Call now: 252-767-6166  
Oracle Training Oracle Support Development Oracle Apps

 
 Home
 E-mail Us
 Oracle Articles


 Oracle Training
 Oracle Tips

 Oracle Forum
 Class Catalog


 Remote DBA
 Oracle Tuning
 Emergency 911
 RAC Support
 Apps Support
 Analysis
 Design
 Implementation
 Oracle Support


 SQL Tuning
 Security

 Oracle UNIX
 Oracle Linux
 Monitoring
 Remote s
upport
 Remote plans
 Remote
services
 Application Server

 Applications
 Oracle Forms
 Oracle Portal
 App Upgrades
 SQL Server
 Oracle Concepts
 Software Support

 Remote S
upport  
 Development  

 Implementation


 Consulting Staff
 Consulting Prices
 Help Wanted!

 


 Oracle Posters
 Oracle Books

 Oracle Scripts
 Ion
 Excel-DB  

Don Burleson Blog 


 

 

 


 

 

 
 

Oracle High Availability Services (OHAS)

Oracle Tips by Burleson Consulting

December 22, 2009

Staring in Oracle 11g Real Application Clusters (RAC), we see a new process called Oracle High Availability Services or OHAS for short.

OHAS is implemented via a new daemon process which is called ohasd on the OS layer, and the 11g documentation notes that this Oracle High Availability Services Daemon (OHASD) anchors the lower part of the Oracle Clusterware stack, which consists of processes that facilitate cluster operations in RAC databases.  This includes the GPNPD, GIPC, MDNS and GNS background processes.

It appears that RAC DBA's will continue to use the traditional crsctl commands for cluster management and that there are no direct commands for Oracle High Availability Services.

The 11g docs note the jobs of the OHAS Oracle High Availability Services Stack:

The list in this section describes the processes that comprise the Oracle High Availability Services stack.

  • Grid Plug and Play (GPNPD): GPNPD provides access to the Grid Plug and Play profile, and coordinates updates to the profile among the nodes of the cluster to ensure that all of the nodes node have the most recent profile.

  • Grid Interprocess Communication (GIPC): A helper daemon for the communications infrastructure. Currently has no functionality; to be activated in a later release.

  • Multicast Domain Name Service (mDNS): Allows DNS requests. The mDNS process is a background process on Linux and UNIX, and a service on Windows.

  • Oracle Grid Naming Service (GNS): A gateway between the cluster mDNS and external DNS servers. The gnsd process performs name resolution within the cluster.

Enabling Oracle High Availability Services (OHAS) in 11gr2 and beyond

To enable OHAS for each RAC node, you issue the crsctl enable crs command, and this will cause OHAS to autostart when each node re-boots.  To verify that OHAS is running, check for the CRS-4123 message in your alert log:

CRS-4123: Oracle High Availability Services has been started.
ohasd is starting

 

If you like Oracle tuning, you may enjoy my new book "Oracle Tuning: The Definitive Reference", over 900 pages of BC's favorite tuning tips & scripts. 

You can buy it direct from the publisher for 30%-off and get instant access to the code depot of Oracle tuning scripts.



 

 

  
 

 
 
 
 
 

 
 
 
 
 
 
Oracle training Excel
 
Oracle performance tuning software 
 

 

Burleson is the American Team

Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications.

Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:  and include the URL for the page.


                    









Burleson Consulting

The Oracle of Database Support

Oracle Performance Tuning

Remote DBA Services


 

Copyright ? 1996 -  2014

All rights reserved by Burleson

Oracle ? is the registered trademark of Oracle Corporation.