[BBLISA] Definition of dump levels?

[Brian O'Neill]

Not to belabor the point, but I think part of the confusion is that in 
the history of backups, they were once called "differential incremental" 
  (only changes since last backup of any kind), and "cumulative 
incremental" (changes since last full), and Netbackup still uses this 
terminology.

Legato Networker does not have any documented "differential". The 
"incremental" level is basically a level beyond level 9 - a perpetual 
"only changes since last backup". Otherwise it uses the dump-style 
levels through which you can get all the old semantics. They also add a 
"consolidate" which doesn't perform a backup, but instead merges all 
non-full backups with subsequent backups and produces a new saveset 
which is in essense a full backup.

Not that I trust Wikipedia, but it agrees with my "classic" definitions:

http://en.wikipedia.org/wiki/Incremental_backup

I've not used the other products mentioned, but I did find a page on 
Brightstor ARCserve that seems to indicate it uses my classic definitions:

http://www.open-mag.com/1226339824.shtml

Bacula I believe uses my definitions as well (although they don't 
document it well, but the page for in on Backup Central agrees:

http://www.backupcentral.com/components/com_mambowiki/index.php/Bacula
)

Amanda I think uses simple dump levels.

And I checked BackupExec - I expected it to have the same definitions as 
NetBackup, but this support document says otherwise:

http://seer.support.veritas.com/docs/230247.htm

Since an Incremental resets the Archive bit, a subsequent Incremental 
would only pick up files where they Archive bit was turned back on - 
i.e. anything change since the last full OR incremental. The 
Differential does not reset this bit, so if you only do Fulls and 
Differentials, then the Diffs would back up everything since the last 
Full. Throw in an Incremental, and this would wreak havoc with your 
Differentials. I think this could be a MAJOR source of confusion with 
backups on Archive Bit OSes.

NTBackup does the same:

http://www.argentuma.com/backup/software/windows-backup.html

So, aside from Netbackup using different terminology, my "classic" 
definitions seem to hold true.

-Brian