The main disadvantage of #1 is that lgwr will write full blocks to the redo logs for the entire database until the entire backup is finished. If that takes a while and there is significant activity, it can generate tremendous amounts of redo - and archive. Lgwr and the I/O subsystem are doing more work since they are writing more data. This is what I have do when using EMC and BCV splits for backups since it is so fast.
#2 is, in my opinion, better for any "normal" backups - such as to tape. Since only one tablespace at a time is in backup mode, redo and archive generation is minimized. This is especially true if only a relatively small fraction of the database is undergoing significnant transactional activity. The length of time when lgwr is writing full blocks for those transactions is only as long as it takes to back up those particular tablespaces, not all tablespaces. -Don Granaman [OraSaurus - Honk if you remember UFI!] ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Tuesday, October 02, 2001 6:15 AM Hello, Slightly unrelated question... is it better to (in pseudo code) : 1) for each tablespace loop put tablespace in backup mode end loop for each datafile in the database loop copy data file end loop for each tablespace loop put tablespace in normal mode end loop or 2) for each tablespace loop put tablespace in backup mode for each datafile in this tablespace loop copy data file end loop put tablespace in normal mode end loop What I'm doing is (2), but I notice that Rajesh is doing (1). What are the pros and cons of each approach? (I'll probably use RMAN at some point, anyway :0) ). Cheers, g -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Don Granaman INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
