Win XP Home SP.3

I'd like to know how the volume serial number is calculated/allocated during a format and whether the user can influence the calculation/allocation in any way.

ThanksThe serial number is a 32-bit number determined by the date and TIME on the current computer at the time of a disk's formatting. The low order 16-bit word is calculated by TAKING the month and day value and converting them to hexadecimal. The number of seconds and 100ths of seconds are also converted to hexadecimal and added to month & day value. The high order word is calculated by taking the HOURS & minutes value and converting them to hexadecimal. This is then added to the hexadecimal value of the year.

Here is a diagram showing how the additions were done that resulted in a Volume Serial of 2514-1df4



I suppose you could try to set your system date to produce the desired number, and do the format at just the right time to catch the 100ths of seconds, but there are LOTS of utilities out there to change a volume serial number. It involves direct disk editing, so I'd back up all your data first. Google for "Volume Serial Number Editor" for example.

It is not possible to decode the volume serial number and verify the format date/time unless you have some of the information already. If you know the year the disk was formatted, it is then possible to calculate the time. Calculating the date is a little more difficult as you need the exact seconds and 100ths of a second and vice versa. If you know the date, then it is possible to calculate the format time.


Thank you Dias, I had thought that the date/time would be involved, I already use a third-party utility to change vol ser numbers..

Only surprise is that you haven't come back with a VB script or Batch script to answer my query. LOL the one time I needed to change a disk serial, I resorted to Norton Disk Edit.

Boy was I surprised that I didn't manage to screw something up terribly... Although I learned a bit about the MBR and so forth that day.