Single versus redundant servers

By 21st June 2013September 16th, 2015No Comments

When deploying a solution, there is always the option of choosing between a single "large" server, or two "smaller" servers. The single "large" server usually works out a little more expensive (because of the hardware density and technology) - but there also some positives in doing this.

We cannot decide which is best suited for your needs, so here are the pro's and con's of each so that you can make your own decision.

  Benefits Downsides
Single Server Substantially faster communication between web and database nodes No hardware failure redundancy
  Pooled resources provide more effective resource utilisation No isolation of frontend/backend, so admin traffic could influence frontend performance
    Usually more expensive than two smaller systems
    Longer lead times to deployment
Dual Server Highly available, can survive the failure of a single server without loss of service Twice the risk of hardware failure
  More control over traffic distribution (eg. dedicated backend/admin server) Bottlenecked resource over network connection
  Usually less expensive than a single large system Slower disk writes due to replication
    Twice the server management administration
    Horizontal scaling would usually require more hardware (due to smaller machines)
    Scaling vertically from 2 machines to a single larger machine is time consuming