Both programs are what would loosely be called disk integrity checking applications – they take a look at the data and file structures on a hard drive and if they find something is not right, they try to correct it.
Well that’s fine right ?
In most cases it is fine. The problems come when there’s something wrong with the hard drive too…
A data corruption can occur for a number of reasons – for example a program may not terminate correctly, or a loss of power may mean that a file has been incorrectly saved etc. In these cases because there’s nothing wrong with the hard drive, CHKDSK will run correctly and attempt to correct the problem.
However, file and data corruption can also result from the hard drive having bad media issues… This is where parts of the hard drive become progressively more difficult for the computer to access, typical symptoms include –
- Disk access is slower and slower (giving the appearance that the machine is running slowly)
- Some files and folders take a long time to open, if they open at all
- You may see error messages like ‘Delayed Write Failure’
- You may see system messages relating to CRC errors
Running a program like CHKDSK on a hard drive with bad media will take a considerable amount of time (usually several hours) as the system is trying to read and write data to problematic areas of the hard drive. This will result in the creation of many .CHK files – these are orphaned & often incomplete versions of the original files which can not longer be accessed. It will also place considerable stress on the heads of the hard drive as they are continually trying to re-read and re-write data to these bad areas of the hard drive. In its worst case this can cause a head crash and your data will be lost forever.
What to do if you have a hard drive like this? – A professional data recovery company will use a hardware approach to recovering data from drives with bad media – they will have some physical equipment capable of dealing with it. If your talking to a company that is suggesting using a software approach to recover your data, look elsewhere.