Error-checking and Check Disk Options....

I was today asked a question that I cannot answer because I have never used the check disk options in XP, let alone any other operating system.

I was asked if it is safe to use (under Error-checking.... Check Disk Options) Scan for and attempt recovery of bad sectors.... As I said I have never used this "setting" in ANY operating system (Windows)... I understand it "should" find and "recover" bad sectors, but if a program, for example Nero, was on one of these bad spots, would XP move it??? Would it then mark it as a bad "spot" on the hard disk and therefore not allow any other programs to fall there???

Also when formatting a hard drive ( to prepare it for Windows) is it possible to format the drive with FAT32 and mark the "blocks" bad so nothing will write to them, before installing Windows....

 

Think of a hard drive as composed of a bunch of glass cds , each with a thin layer of rust (ferric{iron} oxide) on them . There is a head which moves over this and orients the ferric oxide particles to record data. Now when they first make the drive, there are going to be some places where the coating just plain is not thick enough to store data. These are "marked" as bad and not used. But over time , and repeated read write cycles the heat of use and magnetizing/ demagnetizing the particles causes the layer to either get a little thinner in some places or fill with particles which do not loose their orientation when you remove (erase) the data and write new stuff there.
These places, the magnetic field becomes so weak that the head cannot read the data.
What checkdisk (and scandisk) or other error checking does is look at each location and test it to make sure that it is readable and writeable ( visualize that it reads the data and stores it in RAM , writes a test phrase there, reads it and then puts the data back ) . If it finds a place where nothing should be that is bad, it just marks it as bad so windows won't put anything there.
Now if it finds a place where it knows data should be but it sees none, what to do? Well that is where recover the bad sector comes in. It uses various techniques to try over and over to recover the data and copy it elsewhere (think of it as going over the area more slowly and thoroughly, looking very closely and seeing what may be there) . Now in reality it will not be an entire program which is in one of these spots. Your hard drive is divided up into cylinders, heads, sectors, and clusters . The size of the clusters is determined when the drive is formatted and is normally something like 4KB and the data may be just a few bits .

Normally, checkdisk or similar runs as part of the format. Marking the bad areas and adjusting cluster placement as needed.