags, no silica gels. But the ones in boxes have been open and closed few times even though they have not been powered on. I cannot isolate the problem to open/box factor. Some open drives damaged, some boxed ones too.

[Vulcan]

Hi,

I don't have time to do more in this thread - perhaps other people have more ideas and time to help you.

Good luck...