Tuesday 25 October 2016

Exploring hyper-converged without the hype

Hyper-converged solutions from a number of vendors (new and old) have grabbed the headlines and become popular with organisations which need a simple, small footprint package including hypervisor, compute, networking and storage which can scale-out to meet their needs. This architecture is being touted as the "software defined" future of the data centre which can eliminate IT silos and fit into any size of organisation.
By using software to both glue the components together and to provide a simple management interface, these systems can be deployed quickly and are space efficient with a low management overhead.

Hyper-converged infrastructure (or HCI) also has the advantage that all the hardware components are housed in a standard X86 server chassis (often with more than one server "node" per box) which makes it high density and low cost.


Watch this short video to see how HCI compares to traditional and converged solutions.



 However, there are a few limitations to watch out for:

  1. You cannot grow storage capacity without investing in compute too (which you may not need). 
  2. Performance will be restricted by the network connecting the system nodes – the more you add, the greater the inefficiencies.
  3. The virtual San within the solution can only be accessed by virtual machines. So any non-virtualised database applications may not be able to use the storage. Note some solutions may allow an iSCSI connection to the virtual SAN, but may not provide the low latency and performance needed.
  4. Although it uses relatively cheap hardware, the software to run the solution is not. Experience shows that in larger systems, traditional or converged solutions may be lower cost.
  5. Although designed to eliminate silos by providing a single scalable infrastructure, hyper converged can become its own silo when it cannot meet the requirements for all applications.
  6. Database applications are usually licenced by the processor cores that they "touch". In a hyper-converged solution, this could be the entire cluster meaning high cost or breaches of licence agreements as nodes are added. 
Some other considerations:
  • It's worth checking out a number of vendors as there are differences between them and specifications are also evolving very fast.
  • Consider whether you want an appliance type solution or a software only approach (meaning you can build your own solution).
  • Think about your hypervisor choice and how that fits with the rest of your estate. You will probably want to be able to migrate virtual machines across datacentres and maybe out to the cloud. So don't let the hypervisor choice stand in the way of this.
So in summary, hyper-converged or HCI can bring huge benefits in terms of flexibility, operational costs and the speed of deploying new applications, however there are some limitations which need to be understood. In other words, go in with your eyes wide open.