hard drive crash probability

i posted something to this effect as a comment on another site but i figure it would be interesting for those of you here who are following the irs scandal.

the claims made by the irs is that the 7 hard drives belonging to those being investigated happened to fail abruptly and irrecoverably, in a short period of time after becoming evidence. they go on to say that it is not an indication of a cover up as the drives were very old, as they were unable to purchase reliable hardware due to budgetary constraints. because they were unable to recover any data from them they were sent off for recycling, and their current state and whereabouts are simply impossible to determine.

logically you would expect some of the 82 hard drives that were recovered to have failed in the interim or during testing, but that wasnt the case. in fact given the 100% failure rate of those directly involved over a period of 6 months you should expect that all of them would have failed over a period of time several times longer.

anyway the actual probability that something like that would happen would be: the average rate of failure of similar drives in similar conditions, raised to the power of 7 (the number of drives that disappeared).

the best estimate i could find on the failure rate of drives such as these was about 30% per year. this number is generous as hard drives generally begin showing signs of failure, bad sectors, corrupted files, crashes, operating system warnings etc. but the missing hard drives all failed in a peculiar way, suddenly and irrecoverably.

anyway, with this data we can calculate the probability as .15^7 which equals 0.00000170859375, in other words it should be the expected outcome 0.000170859375% of the time.

another way to look at it would be in terms of odds, the odds of this happening based on the above would be 1 in 585276.

even if all the drives were doomed to die in a year, which they obviously werent, the chances of all 7 failing spectacularly would still be very low. 100% fail per year, 50% per 6 months, so .5^7 =0.0078125 or .7%. another way to read this would be the odds that the drives were destroyed as incriminating evidence, even with these generous numbers the odds of that being true is: (1/0.0078125) -1 to 1, or 127 to 1.

again, the actual probabilities are likely to be much much greater than that, more likely in the millions or billions to 1. to accurately estimate it you would need much better data than what the hard drive manufacturers or large enterprise companies provide. they generally only keep their drives in use for a few years, when higher density drives are available. microsoft or apple's error reports would probably be the closest approximation to these drives that were allegedly very old and poorly maintained. you could then break down the rates of all possible modes of failure including irrecoverable failure without warning, and get something much closer to reality.

the big takeaway from all that though is that this particular outcome is virtually impossible. therefore its just as surely true that the irs did in fact destroy key evidence.

I'm going to have to put on my waders. The b.s. is getting very deep. "Budgetary constraints?" Bwahahaha! I guess they just didn't steal enough to keep the records.

I've had two hard drives fail in 16 years.

I'm going to say exactly what I said a while back in some computer forums in a discussion about it:

I don't believe it is possible at this current date and time. I was even able to revive and get some files off of a 12+ year old dead IDE drive from a computer I used to have when I was in early high school. I was able to revive it for at least a little while. I remember when 60GB was a ton of storage to me...

This being something as big and important as the IRS, then I'd be amazed and infuriated if they DIDN'T have backups of all their information including internal emails. Not to mention what the NSA might have...

Yes, complete BS coming from the IRS on this IMO.

I've never lost a hard drive since the internet was a household thing, yup ooookaaaayyyy!

yea in terms of anecdotal evidence, ive never personally encountered an irrecoverable hard drive either. out of my friends, family and coworkers i cant recall a single instance of such an event even being related to me in conversation.

we should probably do a poll.

I still have a Quantum Fireball going strong since '98, now in my mom's PC.

The secret to hdd longevity is to disable power saving/spin down/up cycles. That's what kills them. As long as they're spinning at full speed they're not wearing out.

However, most people have no clue and so their drives die an needlessly early death for meagre savings on the electricity bill.

100% lies... the hard drive failing, even if it did, would not result in any loss of data. First of all, they are most likely setup on a Microsoft Exchange server for email, like most major companies. This means the actual servers holding the mail are not on the individual computer.

Now, let's just assume, the IRS does not use this configuration, and instead they use a Personal Folders configuration within outlook, which WOULD store emails on their computer. Every single work station would be setup with regular backups on a nightly basis at minimum. And even if they had space constraints on a server backup side, they would at minimum choose to backup main system folders such as Documents, Desktop, and App Data... and the personal folders (ost) file would surely be included.

So long story short... They are lying. They try to make it sound technical and valid but it's a giant pile of horse manure.

The maddening thing here isn't the IRS' claim... it's that their claim is being accepted uncontested. It just proves the whole thing is song and dance. Any data recovery, network admin, IT professional could be sent in to investigate the claim and determine the truth.

originally posted by: Chiftel
I've had two hard drives fail in 16 years.

Yep. Hard drive failures happen (obviously) but hard drives are actually quite reliable, considering their mechanical nature and the amount of use/abuse they take. I'm not buying that these things all failed at once

Hard rive failure is completely irrelevant .. these corporate systems
will berunning multiple failover clusters and at least raid 6.. and disaster recovery in place.

hourly backup and full type of regimes.

losing a hard drive is bull.

a reply to: spiritualzombie

i know right! i didnt even bring up the fact that they cancelled their back up service after the emails were requested, while later claiming that they werent even used for the archiving of emails. all these other coincidences are damning to people like us, but they can just as easily weasel out of them by feigning incompetence, or just claim that they simply didnt have enough money to meet their legal obligations regarding the retention of documents, including email.

so while there are many layers of stink, my original post was to examine the likelihood that the hard drive failures on the client pcs, at least those belonging to the principle suspects, was possible.

because if i was leading the investigation, thats what i would focus on as its easy to quantify statistically, that way they cant worm their way out of it.

a reply to: Chiftel

I would say most people don't ever have hard drive failure. They'll buy a new computer long before any hard drive fails.

The only hard drive I've known to fail was the result of someone kicking the computer out of frustration.

Im sure the nsa has all of the irs email and phone calls, might be on of those moments where the nsa comes in handy, not that any one will come forward with the information.

a reply to: snarfbot

Ouch! The math that you performed is making my head hurt!

I've never seen a hard drive crash either and I've been using computers since the late eighties. Computers may die due to the power burning out, but the hard drive was always recoverable.

Hard drives do fail ... usually within the first one-hundred hours of use. If the seven drives in question were within that one-hundred hour period, the IT staff of the IRS would have been able to restore from back-up without a problem (and probably salvage all data produced in the interim).

Lerner obviously used social engineering to opt out of data restoration. Too easy. This will be the final conclusive finding of any investigation.

Pretty damned sad her salary was covered by your tax dollars, no?

a reply to: Chiftel
How do I disable the power saving mode?

originally posted by: rigel4
Hard rive failure is completely irrelevant .. these corporate systems
will berunning multiple failover clusters and at least raid 6.. and disaster recovery in place.

hourly backup and full type of regimes.

losing a hard drive is bull.

True. Plus, I think we all know it's ridiculous to even think the IRS treats information of any kind like it's worthless and expendable. That fact alone should have been a massive tip-off to those who were inclined to buy into their lies.

I have had a lot of hard drives fail.
I buy a lot of Junk!
from Ebay and second hand shops.
And I put them through a VERY hard time.

you would not believe the amount of crashes I get.
and I have to reformat and reinstall the operating system.

a businesses computer is Very easy on the computer.