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Lord Beau

Perpendicular recording technology and security.

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Does anyone know whether perpendicular magnetic recording technology as in the new Seagate 7200.10 means data is more likely to be recovered after one overwrite or less likely? I've ordered one of these and if it's too noisy or too hot, I'll be selling it on ebay so will wipe it first!

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Does anyone know whether perpendicular magnetic recording technology as in the new Seagate 7200.10 means data is more likely to be recovered after one overwrite or less likely? I've ordered one of these and if it's too noisy or too hot, I'll be selling it on ebay so will wipe it first!

a bit off topic:

my first seagate perpendicular disk, the seagate 160 gig momentus, died after 4 weeks.

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Does anyone know whether perpendicular magnetic recording technology as in the new Seagate 7200.10 means data is more likely to be recovered after one overwrite or less likely? I've ordered one of these and if it's too noisy or too hot, I'll be selling it on ebay so will wipe it first!

a bit off topic:

my first seagate perpendicular disk, the seagate 160 gig momentus, died after 4 weeks.

Hmm.

Not exactly encouraging for a disk marketed as "the most reliable".

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This is pure speculation, but I'd think the answer is yes, simply due to the fact that you have a much greater data density. Many of the issues with data recovery have to do with head jitter and accuracy; the head may be slightly off and record data right outside the track in one pass and not in another. So, with the greater density of the perpendicular drives, you get moe data in those outlying areas.

Also, the data penetrates the media much more deeply than with convential drives. Thus, it could be possible that, as the head ages, it can no longer reach as far down into the media. If that's true, than you may be able to recover data that was stored on the drive months or years earlier. Scary.

Remember kids, the only safe way to wipe a drive is with thermite.

Edited by Zark

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You guys are so paranoid.

Retrieving data from a modern HDD drive which was wiped is difficult to the point of being practically impossible. You would need resources on the order of $millions.

No-one is going to go through that to get credit card accounts or see if you were downloading p0rn, etc.

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Retrieving data can be very easy - if files are deleted, they're still present on the disk until the space they were using is overwritten. Likewise, data from a formatted partition can be very easy to recover, unless it was written over with zeros. If a drive is physically damaged, for example by flood, fire, physical impact or crushing, it's usually possible to recover most data using specialised resources in a clean room - this typically costs hundreds of $/£/€.

It's also possible to recover data that has been overwritten, by looking for magnetic traces of the previous states of the areas that represent bits. This can be made more difficult by overwriting several times with random data, but as we're discussing, this method may not be as effective on perpendicular drives, for all we know.

No-one is going to send a drive off to a professional recovery company unless they know the data is worth it - criminal evidence, valuable secrets, years of work that weren't backed up... but likewise, it can be useful to know how to eliminate the above from a drive before you sell/bin/RMA it.

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I wrote, a drive "which was wiped", meaning completely overwritten with data.

The method of retrieving "magnetic traces of the previous states" is what I was referring to.

Considering the number of bits to process in a modern drive, the expensive equipment, expertise, and labor needed, that method is prohibitively difficult.

Worrying about it is silly. :P

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Guest 888
Likewise, data from a formatted partition can be very easy to recover, unless it was written over with zeros. If a drive is physically damaged, for example by flood, fire, physical impact or crushing, it's usually possible to recover most data using specialised resources in a clean room - this typically costs hundreds of $/£/€.

Instead of writing over with zeros it's better to write over with randomly mixed zeros/ones. If there's only zeros added then the remaining magnetic field is just the same character as the original recording was but only with lower absolute level (ok, error correction bits are separate question). This could be relatively easy to recover, theoretically...

About physical damages, it depends... Sometimes head crushing would wipe out the thin magnetic covering from the platter surface completely. Then there's nothing to recover from these sectors.

But if you just want to destroy the very secret information completely, then better open the drive's cover and remove platters and broke them in pieces. Although I do not know what to do with the drives without platters, it's still better than sledge-hammering the whole drive. At least you can save the PCB... or make a toy for children...

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You guys are so paranoid.

Retrieving data from a modern HDD drive which was wiped is difficult to the point of being practically impossible. You would need resources on the order of $millions.

All you need is an electron microsocope, a clean-room area to work in , and patience. Hardly $millions. But, if you want more practical paranoia, consider this: Modern drives will remap marginally-bad sectors on the fly. This is done by the drive's firmware and is completely transparent to any computer program, including file wipe utilities. Your wiped drive could have remapped sectors that were completely untouched by the drive wipe utility. Such sectors are easily recoverable.

This is what finally convinced me that drive wiping is useless and that physical destuction is the only way.

No-one is going to go through that to get credit card accounts or see if you were downloading p0rn, etc.

Just because your life is so boring that you have nothing interesting on your drives doesn't mean we don't. :P

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