Is it mandatory to have at least 3 nodes part of the Data repository ? I see the sizing tool does not allow anything less than 3 . I understand there are certain advantages of a 3 node cluster instead of a single node DR but in certain scenarios the resource requirements (CPU, Memory, Disk) for a 3 node cluster are quite enormous and if we decide to go with a single node would there be any issues ?
Are there any customers who are running CA PM in a single node or does everyone choose to go with a multi node cluster for DR?
Please let me know your thoughts
all the time we have had customers running with single node DR/Vertica system, especially in smaller scale environments as described here Install a Low-Scale System - CA Performance Management - 3.5 - CA Technologies Documentation
The sizer reflects this option as well when scaling e.g. a system with less than 150.000 polled items ( e.g. 3.500 devices).
For larger environments we recommend 3 node (or even more) clusters, which not only tolerate single node failures but also provide distribution of query load.
Thanks for your comments, the number we are looking for is way above 3500 device limit so may be we should consider a 3 node cluster . I agree there are surely advantages of having a 3 node cluster for a large environment, but resource requirements provided by the sizing tool looks enormous when considering the CPU, Memory and Disk ( data+backup) compared to what we have been using for eHealth.
Anyways we will consider our resource availability and make a choice
Just wanted to see if you had any other questions regarding the Vertica configuration after Lutz's response. As for the sizing in comparison to eHealth there is definitely a substantial difference when considering the DR component in particular. It is this sort of requirement that allows the k-safe functionality and adds the extra redundancy that keeps you up and running if a node goes down.