1 Reply Latest reply on Jan 31, 2012 7:40 PM by asanga

    Few large nodes or many small nodes

    Sanjaya Balasuriya
      Hi guys,

      In general, what option is better to implement a RAC system; few large nodes or many small nodes?
      Say we have a system with 4 nodes of 4 CPU and a system with 8 nodes of 2 CPU. Will there be a performance difference?

      I understand there won't be a clear cut answer for this. But I'd like to learn from your experiences.

        • 1. Re: Few large nodes or many small nodes

          The worst case in terms of block transfer is 3-way, doesn't matter if you have 100 nodes a single block will be accessed at max in 3 hops. But there are other factors to consider
          example if you're using FC for SAN connectivity I'd assume trying to connect 4 servers could cost more than 2 servers.

          On the load let's say your load is 80 (whatever units) and equally distributed among 4 servers each servers will have 20 (units). If one goes down or shutdown to do a rolling patch then load of that will be distributed among other 3 so these will have 20 + 20/3 = 26.666. Imagine the same scenario if there was only two servers then each will have 40 and if one goes down one server has to carry the entire load. So you have to do some capacity planning interms of cpu to decide if 4 nodes better or 2 nodes better.