Data Recovery Myths
By Edson Buriche Coutinho on November 12, 2005
Some are users who are desperate because they’ve lost their data, and others are maintenance technicians who aren’t specialized in data recovery, but all face situations when every attempt to recover their data or their clients’ data failed. Some don’t put up with the fact that they were absent-minded enough to invert the polarity when connecting the HD power cable, others keep looking at the dark screen, thinking at how could that happened: the night before the PC was turned off as usual after having worked all day long without a single crash and, when turned on in the morning, the HD is solemnly ignored during setup, the computer doesn’t boot, and the worst: no backup has been done!
Some nevertheless stick obstinately to the data the client can’t lose in any way and promise to come up with a solution.
These are dramatic situations for sure, and they end up leading the victim first try solutions suggested by friends, others researched on the Internet, and so many others “made up” from thoughts sometimes logical and sometimes for pure “belief”.
And those beliefs spread fast – and a lot. Because some were successful in recovering their data by using one of those beliefs, they became really strong for all situations and in fact are more myths than reality, because in many cases they can eliminate the few chances a good professional could have of successfully recovering data at reasonable price, without having to open the hard drive in clean room, what makes the recovery process very expensive.
So let’s take a look at some of those myths, many of them found on the Internet, and separate what makes some sense from what makes the situation worse, eliminating the “beliefs”.
This may be the oldest of all. When the hard drive stops being detected, some people tap it with a screwdriver or something similar during boot.
We have already seen this “procedure” done with an old hard drive, and it was recognized in one of the attempts. The disk worked for some more hours and then stopped for good.
We have received some disks with marks and dents on the outside, due to dozens of “taps”.
We can’t forget that distance between the read heads and the disk surface got shorter as time went by, and some modern disks (already discontinued – that’s lucky) used to let loose a part of the arm where we find the head parking and held it again when activated. It’s usual to find pieces of those heads spread inside disks whose user or technician used the “tap” solution. Those pieces scratch the disk in such a way that there’s no way to recover its data anymore. That’s why the “hit it” technique makes matters worse: before you could recover your data, but after having used it in disk of that type, the disk becomes totally irrecoverable.
This is what happens: if well applied, the taps can help to loose the read arm that has started to get stuck due to some failure in its circuit. They should be gentle, firm, and one at a time. If it doesn’t work after two attempts, you should stop. No brutality, because if the problem is not with the arm the taps won’t help at all, and if they were too hard they can even damage the disk surface.
Crazy as it may seem, there are some people in forums on the Internet that swear they have “solved” the problem with their hard drives by dropping it on the floor (with carpet) from a table (2.8 feet), and use the drive until today without any problem.
We can’t doubt it, because lucky breaks can happen. Therefore we can’t recommend or support in any way someone who says something so silly. Any hard impact, mainly on a drive that’s already not okay and which problem we don’t know, is playing with fate. Trying to guess what the problem might be, without knowing what the real problem is, seriously jeopardizes any chance of data recovery.
If data stored has no value, then playing and trying non-professional techniques is worth it. But the worse is that some people give this piece of advice in hardware discussion forums. Some hard drives stop working due to the fall. No comments...
The freeze it myth is interesting and makes some sense, but the consequences are a disaster!
During the manufacture of a hard disk drive it’s necessary to calibrate the read/write mechanisms so that the heads get correctly positioned over the disk surface at a determined tolerance, in order to allow the heads read and write on the correct tracks without any kind of error.
Some manufactures, in some models and series, record all those parameters in a ROM memory located in the logic board, or a part is recorded in that ROM and another part in an EPROM or some kind of flash memory that’s inside the drive. This explains why many times the simple replacement of a burned logic board for an identical one using the same firmware version doesn’t make the hard drive come back to life: something is wrong on the inside.
There’s also a kind of surface recording that’s made during the manufacturing process, which is called “servo”, that helps the heads to position correctly. Many times that factory magnetic recording is altered by some reason related to the surface material, and the head starts moving back and forth.
Someone suspected it had some relation with temperature effects and decided to freeze the hard drive in the freezer and then run to connect it back to the PC, and bingo! The drive was recognized and worked again... for some minutes. New freezing session and the drive worked for some more minutes, enough to save some megabytes of information. Then the disk stops working for good.
We’ve read in a forum that when we freeze the hard drive, its interior gets “rearranged” and everything goes back where they belong. This information makes some sense, since the retraction of the material due to the low temperature could have helped the read heads find the tracks again, in some cases. But why the drive stops forever?
