Posts Tagged High Availability
With a Data Guard Configuration in Maximum Performance protection mode, don’t go to Maximum Protection directly, because that leads to a restart of the primary database:
DGMGRL> show configuration; Configuration - myconf Protection Mode: MaxPerformance Databases: prima - Primary database physt - Physical standby database physt2 - Physical standby database (receiving current redo) Fast-Start Failover: DISABLED Configuration Status: SUCCESS DGMGRL> edit configuration set protection mode as maxprotection; Operation requires shutdown of instance "prima" on database "prima" Shutting down instance "prima"... Database closed. Database dismounted. ORACLE instance shut down. Operation requires startup of instance "prima" on database "prima" Starting instance "prima"... ORACLE instance started. Database mounted. Database opened.
Instead, go to Maximum Availability first and then to Maximum Protection:
DGMGRL> edit configuration set protection mode as maxperformance; Succeeded. DGMGRL> edit configuration set protection mode as maxavailability; Succeeded. DGMGRL> edit configuration set protection mode as maxprotection; Succeeded.
The demo was done with 12c, involving a cascading standby database, but the behavior is the same in 11g already. The odd thing about it is that DGMGRL will restart the primary without warning. Wanted to share that with the Oracle community for years but always got over it somehow.
When you install an 11g RAC database without Grid Control respectively Cloud Control present, this is what the DBCA will give you:
There is one Database Control OC4J Container only, running on host01. Should host01 go down, the Enterprise Manager is no longer available now. We could make that a resource, known to the clusterware and let it failover in that case. But also – and even easier – we can start a second OC4J Container to run on host02 simultaneously like this:
[oracle@host01 ~]$ emca -reconfig dbcontrol -cluster -EM_NODE host02 -EM_NODE_LIST host02 STARTED EMCA at May 14, 2014 5:16:14 PM EM Configuration Assistant, Version 220.127.116.11.0 Production Copyright (c) 2003, 2011, Oracle. All rights reserved. Enter the following information: Database unique name: orcl Service name: orcl Do you wish to continue? [yes(Y)/no(N)]: yes May 14, 2014 5:16:26 PM oracle.sysman.emcp.EMConfig perform INFO: This operation is being logged at /u01/app/oracle/cfgtoollogs/emca/orcl/emca_2014_05_14_17_16_14.log. May 14, 2014 5:16:29 PM oracle.sysman.emcp.util.DBControlUtil stopOMS INFO: Stopping Database Control (this may take a while) ... May 14, 2014 5:16:34 PM oracle.sysman.emcp.EMAgentConfig performDbcReconfiguration INFO: Propagating /u01/app/oracle/product/11.2.0/dbhome_1/host02_orcl/sysman/config/emd.properties to remote nodes ... May 14, 2014 5:16:34 PM oracle.sysman.emcp.util.DBControlUtil startOMS INFO: Starting Database Control (this may take a while) ... May 14, 2014 5:17:33 PM oracle.sysman.emcp.EMDBPostConfig performDbcReconfiguration INFO: Database Control started successfully May 14, 2014 5:17:34 PM oracle.sysman.emcp.EMDBPostConfig showClusterDBCAgentMessage INFO: **************** Current Configuration **************** INSTANCE NODE DBCONTROL_UPLOAD_HOST ---------- ---------- --------------------- orcl host01 host01.example.com orcl host02 host02.example.com Enterprise Manager configuration completed successfully FINISHED EMCA at May 14, 2014 5:17:34 PM [oracle@host01 ~]$ emctl status dbconsole Oracle Enterprise Manager 11g Database Control Release 18.104.22.168.0 Copyright (c) 1996, 2011 Oracle Corporation. All rights reserved. https://host01.example.com:1158/em/console/aboutApplication Oracle Enterprise Manager 11g is running. ------------------------------------------------------------------ Logs are generated in directory /u01/app/oracle/product/11.2.0/dbhome_1/host01_orcl/sysman/log
Not only can I access Database Control at host01 as usual, I can also get it at host02 now:
[oracle@host01 ~]$ ssh host02 Last login: Wed May 14 10:50:32 2014 from host01.example.com [oracle@host02 ~]$ emctl status dbconsole Oracle Enterprise Manager 11g Database Control Release 22.214.171.124.0 Copyright (c) 1996, 2011 Oracle Corporation. All rights reserved. https://host02.example.com:1158/em/console/aboutApplication Oracle Enterprise Manager 11g is running. ------------------------------------------------------------------ Logs are generated in directory /u01/app/oracle/product/11.2.0/dbhome_1/host02_orcl/sysman/log
All this is of course not new, but you won’t find it easy in the docs. That is something from my RAC accelerated course last week in Reading, by the way. Even seasoned RAC DBAs are sometimes not aware of that option, so I thought it might be helpful to publish it here briefly 🙂
Based on the Grid Infrastructure, RAC One Node is a RAC Database with only one instance running. This architecture reduces unplanned as well as planned downtime. If the server crashes that holds the instance of a RAC One Node database, that instance can failover to another node in the cluster automatically. If we need to take down the server (or the clusterware stack there) because of a maintenance task, we can do an Online Database Relocation:
The demo was done with 11gR2 and it is very similar to what I show live during the Oracle University course Oracle Database 11g: RAC Administration about RAC One Node. Hope you like it 🙂