Data Recovery Engineer Answers Your Questions

[ronbo613]

Ask a data recovery engineer anything on Reddit.

 

[Elixer]

Hmm... the freezer "trick"

datarecoveryengineer 618 points 11 hours ago

I would strongly discourage it. I guarantee that someone will post a reply saying that "it works," but the science doesn't back it up for modern hard drives.

On older drives (think up to the 2000s) it was actually a technique. The reasoning was that it would shrink the drive slightly and allow a stuck spindle to "unfreeze" (ironically). Newer drives are far too precise for that.

If you stick a drive in a freezer and it works afterwards, it probably would have worked if you'd left it sitting on your counter. Some drives with minor physical issues will work, say, every 5th time you try them, and they might be more likely to work after a long rest, so there's a correlation =/= causation issue with this myth.

My problem with this technique is that it could cause lasting damage to the drive. If the heads are failed, you're potentially looking at platter damage, and if you're not careful, you might even end up with some crystallized moisture from your freezer

To be pedantic, the DoD developed tool is the ATA SECURE ERASE command, is built into every drive made in about the last decade, and just writes 0 to the entire drive (including sectors in the G-list). The 'overwrite with 1s and 0s multiple times' myth is not only time-wasting overkill for drives with GMR heads (again, past decade), but there's the minuscule chance you had some sensitive data in sectors that were added to the G-list after write, which would be missed by something like DBAN.

Does the SSD TRIM command complicate data recovery in any way? I have heard conflicting answers to that question.

[–]datarecoveryengineer 558 points 9 hours ago

Deleted data is often unrecoverable due to the TRIM command. So yes, it does.

Most unrecoverable: some people hear a grinding, clicking, or whirring noise and continue to let their hard drives run for hours on end. This kills the drive. There's a pic in the album at the top of this thread of one case where the platters were completely translucent.
If your drive makes noise and it has something important on it, shut it off immediately.

It ranges from $600-1900 on average. That's a huge range, but lots of stuff can happen to a hard drive. We try to keep costs down because a happy customer will always talk about your business, especially in this industry. With that said, it's not a cheap service

Most exciting innovations are SSDs. Upcoming technology will allow us to recover SSDs that have been completely overwritten with zeros, or wiped. Also innovations to make virtual machine recovery easier have been developed by our programming team.

Depends on the drive. Power on/off cycles on any drive cause wear, as does the drive running even if idle. That being said, enterprise class drives were meant to be run 24/7 and have incredibly high MTBF and low URE rates, so keeping them on is probably a safer bet then dealing with constantly shutting them off.

Consumer drives, not so much. It's pretty much a crapshoot either way. Also, if you want your drives to last a while, don't buy "green" or "eco" drives. They're cheap, their performance often sucks, and you are better off spending the extra $20 on a better drive.

Just some interesting bits I pulled from that thread.

 

[ronbo613]

Hmm... the freezer "trick"

I saw that. To be truthful, I've tried it about a dozen times and it's worked maybe twice. I think it's because it took the hard drive longer to go from frozen to baked. I did put the drives in a ziploc bag with silca gel to prevent freezer burn.

Most of the questions seem to be from people who are more worried about destroying data on old hard drives than recovering data.

 

[osakaboy]

I posted this question on Reddit but no reply

http://forums.anandtech.com/showthread.php?t=2409581