How can tags be saved only to the database leaving files untouched?

[harrylentil]

I would like updated tags to only be saved to the MB database and not the MP3 files. Is that possible?
It is because my music collection is on many - about a dozen - backup copies all exactly the same and I don't want them getting out of sync, or have to copy a 1.4TB set of files to 12 hard drives including the offsite ones. Or take the risk that one or more MP3 files gets silently corrupted in an update and replace operation across a USB cable. Or a proportion of albums being misidentified by the tagging service and MP3 files updated with incorrect information. I'm mainly thinking about auto-updating missing genre tags across the whole collection and I don't yet know how to do that either but one question at a time.

[phred]

Custom tags can be saved to MB's database. Normal/Regular tags get saved where they're supposed to get save to - the proper tag field embedded in the music file.