[HN Gopher] Recover HD Using a Magnet
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Recover HD Using a Magnet
Author : lrizzo
Score : 77 points
Date : 2020-01-02 20:00 UTC (2 hours ago)
(HTM) web link (info.iet.unipi.it)
(TXT) w3m dump (info.iet.unipi.it)
| sdfjkl wrote:
| I've fixed this problem a few times (on different drives) by
| giving the drive a not so gentle thwack with a hammer. The trick
| is to hit it on the long side, which tends to dislodge the stuck
| heads/arm. If you hit it on the top or bottom, you're likely to
| break something, and hits on the short side aren't likely to
| achieve anything at all.
| pmiller2 wrote:
| I've used this method after the fridge/freezer method failed.
| It seems less likely to cause data loss than using a magnet to
| move the head as in the article.
| azinman2 wrote:
| How did the data not get destroyed by the magnet?
| aewens wrote:
| Yeah, this technique should really only be used if, and only
| if, you need the drive itself to be fixed and no longer care
| about the contents of the drive (e.g. if it was in a RAID 1 and
| manually cleared afterwards).
| ebg13 wrote:
| There are actually very powerful permanent magnets inside of
| every spinning hard drive already, so clearly there's more to
| destroying data than just having a magnet nearby.
|
| https://www.kjmagnetics.com/blog.asp?p=hard-drive-destructio...
| has a writeup about trying and failing to wipe a drive with
| extremely powerful magnets.
| mirimir wrote:
| It's _changing_ magnetic fields that wipe HDDs. Such as
| powerful electromagnets.
|
| In a clean (enough) room, they could have opened the drive, and
| just poked the actuator arm.
|
| Decades ago, I had a HDD that wouldn't spin up unless I nudged
| the platter with a pencil erasor. Very near the center, of
| course. There was a hole in the case, in just the right place,
| with Al tape over it.
| pontifier wrote:
| Doesn't even have to be a very clean room... I played around
| with an old 1 gig drive years ago. My friends and I opened up
| the case so we could watch the drive doing it's thing. We did
| a fresh os install and watched as it formatted the disk and
| copied files. The head was remarkably strong, and would move
| so fast it looked like it was in 2 places at once while
| copying files. It was fun to stick a screwdriver between the
| 2 ghostly write arms, and have the screwdriver almost knocked
| from your hand, while the drive went on like nothing had
| happened. It ran for weeks before it died.
|
| I've also stuck a 3 1/4" floppy disk to a huge 2"x2"x5"
| neodimium magnet with no ill effects. The drive was able to
| read it fine afterwards with the same md5 hash of the
| contents.
| commandlinefan wrote:
| If you videoed any of that, I'd love to watch it on youtube
| (or somewhere).
| cecja wrote:
| the whole magnet and hard drives thing is a really old hoax.
| with normal household magnets or even strong neodym magnets
| nothing will happen to your data but if you have a really
| strong industrial electro magnet at hand you can wipe a drive
| with it...
|
| here is an old national geographics video on the topic
| https://www.youtube.com/watch?v=U8LWTe5CqQg
| EvanAnderson wrote:
| Here's my anecdote:
|
| In 2006, while sitting at my desk playing a video on the
| Travelstar 40GB PATA drive in my Thinkpad T22, I held a
| single neodymium magnet (harvested from an old hard disk
| drive) about 6 inches from the left side of the unit (where
| the ~disk was located). The video froze, Windows XP blue-
| screened, and the hard disk drive started emitting a ~10Khz
| whine. I jerked my hand away from the PC immediately when the
| whine started
|
| BIOS would no longer detect the disk on that machine, or any
| other I tried it on (on both USB-to-PATA and honest-to-
| goodness motherboard PATA controllers). The drive spun up but
| made a repeated ticking sound (I assume seeking back and
| forth looking for servo tracks).
|
| I sent the drive to Kroll Ontrack (because, stupidly, I had
| billing data that wasn't backed-up on the drive). The report
| I received back indicated that 80% of the drive's sectors
| were unreadable.
