Does formatting slice 2 (backup) destroy disk geometry?

I am a new Unix Sys Admin who is learning mostly from books with minimal classroom training (ie: no certificates, training is largely hands-on, conducted at work). I work with Solaris 8 through 10, and with some fairly outdated hardware. In my work restoring old workstations I have been instructed to avoid formatting or "newfs-ing" slice 2 (which is reserved for "backup" in our systems, marked with flag "wu"); I am told this will destroy the "disk architecture" or "disk geometry" and render it unusable. Despite the warning, I have made the error of formatting slice 2 (using the "format" command), and while the partition spans the entire disk (per our partition tables), I was informed that I have destroyed the disk in the process. To make matters worse, I built a file system on slice 2 with "newfs."

I have done lengthy research online trying to determine exactly what disk geometry or disk architecture is and how it is possible that software can destroy a physical disk but I am at a loss. I understand that slice 2 is historically "reserved" and spans the entire disk; what I do not understand is how altering this slice can destroy a disk.

Can anyone shed any light on this argument? Or better yet, can anyone tell me how to test this theory or recover from the damage I have caused? Is this just an antiquated idea with "historical" significance only or have I really and truly destroyed a piece of hardware with a simple command?

Thanks in advance!

You did not physically destroy the disk. You destroyed any data that was in the various partitions on the disk by creating a filesystem on slice 2 which was set to span the whole disk. There is nothing stopping you using disk in the future.

Thank you for the response, fpmurphy. Based on your response, I am assuming that the way to use this disk in the future is to start fresh by formatting and rebuilding partitions?

I really appreciate your response; do you by any chance know where I can find some documentation that supports your assertion that the disk is usable? I would like to bring this information to my trainer. Have you ever heard of anyone else making a claim such as his? I really want to track down some more info on this case but haven't had much luck on my own.

If anyone has any resources describing disk architecture (and its non-volatile nature) I would find them most helpful; I can only seem to find elementary drawings and explanations of the physical disk parts while, based on the training I have received, there is supposedly some sort of software or firmware which allows the system to communicate with the disk and which is able to be deleted inadvertently by inexperienced admins.

Thanks again!