We seem to be getting many requests for information on our RAP and the link to the IBM HA on a Shoestring presentation which has made the rounds at Common a number of times. We produced a white paper many years ago which was the starting point for the technology, it only showed how we took a journal receiver from a remote journal and applied it to the database which was attached to a local journal but it did show what was possible. As you can see from the presentation we did work very closely with Larry in making the technology work, Larry was an inspiration and was madly committed to the Journal Technology, we do miss him a lot!
RAP has changed significantly since those first discussions with Larry Yougren, but the basic concepts are still the same. We have listed the presentation in the Downloads section of the Blog for those of you who didn’t get a copy from attending an IBM session but want to understand the principles.
If you want to create your own HA on a Shoestring program the advice given in the presentation is a good base to start from. We had to make significant changes to the processing due to the APYCHGJRN and APYCHGJRNX incompatabilities and have added many features which make the product much more user friendly and probably closer to true HA than the HA on a Shoestring will ever get.
A couple of things to remember if you are going down this path
1. The APYCHGJRNX command is required if you want to support DDL entries (File creates). However it does have some features missing which only APYCHGJRN provides. You cannot run the two commands against the same receiver in a two pass process! V6R1 removes the differences so if you have V6R1 it will be a lot simpler. The other option is to use the QDBRPLAY API to get over the APYCHGJRN functional deficiencies.
2. Data Area and Data Queue’s have no creation support built in and manual processes to build them and apply the changes on the fly don’t work! You will have to come up with an alternative option if this is required.
3. The HA on a Shoestring programs do not cover error reporting in any depth, you will also need to create management functions for the journals on both systems.
4. Auditing is not provided nor is any switch management so be prepared to build those as well.
5. There are a few gotcha’s which are not made clear in the presentations. Read the Journal manuals closely….
I did know where the IBM source was for the programs but cannot find it to add to this post. If I do find it I will post it for anyone who is interested.
If you get stuck don’t expect us to help, we are only making the presentation available for those of you who have the skills to take this further… If you want to trial RAP you are free do do so.