|
| As an aside: The data I was looking for was ASCII text and
| Kroll Ontrack was completely unhelpful in just sending me a
| bitstream image of the drive so I could grovel thru looking
| for data I needed. Being plain ASCII, their "file carving"
| tools didn't locate any of the data. (They sent me a
| "preview" of the data they'd located, and while it got lots
| of Microsoft Office-format files, it didn't have any ASCII
| text files). I offered them a 3x multiple of the rate they
| asked for file-level recovery to simply send me the bitstream
| image of the disk that they'd already made. They wouldn't do
| it, and wouldn't even let me pay to talk to somebody who
| understood what I was asking for. I ended up taking a major
| loss on the billing data I destroyed. I'll never recommend
| them to anybody.
|
| I won't ever play with neodymium magnets around spinning rust
| media again either. I also had a major failure of my
| discipline re: backup at that time, too. The cobbler's
| children always go barefoot-- I was being too cavalier with
| my backup strategy (or lack thereof) and not treating my own
| data like I would a Customer's.
| ebg13 wrote:
| > _the hard disk drive started emitting a ~10Khz whine_
|
| This sounds like the head crashed and physically scraped
| the platter.
| egdod wrote:
| Sounds like a coincidence.
| EvanAnderson wrote:
| It does sound that way but, boy, it was eerily timed if
| it was.
| mlyle wrote:
| Magnetic field falls off with inverse cube of distance
| once you're past the approximate size of the magnet. Not
| to mention that the drive itself is in a ferrous
| enclosure that provides a lot of shielding... the
| magnetic field you applied at 6 inches is approximately
| nothing.
| EvanAnderson wrote:
| I will definitely concede that I may have the 6"
| measurement wrong. Heck-- I may have actually put my hand
| right on the PC.
|
| I stack running hard disk drives, all of which have large
| neodymium magnets inside them, in close proximity all the
| time with no ill effects. It makes no sense.
| noonespecial wrote:
| I'd bet on related, but not what you thought. If I had to
| guess, I'd put my money on the magnet pulling some tiny
| metal bits into the control board and shorting it.
|
| But one thing is for sure. OnTrack are dicks. Can
| confirm.
| dukoid wrote:
| Don't use dd -- use ddrescue (reads all "working" sectors before
| retrying broken ones).
| ddtaylor wrote:
| Does this mean it puts less strain on a potentially broken disk
| in an attempt to maximize how much can be rescued before it
| fails?
| askvictor wrote:
| yep; it's quite clever about how it deals with broken sectors
| too; starts jumping over them in increasingly large amounts,
| and goes back later (in multi-pass) to get the missing bits.
| tyingq wrote:
| If you Google for the word "sticktion" or "stiction" you'll find
| other remedies. Like putting it in a ziplock bag and freezing it,
| or (youch) purposefully dropping it.
|
| All approaches to release a head that's stuck to a platter.
| rgj wrote:
| My anecdote:
|
| Around 1993 I had a Commodore Amiga with an A590 external hard
| drive. A big enclosure that could be connected to the expansion
| port on the left of an Amiga 500, containing a very precious 20MB
| hard disk.
|
| One day, it stopped working. I tried everything but I couldn't
| get it to work. A friend offered to take a look at it so I put it
| in my backpack and took the train to my friend. When connected to
| his A500, the drive worked lime a charm.
|
| When I drove back home in the train I wondered what would be the
| matter with my A500 since it apparently made my A590 hard drive
| fail.
|
| However, once I got home and reconnected the drive, it worked. No
| problem whatsoever.
|
| Until two days later. It failed. You know what's going to happen,
| right? Took it to my friend, it worked, took it back and it
| worked for two more days.
|
| Turns out that disconnecting it, putting it in my bag, walking it
| around for a while worked just as well.
|
| Turns out that disconnecting it, dropping it from 5cm / 2 inches
| and reconnecting it, worked just as well.
|
| Which was what I did for the next four years or so. Whenever it
| stopped working, I disconnected it, dropped it and reconnected
| it.
|
| Always loved the look on the face of people who witnessed me
| starting up my Amiga.
| michaelcampbell wrote:
| "sticktion" was an issue with some early Mac drives.
| netsharc wrote:
| Might as well share mine: one day the magic smoke[0] left a lot
| of components on my PC, including the HD with no backups. I saw
| the board was replacable, so that's what I did: bought an
| identical disk on eBay, some torx screwdrivers, transplated the
| good board to the dead disk, and it worked perfectly fine.
|
| [0] http://www.catb.org/jargon/html/M/magic-smoke.html
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