The only "sanctioned" method of backups requires either full db, else transaction logs (diff or incr). The very best explanation of the choices involved with Exchange are in the Install & User's Guide; also, see the Redbooks for backing up databases with TSM -- and the many posts on this forum from Del Hoobler.
Most dba's like daily FULL (online) backups -- regardless of the flavor; that goes for Exch, SQL-server, Oracle (including SAP/R3 & Peoplesoft). The larger the db gets, the more important it becomes to minimize the data loss (to under 24-hours) between FULLs; mission-critical db's were on HA machines, redo/transaction logs get dumped and copy-pooled every 3-4 hours (depending on volume/time -- using filesystem monitor to watch for 30% of capacity). RMAN's not-so-great block-level incrementals have been slow on restore; the incr speed is wonderful, getting good restore speed has been very difficult/frustrating... if you really want block-level incrementals (for ANY db, consider anybody's snapshot -- like Veritas, EMC-TimeFinder, etc.) All things considered, you must evaluate the db-size and tape media involved in context with your restore SLA; mostly, the dozen or so customers I've had on Exchange go for daily or weekly fulls, plus (sometimes) incrementals in between... but that was with Exch-5.5, smaller IS standards (always less than 100 GB, strive to keep IS under 50GB, standard was 35 GB then put in change control to create an additional server). Now, with Exch-2K, the reliability & availability being much greater(?), your IS will be best capped around 100GB, again depends on SLA for restore. As your mileage will vary, per network, tape devices, and TSM server capability, measure your environment for desired SLA --- on a shared LAN, we readily achived 18 GB/Hr restore speeds (old 3575, 100 Mbps production LAN during the business day at 3pm). Differential plus FULL versus several incrementals after restoring FULL; BUT, wait... with Exc-2K, you don't need to restore the entire IS, just the group that holds the mail objects you are after ... so, given 80-95% restores are for mailbox of individual items, you're passing more tape than actually restoring. Logs are 5MB, number depends on how much activity you have; for my money's worth, I'd advise (a) daily FULL (perhaps periodic INCR/DIFF during the day, or (b) weekly FULL with daily DIFF (to consolidate logs for a given week -- in case you *must* do a restore, provided the number is "manageable" as determined by your restore SLA!) In our case, we typically saw less than 100 log files per day; for a week, we'd accumulate maybe 500 or so. We used a separate storage pool, so each day's data was separated only by other Exch. nodes on the same TSM server). Good luck; you're gonna need to do your own homework -- there are no shortcuts to due dilligence (on the customer's expectations and your infracstructure to support any given SLA), especially for data base apps! Don France Technical Architect - Tivoli Certified Consultant San Jose, Ca (408) 257-3037 mailto:[EMAIL PROTECTED] (P.A.C.E. -- www.pacepros.com) -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED]]On Behalf Of DEAN LUNDGREN Sent: Friday, May 24, 2002 12:42 PM To: [EMAIL PROTECTED] Subject: TDP for Exchange and TSM sizing We are planning to convert out mail from Groupwise to Exchange 2000 and are trying to estimate the load to TSM. We have 2000 users on Groupwise and a database of about 70 GB. We are told to expect the Exchange to be three time larger or about 200GB. >From what I've read about TDP for Exchange we can choose to do fulls, then either perform differentials or incremental on the log until the next full. How big is the log compared to the database? Some input we have received is to expect the whole database to be backed up, which makes no sense to me. Otherwise the TDP Exchange agent is worthless. We have a 60 day retention policy for our mail and the implications to our tape usage would be too much if we have to backup the whole thing. Can anyone share the size of the Exchange database and how much log space changes. Please let me know whether you've chosen to use differential or incremental and how often you do fulls. Thanks, Dean Lundgren Sr. System Engineer (740)322-5479
