[rdiff-backup-users] Remove (large) files from backup without generating negative diff

[Marcin Zajączkowski]

Hi,

I have a long established backup with some large files which I would
like to move to another directory withing the same backup (or just
remove entirely from the backup) as a clean up of the original disk
space/organization. I would like to avoid extra many GBs in the next
incremental backup session when those files are moved/removed. I don't
need their history - they will be backed up in another way/place.

Firstly, I was plying with removing just related information from
"increments" directory. Unfortunately it made restore/verification
lopped with 100% CPU utilization. I needed to remove all information
about affected files also from extended_attributes.*, file_statistics.*,
etc. I feel it like asking for trouble.

Two questions:
1. Do you know any better way of removing files from a (rdiff-)backup
without generating a "negative" diff in the next backup?
2. Do you see any additional risk with manual manipulation of
rdiff-backup files if --verify and --restore (checked selectively) seem
to work fine?

Marcin