To (briefly?) summarize... (the first two bullets address your original query):
- With TSM, all the active AND inactive versions are (a) always in the silo, (b) only sent across the network ONCE (if you use the progressive-incremental the way it was intended)... extra copies of the same "version" are created via copy pools and/or backupsets and/or image backups. - TSM's database is used to retrieve *only* the versions of files being requested, automatically taking into account all the modifiers used (eg, point-in-time, replace=y/n, etc.). TSM is designed as a "lights-out" application -- no need to attend to the daily/weekly/monthly tape rotations; more simply, use MOVE DRMedia (at the operator's convenience, notwithstanding your site's offsite-vaulting policy for extra copies) to control tapes moving to offsite vault and back (to scratch). - the old G-F-S (grandfather-father-son) of mainframe days involved periodic FULL backups, typically every weekend; this technique consumes huge amounts of both (a) band-width (every new FULL goes across the network), and (b) tapes, just for primary copies (most sites have no time left to create a 2nd copy, so they're totally exposed to restore failure if that only volume fails for any reason!) - FULL+Incremental mentality of Legato & Veritas is, unremarkably, similar to G-F-S -- its main benefit is that it's easy to understand and implement (if you are NOT the operator trying to track down the tapes!); to recover any given file-system requires (a) retrieve the latest FULL, then (b) retrieve all subsequent INCRementals --- that can be alot of extra traffic, not to mention the tricks needed to avoid "losing" any files created and deleted within the same week AND you must know where the tapes are and get them loaded. BTW, if any tape in the series goes bad, the data on that tape could be lost forever -- unless the file's age is such that some previous FULL or INCRemental captured it! HTH! Don France Technical Architect -- Tivoli Certified Consultant Tivoli Storage Manager, WinNT/2K, AIX/Unix, OS/390 San Jose, Ca (408) 257-3037 mailto:[EMAIL PROTECTED] (change aye to a for replies) Professional Association of Contract Employees (P.A.C.E. -- www.pacepros.com) -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] Behalf Of Joni Moyer Sent: Wednesday, March 05, 2003 6:21 AM To: [EMAIL PROTECTED] Subject: progressive backup vs. full + incremental Hello everyone! I was wondering why the full + incremental would result in a longer restore time than the progressive backup methodology? From several co-workers point of view they thought that it would be quicker on the full + incremental because you wouldn't have to go back to the beginning backups of the file and restore all of the incrementals, you would just go back to the most recent full backup and apply the incrementals after that point. When I went to explain the reasoning behind this, I had some problems understanding the concept myself, so I was hoping someone could explain both methods and why they differ in restore time and why progressive is better than the full + incremental. Thank you so much for any help you can lend on this matter! Joni Moyer Systems Programmer [EMAIL PROTECTED] (717)975-8338
