Could you please tell me the about the High Availability and Advanced Availability functionality of CA Service Desk 14.1. What are the differences between these terms.
I will preface this by saying that the concept of "High Availability" is not a CA coined term and is not specific to CA's products. Its a general term within the industry. When folks in the industry mention the concept of "High Availability" - 99% of the time they are referring to a microsoft clustering setup, OR something similar, meaning an application is running across multiple server nodes, and so if one node goes down, the end users are not affected. This concept can be applied to any application. Now, as for Advanced Availability, this is a concept that IS a CA coined concept and is specific to the Service Desk application. Advanced Availability is a set of functionality within the product that allows for the application to be distributed across multiple servers (distributing the user load), and allows for a bit more fault-tolerance than what we call "Conventional" architecture. For many years, Service Desk has had the capability to use what we call a Conventional Architecture which consists of a Primary Server, and one or more Secondary Servers. This allows for the user load to be distributed across multiple secondary servers, leaving the Primary Server to be used specifically for processing data and transnational things like events etc, without having user sessions using up its resources. In a conventional architecture however, the secondary servers are nearly 100% dependent on the primary server being up and running. If a primary goes down, the secondary servers stop functioning, and thus there is an outage at the user level. Advanced Availability is similar, in that it distributes the user load across multiple servers, however there are some differences which allow the administrator to intervene in certain circumstances to minimize the effects of an outage. An Advanced Availability architecture consists of what is called a Background Server, at least one Standby Server, and one or more Application Servers. Architecturally, the main difference with Advanced Availability vs. Conventional is that in Advanced Availability there are some daemons (processes) that run on each of the application servers such as the bpvirtdb daemon which reads and writes data from/to the database, where as in Conventional architecture, the bpvirtdb process only runs on the primary server and not the secondary servers. This allows for better performance by having less load on the background server. The standby server is used as a failover server for the background. An admin can run a command to failover from the background to the standby to do maintenance on the original background server. They can then fail back to the original background server, and do the same maintenance on the standby server. Similar actions can be taken on application servers by using a command to do what we call "Quiesce" a server - which notifies the users on that app server that they have X number of minutes (set by the admin in the command syntax) to save their work and log off of that server. The users then log back into the application, but since that server was quiesced, it will no longer handle any users sessions until its brought back up. Those users that log back in would be logging into a different server. That application server can then be worked on by the admin and then brought back up. So this whole scenario allows for what we call "rolling maintenance" where you can apply fixes, or do server maintenance with minimal effects on the users. Now keep in mind that when we say "failover" it is not an automatic process. It requires human intervention. One last note on the term Clustering - Service Desk Manager is cluster tolerant, but not cluster aware. By this we mean that the application will tolerate being installed in a cluster environment, and will operate properly, however, it is not aware that it is in a cluster and thus it has no ability to failover automatically OR gracefully handle any type of failover without manual intervention such as restarting services upon a cluster failover.
So in summary, Advanced Availability allows for a better distribution of user load, as well as functionality to allow admins to minimize outages to much smaller groups of users rather than all users at the same time.
I hope this helps clarify a bit.
Have a great day!
Great explanation Jon. Thank you .
Sippy, our support team presented some information about AA to the Community members earlier this year/last year -> https://communities.ca.com/videos/1124
Maybe that helps too?
Thanks Jon for above explanation
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