Oracle RAC Administration – Part 5: Administering the Clusterware and ASM Storage

Brief intro

Oracle’s shopping spree has resulted in a 30% increase in earnings; (Siebel was the hero by the way). Oracle is setting the stage, aggressively moving into the BI world. Business Object will eventually be the next in line. I even predict that educational software, LMS (Learning Management system) as it is called in educational institutions, will be the next in line. I muse on that possible strategic intent in my blogpost. So what would it all mean? Well, one thing I’m pretty sure of–a lot more Oracle database deployments. RAC and GRID computing are soon becoming inseparable terms, and Grid or Utility Computing is where we are heading.

OK let’s now get into our administration and take a look at administering our OCR.

Administering the OCR Using OCR Exports

It’s one thing to have automated backups, which are created by the OCR backup files but it also requires that you export the OCR contents both before and after any changes that you may bring to the configuration files. Changes can vary from task to task, such as adding nodes, deleting nodes from your RAC environment, modifying the Clusterware resources, creating a database etc. These modifications are accomplished using the ocrconfig -export command, which will export the contents of our OCR to a file format.

Unresolvable issues can be fixed by using the –import flag. Let’s take a look at various configurations, starting with UNIX configurations.

Importing Oracle Cluster Registry Content on UNIX-Based Systems

Note: Do note that most of the configuration changes to the OCR contents also cause the file and database object creation. Moreover, not all of these changes are restored when you restore the OCR. Performing an OCR restore in order to revert to an older working configuration will invariably fail, and it goes without saying, your RAC will be out of sync.

OK now let’s take a look at the import procedures of our OCR on UNIX-based systems:

• Select the OCR export file that you want to import by using the following command:

   ocrconfig –export myfile
  
  

  
  
• Stop the RAC Clusterware on all nodes by going to the bin directory of your cluster and doing:

    ../bin/crs stop
  
  

  
  
• Now we have to carry out the import by supplying the following commands. Here myfile will be the file from which you want to import your OCR configuration data

   ocrconfig –import myfile
  
  

  
  
• Now restart your Oracle Clusterware on all nodes.
  
• As an additional check, you should (as I’ve mentioned before) always run the Cluster Verification Utility (CVU) for the integrity of our RAC. Doing a cluvfy comp ocr -n all [-verbose] will retrieve a list of all the nodes in the cluster.

Importing Oracle Cluster Registry Content on Windows-Based Systems

Use the following procedure to import the OCR on Windows:

• Check the OCR export file that you want to import by running the ocrconfig – showbackup command.
  
• Stop the OCR on all nodes in your RAC cluster. On Windows, you can use the Service Control Panel to stop the following services: OracleClusterVolumeService, OracleCMService, OracleEVMService, OracleCSService, and the OracleCRService.
  
• Now import the export file using the command ocrconfig –import from any one of the nodes.
  
• Restart all of the services on all of the nodes that you just modified.
  
• Run the command Cluster Verification Utility (CVU) to check the integrity of all of the affected nodes. You could also list them all by using –n flag. Typing the following should give you a verbose output of all the listed nodes.

   cluvfy comp ocr -n all [-verbose]
  
  

Administering Storage on RAC

We all know by now that the storage on our RAC resides on shared disks and is thus shared. The datafiles we created (ASM1,ASM2,ASM3) all reside in the ASM (Automatic Storage Management) disk group. They can, however, also reside on raw devices. (We won’t get into that). If you follow the OFA, then you will create adequate log files (two at least) that also reside on the shared storage. We also had our mounted disk, specially made for the spasmfile, or SPFILE. There is also an option to use and store client-side parameter files (PFILES). We followed Oracle’s advice and stuck to the SPFILE and ASM. There may be situations or cluster scenarios where that might not be possible. Do refer to appropriate Admin Guide for further reading.

Now let’s take a quick look at administering our ASM instance with the srvctl command line tool, our powerful SVRCTL utility.

Administering ASM Instances with SRVCTL in RAC

Use the following command to add configuration information to an existing ASM instance:

srvctl add asm -n mynode_name -i myasm_instance_name -o myoracle_home

If, however, you choose not to add the –I option, then the changes are propogated throughout the entire ASM instance pool.

To remove an ASM instance, use the following syntax:

srvctl remove asm -n mynode_name [-i myasm_instance_name]

In order to enable an ASM instance, use the following syntax:

srvctl enable asm -n mynode_name [-i ] myasm_instance_name

In order to disable an ASM instance use the following syntax:

srvctl disable asm -n mynode_name [-i myasm_instance_name]

Note that you can also use the SRVCTL utility to start, stop, and get the status of an ASM instance. See the examples below.

To start an ASM instance, do the following:

srvctl start asm -n mynode_name [-i myasm_instance_name] [-o start_options] [-c <connect_str> | -q]

To stop an ASM instance, type the following syntax:

srvctl stop asm -n mynode_name [-i myasm_instance_name] [-o stop_options] [-c <connect_str> | -q]

To list the configuration of an ASM instance do the following:

srvctl config asm -n mynode_name 

To get the status of an ASM instance, see the following syntax:

srvctl status asm -n mynode_name

Conclusion:

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