Sunday 13 October 2013

RMAN Active/Standby Duplicate Hangs

RMAN Active/Standby Duplicate Hangs

Recently, I was doing a DataGuard set-up for 11gR2 database. After doing the preliminary steps and database level preparation, I started the RMAN Standby Duplicate command.
I wait for long, almost 4 hours, but still the datafile copy didn't start from primary to standby(source to target).

Similar issue I have faced earlier too for 11gR1 database while doing implementation of DR Site for eBusiness Suite, OBIEE and some Oracle Retail Applications(RMS, WMS, RIB, SIM etc), but documenting here this time for benefits.

Connect to Primary(Source) database using RMAN:

$ RMAN
RMAN> CONNECT TARGET;
RMAN> SHOW ALL;

Check what is the setting for BACKUP OPTIMIZATION.

Switch backup optimisation off before starting the RMAN Duplicate command, otherwise, RMAN would internally decide the optimization plan for the duplicate process.
This would take lot of time if the DB Size is high to start the datafile copy. Database size in this case was 1.7TB.

In Primary(Source) Database execute the following command:
RMAN> CONFIGURE BACKUP OPTIMIZATION OFF;

---- Revert back the change in Primary when RMAN duplicate finished.

This solve the issue for me, but would like to highlight few more reasons which can cause RMAN Active Duplicate to hang.

1. SGA and Pool Size can Impact your Duplicate Performance

Large pool size plays an important role in RMAN Recovery, SGA decides how many channel you can use your RMAN Duplicate command.

I was having ample sizing for the primary/standby database, so set the following in both:
*.sga_target = 14G
*.shared_pool_size = 3G
*.shared_pool_reserved_size = 300M
*.streams_pool_size = 150M
*.java_pool_size = 1G
*.pga_aggregate_target = 20G
*.result_cache_max_size = 150M
*.db_cache_size = 2G
*.large_pool_size=300M
*.db_keep_cache_size = 500M
*.db_writer_processes = 3
*.processes = 2500
*.sessions = 5000
*.open_cursors = 1500

2. RMAN Duplicate can hang if Compatible setting in both target and auxiliary database is not same. Refer MOS Note 816094.1 for the same. 

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