Guenadi N Jilevski's Oracle BLOG

Finally, it’s that time again – the birth of a new versionof Oracle – 11g Release 2. Being Release 2, it does not have as much bells and whistles as the 11g.

I downloaded it immediately and started installation. Some of the gee-whiz features of this release are:

(1) Editions
(2) ASM Filesystem
(3) Oracle Restart
(5) Columnar Compression

I have been beta testing this for some time; so I had seen previews of the release. Continuing the previous seriese.

A little bit about Oracle Restart. It adds a lightweight clusterware functionality to a single instance database. If the instance crashes, OR brings it up, monitors it ans so on. And by the way, this is called “Grid Infrastructure”. 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@oradba1 ~# srvctl status home -o /opt/oracle/product/11gR2/db1 -s state.txt
Database d112d1 is running on node oradba1

The above command create a file called state.txt.

oracle@oradba1 ~# cat state.txt
db-d112d1

It shows the database name – D112D1.

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@oradba1 ~# srvctl status listener
Listener LISTENER is enabled
Listener LISTENER is running on node(s): oradba1
oracle@oradba1 ~# srvctl status asm -a
ASM is running on oradba1
ASM is enabled.

A bunch of new processes suppor this grid infrastructure:

oracle   19046     1  0 18:13 ?        00:00:03 /opt/oracle/product/11gR2/grid1/bin/ohasd.bin reboot
oracle 19487 1 0 18:15 ? 00:01:14 /opt/oracle/product/11gR2/grid1/bin/oraagent.bin
oracle 19502 1 0 18:15 ? 00:00:01 /opt/oracle/product/11gR2/grid1/bin/tnslsnr LISTENER -inherit
oracle 19656 1 0 18:15 ? 00:00:01 /opt/oracle/product/11gR2/grid1/bin/cssdagent
oracle 19658 1 0 18:15 ? 00:00:02 /opt/oracle/product/11gR2/grid1/bin/orarootagent.bin
oracle 19674 1 0 18:15 ? 00:00:01 /opt/oracle/product/11gR2/grid1/bin/ocssd.bin
oracle 19687 1 0 18:15 ? 00:00:00 /opt/oracle/product/11gR2/grid1/bin/diskmon.bin -d -f

Let’s see what happens when you kill the instance.

oracle@oradba1 ~# ps -aefgrep pmon
oracle   14225 13768  0 23:15 pts/7    00:00:00 grep pmon
oracle   19866     1  0 18:16 ?        00:00:00 asm_pmon_+ASM
oracle   26965     1  0 20:53 ?        00:00:00 ora_pmon_D112D1
oracle@oradba1 ~# kill -9 26965

This will, of course, crash the instance. Let’s chck after some time:

oracle@oradba1 ~# ps -aef|grep pmon
oracle   14315     1  0 23:15 ?        00:00:00 ora_pmon_D112D1
oracle   14686 11492  0 23:17 pts/2    00:00:00 grep pmon
oracle   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@oradba1 ~# srvctl start database -d d112d1

Remember, D112D1 is a single instance database.