I have several questions re file corruption due to media. Note that I am using MSDOS/Windows.
1. I have a test machine which I have to copy files to using 3.5" floppies. If I copy a large file from machine A to machine B via floppy and then back via another floppy, then 90% of the time the files are different (using FC /B) even though no errors were reported. I now use zip files and about 50% of the time PKUNZIP reports CRC errors and I have to try again.
Don't floppy drives uses CRCs that should prevent this sort of thing? Is the problem likely to be OS, driver or hardware?
2. I have been having problems with a lot of floppies going bad, so I have been reformating and prefering those with few or no errors. I had a floppy that had 1K in bad tracks before reformating, but none afterward. During the formating the drive was obviously doing a lot of retrying but must have eventually been able to format all the sectors.
Is there a way to force format not to use a sector if it has to do any retries at all? Is there a way to make format retain any sectors already marked bad?
3. I was installing XP from a backup copy of the original CD and the install said that about 6 files could not be copied. The machine used had a very old CD drive.
I then copied all the files from CD to disk to make sure that the disk could be read (which it could) - installing using these disk files had the same problem. I read the files of the same CD using another machine and copied them across the network - installing using these files worked fine.
It looks like the files were not being read from CD properly but no errors were reported. Is it possible XP drivers for very old CD drives are no good?