There are several forms of data degradation and corruption such as during transmission or receiving a digital signal or corruption or degradation of the physical storage device of the data it is the latter that will be discussed here.
Media degradation to hard drive and disk is the physical lifecycle of all magnetic storage products and to be expected.
Hard drive media has grown in capacity to levels not imagined just a few short years ago during the 50 years of deployment the actual underlying principle is still fundamentally at the core of the technology that is a circular a substrate usually made from glass these days covered in magnetic coating, it is this coating to which we apply the term degradation, the surface obviously like the rest of the complete system (HDD) has a finite life often given as MTBF (Mean Time Between Failure) or start stop counts, as the hard drive ‘ages' the magnetic surface or magnetic domains on the hard drive start to lost their magnetic properties or completely fail, this is often then refereed to as a bad block in user terms, when the hard drive starts to degrade the head stack assembly will try for a certain number (n) times depending the model, firmware, and operating system retries then will either ‘give up' or mark as bad.
Systems and technology in or lab are able to look at each 512k sector block and where the media has become degraded utilising a special piece of hardware sectors which would ordinarily be unreadable are now accessed using a ECC Error correcting algorithm and read previously unread sectors, this technology creates a fuller recovery and is important for an data recovery to be successful.
At the beginning of the this article the statement was made that it was to be expected that the media would degrade and to some computer users this may seem alarming or incorrect to further explain this a brief hard drive manufacture process will help.
As stated earlier hard drives are comprised of a platter which is coated in a magnetic material this coating process is not without difficulties following a surface examination of the drive surface and passing the Q/A process the hard drive is factory formatted, during this process many bad ‘defects' are discovered which help create a map of the surface these ‘bad' sectors are not to be used by the hard drive at all, additionally to this the firmware has provision for what are classed as growing defects, these are bad sectors of the hard drive which have occurred during it operational life and to a degree the hard drive has the facility to ‘swap' or replace these new degraded sectors, of course it has a finite pool of resources to do so however it suffices for normal operator use in most cases.
Data corruption in a logical sense can be defined as the failure to transmit and then receive a facsimile of data with 100& accuracy, be that over a network to and from a storage device or otherwise.
Data sent to degraded hard drive media may corrupt the data, however there some safe guards to try and prevent this from happening call CRC cyclic redundancy check , basically a packet of data is sent to target then a short bust of communications check whether the transmitted data is correct or not.
Computer users may actually receive a CRC error if there hard drive becomes degraded or corrupt other errors can be I/O error no disk access.
If you have a degraded hard drive, disk, server or other such storage device then please get in touch with us as further use will make the problem much harder to remedy, switch off the media and have our labs collect, diagnose and perfrom hard drive recovery for you today