From guy.hammond@avt.co.uk Tue, 02 Oct 2001 07:16:56 -0700 From: "Guy Hammond" Date: Tue, 02 Oct 2001 07:16:56 -0700 Subject: RE: Hot Backup Issue In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: text/plain Title: RE: Hot Backup Issue That makes sense, I just wanted to check :0) And of course, transactions in other tablespaces would be writing redo as normal. The overall level of redo generated would surely be less, tho'? Because say you had 5 tablespaces and put them all into hotbackup mode. Then the 5th tablespace would be writing full blocks to the redo log for all the time it took to copy the datafiles of the first 4, rather than for just the time it took to copy itself if you only put tablespaces into backup mode while they were actually having their datafiles copied? And when recovering, Oracle doesn't mind that some redo information will be full blocks, and some not, if a transaction spans multiple tablespaces, one of which was in hotbackup mode and the rest not when the transaction was committed?   Thanks,   g -----Original Message-----From: Hallas John [mailto:John.Hallas@btcellnet.net]Sent: Tuesday, October 02, 2001 1:45 PMTo: Multiple recipients of list ORACLE-LSubject: RE: Hot Backup Issue Guy, I would have thought 2) was best as you are reducing the concurrency (I think that is the right word) of redo log activity. As each tablespace is in backup mode it writes the full block to the redo log when any changes are made. On the assumption that all tablespaces are being written (albeit infrequently) during the period of hot backup it is better to alter each tablespace, copy it then alter online again so that only 1 tablespace at a time is having full blocks of changed data writing to the redo logs. The overall level of redo will be the same but contention (ah ha  - better word) will be reduced John -----Original Message----- From: Guy Hammond [mailto:guy.hammond@avt.co.uk] Sent: 02 October 01 12:15 To: Multiple recipients of list ORACLE-L Subject: RE: Hot Backup Issue 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: Guy Hammond   INET: guy.hammond@avt.co.uk 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: ListGuru@fatcity.com (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). **********************************************************************This email and any attachments may be confidential and the subject oflegal professional privilege. Any disclosure, use, storage or copyingof this email without the consent of the sender is strictly prohibited.Please notify the sender immediately if you are not the intendedrecipient and then delete the email from your inbox and do notdisclose the contents to another person, use, copy or store theinformation in any medium.**********************************************************************