>TSM doesn't allow incrementals based on the Archive Bit because everybody
>can change it. Netbackup offers this method as a default!

Archive bit is used for Windows NT, I believe NetBackup uses ctime on Unix.
There is a choice for NT clients to choose whether or not to use the archive
bit.  If backup by archive bit is not chosen, datetime stamp is used.

>TSM doesn't allow incrementals with "un-true" images. Netbackup offers
>"True" Image Recovery (TIR), but default is without TIR!

Personally I don't like True Image Recovery, because if a file was deleted
and it was accidental, it may need to be restored.  The TIR backup will not
include the files that have been deleted.  I don't think this is a default
because it is probably not the preferred method for most people.  There are
cases where a TIR backup / restore option would come in handy, but for most
backups, I stay away from it.

>I think we must use Netbackup without Archive Bit and with TIR to do
>professional backups as we can do with TSM.
>But Netbackup has a bug, and an incremental with TIR backs up almost an
>entire server, i. e. more than 200 GB instead of some 5-10 GB.

Vertias NetBackup will definately give you professional backups.  In the
above example you can do a full backup and differential incremental backups.
The differential incremental will backup only the changed files since the
last full.  So far as the TIR incremental, you need to make sure that you
are doing a differential and not a cumulative incremental. 

I just ran a couple of TIR backups as a test.  The differential incremental
backed up fewer files than the full backup. 

What version of NetBackup do you have?