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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Multimaster replication as alternative backup
Simple,Clear and Superb explanation.
Thanks Arup.
-----Original Message-----
Nanda
Sent: Wednesday, November 19, 2003 1:10 AM
To: Multiple recipients of list ORACLE-L
VirVit,
You haven't specified Oracle version and your tolerance for data loss. If you can afford to lose the data in the most current redo log file, then I would suggest 9i Data Guard in maximum performance mode (or Standby in 8i) solution over the MM replication. The DG solution does not affect the primary database performance. You can backup the standby database and use it for recovery of the primary, too.
If you can't afford to lose any data, then you can still use the DG Maximum Protection (in 9i) mode, but it will affect the performance to some extent. However, in this case (no data loss) you have to enable MM Synchronous Replication as opposed to the default Asynchronous mode. In the Synch mode, the performance is worse compared to the Max Protection DG solution.
Here is a summary of the options:
Oracle 8i
|
+-> Last redo data loss ok => Standby Database ~~ Performance=BEST
+-> LAst redo data los NOT ok => MM Synchronous Replication ~~
Performance=VERY BAD
Oracle 9i
|
+-> Last redo data loss ok => Data Guard Max Performance Mode ~~
Performance=BEST
+-> LAst redo data los NOT ok =>
|
+-> Option 1: MM Synchronous Replication ~~ Performance=VERY BAD
+-> Option 2: Data Guard Max Protection Mode ~~ Performance=BAD
Therefore, you are better off using DG (or standby in 8i).
Pros:
(1) You can use standby datafiles to recover primary database
(2) You can take RMAN backups from the standby, reducing the CPU cycle
requirements in primary
Cons:
(1) In Max Protection Mode, the primary also halts if the standby has a
problem; not truly a HA solution. Ideally you need three or more servers -
one primary and two standbys to work perfectly => high cost
Summary: If your management can live with the loss of the last redo, your best option is DG Max Performance (or Standby, in 8i), IMHO.
HTH.
Arup Nanda
www.proligence.com
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Arup Nanda INET: orarup_at_hotmail.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_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). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Sami INET: saminathans_at_myrealbox.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_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).Received on Sun Dec 14 2003 - 09:09:25 CST
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