May depend on the type of tape and how it was "erased." With floppies and hard drives, the files are deleted by changing only the file allocation table, the file's contents are still there. The table then allows the space being occupied by the file to be reused. If the file's space is overwritten then undelete won't work.
With tapes, there may not be a file allocation table, sometimes called a header for tapes. The file is written to the tape sequentially. If the tape was truly erased then the space formerly occupied by the file is erased by, usually, changing the bits to all ones or zeros.
If your backup program created a tape header and the erase only deleted that header and not the file, then it can be recovered but I don't know of a program to do that off the top of my head. There are recovery companies that can recover the info. James P. Cottingham
When a man sits with a pretty girl for an hour, it seems like a minute. But let him sit on a hot stove for a minute and it's longer than any hour. That's relativity.
[tab][tab]Albert Einstein explaining his Theory of Relativity to a group of journalists.
