11-18-09 | Blog Post
I was just describing what N+1 means for a data center to a team of new employees that joined Online Tech this week.
The question came up – is an N+1 data center the best strategy for small & mid-size enterprises?
The answer is “it depends”.
“N” is enough to do the job – enough power, cooling, UPS, or internet bandwidth required to support the servers and applications running in the data center. “N+1” is having 1 more of every component so that if (or should I say “when”) anything fails or needs to be taken offline for repair, there is another component on line to take over for the failed unit.
Frankly, “N+1” is about risk reduction. The “+1” is about eliminating single points of failure in critical systems – including HVAC, UPS, generators, Internet connections, core routers, firewalls, and core switches. This elimination of risk can even extend to high availability (HA) power and network delivery to each server through redundant power runs through separate PDUs and redundant network drops though different switches.
Whether it’s the best strategy depends on the enterprises demand for uptime. Some servers can be shut down if power or cooling is lost, and losing an internet connection for an hour or so, while painful, isn’t critical to the organization’s success. An example of this might be a server that is used for software development. If a failure hits the data center, the sever can be shut down with out impacting customers or critical systems. In this case, where uptime isn’t critical, a non-redundant infrastructure (“N” if you will) can do the job.
Critical systems and customer facing servers on the other hand that require 7x24x365 are typically housed in an N+1 data center. For example medical records that need to be accessed night and day, or Software-as-a-Servce (SaaS) applications delivered over the web require 24x7x365 uptime and online connectivity. In cases where uptime is critical, then an “N+1” data center is a requirement.
Of course, the “+1” in every system requires additional capital to add the additional components to the infrastructure.
One of the most cost effective substitute to expanding one’s own data center to meet N+1 requirements is to host the critical servers (that need 7x24x365 uptime and online connectivity) to a managed data center – through colocation or managed server hosting. Companies like Online Tech have made significant investments to build N+1 through their entire infrastructure that can be cost effectively shared with hundreds of clients.