Hemesh RAC Edition: March 2011

Thursday 17 March 2011

Stopping the Oracle RAC 10g Environment

The first step is to stop the Oracle instance. When the instance (and related services) is down, then bring down the ASM instance. Finally, shut down the node applications (Virtual IP, GSD, TNS Listener, and ONS).

$ export ORACLE_SID=orcl1 $ emctl stop dbconsole $ srvctl stop instance -d orcl -i orcl1 $ srvctl stop asm -n linux1 $ srvctl stop nodeapps -n linux1

Starting the Oracle RAC 10g Environment

The first step is to start the node applications (Virtual IP, GSD, TNS Listener, and ONS). When the node applications are successfully started, then bring up the ASM instance. Finally, bring up the Oracle instance (and related services) and the Enterprise Manager Database console.

$ export ORACLE_SID=orcl1 $ srvctl start nodeapps -n linux1 $ srvctl start asm -n linux1 $ srvctl start instance -d orcl -i orcl1 $ emctl start dbconsole

Start/Stop All Instances with SRVCTL

Start/stop all the instances and their enabled services. I have included this step just for fun as a way to bring down all instances!

$ srvctl start database -d orcl  $ srvctl stop database -d orcl

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A brief Summary of Steps to Start / Shutdown RAC/ASM Setup (Oracle 11g):

Shutdown

1. shutdown database
srvctl stop database -d  "that will shutdown ALL running instances of "
srvctl stop instance -d  -i  "that will shutdown only specified instance of , other running instances will continue to run"

2. shutdown ASM
srvctl stop asm -n  "run it for every rac node one-by-one"

3. shutdown nodeapps
srvctl stop nodeapps -n  "run it for every rac node one-by-one"

4. Shutdown crs processes
crsctl stop crs
Startup

1. crsctl start crs -> that will start crs processes (HA-Engine), NodeApps, then ASM then Database's Instances then HA-Services (if any)

Thursday 10 March 2011

Migrate OCR and Voting Disk from External to High Redundancy disk group in Oracle ASM

Multiple OCRs and vote disks on ASM in Oracle 11gR2 « Guenadi N Jilevski's Oracle BLOG

Voting Disk and OCR in 11gR2 On ASM Storage

Having just delivered an Oracle Database 11gR2 RAC Admin course, I’d like to point out some remarkable changes in the way we handle now the important Clusterware components Voting Disk and Oracle Cluster Registry (OCR): Amazingly, we can now store the two inside of an Automatic Storage Management (ASM) Disk Group, which was not possible in 10g.

Then you cannot create more than 1 voting disk in the same or on another/different diskgroup disk when using External Redundancy in 11.2.

The rules are as follows:

External = 1 voting disk

Normal= 3 voting disk

High= 5 voting disk

External redundancy diskgroup depends on the third party hardware vendor to handle the redundancy.

If you want to have the voting disk multiplexed at ASM level then it is recommended you change your redundancy to Normal so that ASM provides this redundancy for you.

The OCR is striped and mirrored (if we have a redundancy other than external), similar as ordinary Database Files are. So we can now leverage the mirroring capabilities of ASM to mirror the OCR also, without having to use multiple RAW devices for that purpose only. The Voting Disk (or Voting File, as it is now also referred to) is not striped but put as a whole on ASM Disks – if we use a redundancy of normal on the Diskgroup, 3 Voting Files are placed, each on one ASM Disk. This is a concern, if our ASM Diskgroups consist of only 2 ASM Disks! Therefore, the new quorum failgroup clause was introduced:

create diskgroup data normal redundancy

failgroup fg1 disk 'ORCL:ASMDISK1'

failgroup fg2 disk 'ORCL:ASMDISK2'

quorum failgroup fg3 disk 'ORCL:ASMDISK3'

attribute 'compatible.asm' = '11.2.0.0.0';

The failgroup fg3 above needs only one small Disk (300 MB should be on the safe side here, since the Voting File is only about 280 MB in size) to keep one Mirror of the Voting File. fg1 and fg2 will contain each one Voting File and all the other stripes of the Database Area as well, but fg3 will only get that one Voting File.

[root@uhesse1 ~]#  /u01/app/11.2.0/grid/bin/crsctl query css votedisk
  ##  STATE    File Universal Id                File Name Disk group
  --  -----    -----------------                --------- ---------
   1. ONLINE   511de6e64e354f9bbf4be318fc928c28 (ORCL:ASMDISK1) [DATA]
   2. ONLINE   2f1973ed4be84f50bffc2475949b428f (ORCL:ASMDISK2) [DATA]
   3. ONLINE   5ed44fb7e79c4f79bfaf09b402ba70df (ORCL:ASMDISK3) [DATA]

Another important change regarding the Voting File is that it is no longer supported to take a manual backup of it with dd. Instead, the Voting File gets backed up automatically into the OCR. As a New Feature, you can now do a manual backup of the OCR any time you like, without having to wait until that is done automatically – which is also still done:

[root@uhesse1 ~]# /u01/app/11.2.0/grid/bin/ocrconfig -showbackup

uhesse1 2010/10/06 09:37:30 /u01/app/11.2.0/grid/cdata/cluhesse/backup00.ocr

uhesse1 2010/10/06 05:37:29 /u01/app/11.2.0/grid/cdata/cluhesse/backup01.ocr

uhesse1 2010/10/06 01:37:27 /u01/app/11.2.0/grid/cdata/cluhesse/backup02.ocr

uhesse1 2010/10/05 01:37:21 /u01/app/11.2.0/grid/cdata/cluhesse/day.ocr

uhesse1 2010/10/04 13:37:19 /u01/app/11.2.0/grid/cdata/cluhesse/week.ocr

Above are the automatic backups of the OCR as in earlier versions. Now the manual backup:

[root@uhesse1 ~]# /u01/app/11.2.0/grid/bin/ocrconfig -manualbackup

uhesse1 2010/10/06 13:07:03 /u01/app/11.2.0/grid/cdata/cluhesse/backup_20101006_130703.ocr

I got a manual backup on the default location on my master node. We can define another backup location for the automatic backups as well as for the manual backups – preferrable on a Shared Device that is accessible by all the nodes (which is not the case with /home/oracle, unfortunately ):

[root@uhesse1 ~]# /u01/app/11.2.0/grid/bin/ocrconfig -backuploc /home/oracle

[root@uhesse1 ~]# /u01/app/11.2.0/grid/bin/ocrconfig -manualbackup

uhesse1 2010/10/06 13:10:50 /home/oracle/backup_20101006_131050.ocr