Oracle Restart 11gR2
Oracle Restart 11gR2
Oracle Restart adds a lightweight clusterware functionality to a single instance database. If the instance crashes, Oracle Restart brings it up, monitors it ans so on. And by the way, this is called “Grid Infrastructure” istead of CRS as in earlier Oracle releases. So you have to install two Oracle Homes – one each for grid and the rdbms.
When there is Grid, there is srvctl, of course. The grid infrastructure comes with srvctl. Here is how you check what is running from a specific Oracle Home:
oracle@raclinux1 ~# srvctl status home -o /u01/oracle/product/11gR2/db1 -s state.txt
Database d112d1 is running on node raclinux1
The above command create a file called state.txt.
oracle@raclinux1 ~# cat state.txt
db-db
It shows the database name – DB.
This is done on a single instance Oracle database; not a cluster. But the grid infrastructure looks and feels like a cluster. Here are some more commands to check status:
oracle@raclinux1 ~# srvctl status listener
Listener LISTENER is enabled
Listener LISTENER is running on node(s): raclinux1
oracle@raclinux1 ~# srvctl status asm -a
ASM is running on raclinux1
ASM is enabled.
A bunch of new processes suppor this grid infrastructure:
oracle 19046 1 0 18:13 ? 00:00:03 /u01/oracle/product/11gR2/grid1/bin/ohasd.bin rebootoracle 19487 1 0 18:15 ? 00:01:14 /u01/oracle/product/11gR2/grid1/bin/oraagent.bin
oracle 19502 1 0 18:15 ? 00:00:01 /u01/oracle/product/11gR2/grid1/bin/tnslsnr LISTENER -inheritoracle 19656 1 0 18:15 ? 00:00:01 /u01/oracle/product/11gR2/grid1/bin/cssdagent
oracle 19658 1 0 18:15 ? 00:00:02 /u01/oracle/product/11gR2/grid1/bin/orarootagent.binoracle 19674 1 0 18:15 ? 00:00:01 /u01/oracle/product/11gR2/grid1/bin/ocssd.bin
oracle 19687 1 0 18:15 ? 00:00:00 /u01/oracle/product/11gR2/grid1/bin/diskmon.bin -d -f
Let’s see what happens when you kill the instance.
oracle@raclinux1 ~# ps -aef | grep pmon 14225 13768 0 23:15 pts/7 00:00:00 grep pmon 19866 1 0 18:16 ? 00:00:00 asm_pmon_+ASM
oracle 26965 1 0 20:53 ? 00:00:00 ora_pmon_DB
oracle@raclinux1 ~# kill -9 26965
This will, of course, crash the instance. Let’s chck after some time:
oracle@raclinux1 ~# ps -aef | grep pmon 14315 1 0 23:15 ? 00:00:00 ora_pmon_DB
oracle 14686 11492 0 23:17 pts/2 00:00:00 grep pmon 19866 1 0 18:16 ? 00:00:00 asm_pmon_+ASM
Where did the pmon come from? Didn’t the instance just crash?
The instance was restarted by Oracle Restart.
What if you want to just keep the instance down, e.g. during a maintenance. Well, just shutdown normally; the instance will stay down. When you are ready, start the instance using either SQL*Plus or srvctl:
oracle@raclinux1 ~# srvctl start database -d DB
Remember, DB is a single instance database.
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