Because the disk’s magnetic surface was highly degraded and there comes a time when the “freeze/heat” doesn’t work anymore. The result: the few chances of recovering a good part of data have maybe gone to space. Not to talk about the condensation of the air inside the hard disk (yes, the HD has clean air inside it, a filter to prevent impurities, and a dehumidifier sachet). Read our tutorial Anatomy of a Hard Disk Drive to see this.
One more myth “busted”. Regarding the heat it myth, well... I think there’s no need to comment on this, but there are people who commit and support this crime!
Some people say you can make a clean room at home, in the bathroom, by opening the hot water faucet and filling the bathroom with steam, and at that condition the air would be totally clean and you would be able to open the drive without damaging it.
This myth was very well elaborated, but it can also have unpredictable consequences for the data. Have you noticed that when the sun comes out right after thin rain the air seem to be cleaner? And it is indeed, because raindrops have made the dust in suspension go down to the ground. Hard disk greater enemies are dust and humidity. That’s why they can only be opened in a class 100 clean room (where there can’t be more than one hundred dust particles larger than 0.5 microns in any given cubic foot of air).
And someone thought: I turn on the bathroom heater in maximum for some minutes, then turn it off and wait for the small drops to come down until the air gets “clean”. Then I open the hard disk and touch some parts, poke it, nudge it, or even replace the platters.
Well, although it’s a good Idea, the result is a disaster. Very sophisticated equipments are used in a clean room in order to manipulate hard disk’s parts, under controlled temperature, pressure and humidity. All this because we can’t risk making things worse, we have to save important data. If you don’t know what to do with an open hard drive and don’t have the proper tools to deal with it, be sure something very wrong will happen! But we always give luck a chance - it also works!
There are people who replace the disk’s logic board with an equal one from a hard drive that’s working in order to try to revive a dead one.
This is the most sensible myth. The replacement of the logic board works in some cases where the damage is external and the firmware is all concentrated in the controller. So it’s worth trying, and if you do that carefully there’s chance of saving the data.
However, if the drive is recognized but the read is not successful, avoid the other myths described here and send your hard disk drive to a specialized service, in case your data is really important.
Some data recovery software certainly work when we have a pure logical problem. The problem is to use them when the disk shows some kind of physical problem. In this case, the software automatically sweeps the drive and once more the worse can happen: the last chances of recovery without having to open the disk go down the drain, since some circuits stop working during an automatic recovery of this kind. Therefore you need to know when to use this feature.
Some professionals or even companies announce that they “repair” hard drives. We know that it’s impossible, because such professionals and companies don’t even have a proper place for doing so.
What they do, in fact, is change the logic board and/or run a program that hides the bad sectors, the famous “bad blocks” (read our tutorial on this subject). Then they give you the formatted hard disk and tell you it’s been “fixed”.
There’s the refurbishing industry – or even better, recycling – in countries such as India, China and Russia, but in this case the hard drives come without brand or with some mark or tag that says “refurbished” or remanufactured. We’ve seen hard drives of that kind work for some years and others for some months. Those disks, however, were really rebuilt by using parts from more than one disk, some new and some used, and they are good for use in low-income countries, because they’re much cheaper.
What we want to say is that both refurbished and “fixed” hard disk aren’t reliable. If they’re used, they would never store important data, but just be used to surf the Internet or as station disk without any important data.
Some people have already told us that they’ve read in some place or have heard someone say that it’s possible to recover data from a defective disk simply by finding another one that’s exactly the same and transferring the “platters” (media, without the heads) from one HDA (Hard Drive Assembly) to the other.
This can even work if we take into consideration certain factors such as firmware, hard disk drive series, and others. However, the most likely is that data is lost forever due to many other reasons such as inappropriate environment, inadequate technique and tools, anyway, everything you shouldn’t do for absolute lack of condition and knowledge. But, as we always say, luck is a reality.
Data recovery is a specialty and has its reasons to be, because many people and companies can suffer great losses if they lose their data in an accident with no backup – or when it has failed (the famous Murphy’s Law).
Being a professional in this area demands great investment both in study and in equipment, such as a class 100 clean room. That’s why most of the times the cost to have data recovered is not low.
So, run away from professionals and companies that don’t have proper equipment, because as we said, if you leave a disk in the hands of one of those amateurs, they can put an end to any chance of recovering the data later on – it’s the famous “cheap comes dear”.
For those situations in which you’re not feeling secure for trying to solve problems in a hard drive by yourself, look for a company that’s specialized in that kind of service, otherwise the loss is almost sure.
We haven’t mentioned the cases in which data is stored in RAID stripping arrays. The simple attempt to rebuild the RAID can cause definite data loss. So we recommend you keep your backups updated and avoid improvising when there’s loss of data.
We also remind you that diagnostic and estimated cost in a serious data recovery company are usually free of charge.