I use Windows NT installed under VMWare. I'm trying to scan partition having size 10GB or greater and get an error message saying "Error reading physical sector". Is it a drive's problem or your software does not support drives more than 8GB?
It could be bad clusters on the drive as well as BIOS/OS that does not support LBA mode problem.
MS-DOS versions prior to 6.0 does not support LBA mode. Some versions of BIOS could report that LBA mode is not supported for larger drives, however actually it does. VMWare v.3.0 is an example. Active@ UNERASER tries read the drive 100 times. In case of read failure it reports this problem.
Make sure that you boot your system using the proper version of DOS. If it is MS-DOS then version must be 6.0+. In most cases you do NOT need to tell Active@ UNERASER to force LBA mode, because if BIOS supports it, Active@ UNERASER does it automatically, giving you access to larger sized hard drives.
If BIOS reports that LBA mode is not supported, Active@ UNERASER uses standard Int13h to access the drive. You could try to force LBA mode by starting Active@ UNERASER with a parameter -LBA, for example:
A:\>UNERASER.EXE -LBA
However it will not help if BIOS actually does not support LBA mode. It usually happens with old versions of BIOS. In this case you can try to take out HDD and plug it to another machine having newer version of BIOS.
In case of your drive has lots of bad clusters, its advisable to save your data onto another physical drive and to get rid of the damaged hard drive.
