Problems with incr. snapshots if configuration was modified

[Jean-Peer Lorenz]

Using nssbackup 0.2-0 rc8.

Following behavior was discovered:

1. A backup was created and some files were excluded (e.g. by the maximum size option) from this backup.
2. the setting causing the exclusion is now disabled for later backups (i.e. now files of any size should be backed up)
3. incremental backups created do not include the files that were excluded in step 1)

This is a bug: files that are not stored in prior backups must be stored in they are no longer excluded.

[Jean-Peer Lorenz (peer.loz)]

Unfortunately, this is a bug related to TAR's incremental feature. TAR stores files that are excluded from a backup in the snapshot file (snar file) as 'Not included'. If this exclusion is no longer valid in later backups, TAR does not include such 'new' files since it treats them as not changed since the last backup. The TAR algorithm (version 1.22) is not able to distinct between

1) file was 'Not included' because it is on the excludes list and
2) file was 'Not included' because it hasn't changed since tha last backup.

Conclusion: hard to fix and probably won't fix in nssbackup 0.2.

[Jean-Peer Lorenz (peer.loz)]

This behavior of TAR causes some more problems:
* when merging snar files in order to remove snapshots, excluded files are not found in earlier snapshots because they are marked as 'Not included' (this means 'unchanged'). In fact, they were *never* included.