Posts Tagged ‘HA’
I found a very good article written by Tom Deaderick called “10 Places You Don’t Want a Data Center.” Tom is a Director at OnePartner LLC, which provides high-availability colocation services from the company’s data center in the southwest corner of Virginia. Anyone who is on a site-selection team for a new data center or evaluating new colocation providers should read Tom’s article. OnePartner is doing something right. The company reports having no outages in over 1400 days.
Tom’s #2 place you don’t want a data center is “in a location that suffers from frequent natural disasters.” He includes some useful data on the annual frequency of tornadoes for each state in the United States. Based on a quick glance at the data, you might think you should never build a data center in Texas. The state had an average of 139 tornadoes per year between 1950 and 2004. That’s over 7,600 tornadoes in 55 years. Maryland, on the other hand, had only 6 tornadoes per year over the same period. From a tornado-risk perspective, Maryland is obviously much safer, right? Wrong.
You’ve got to be careful with statistics. Texas, as most Americans know, is the second largest state in the U.S., with an area of almost 270,000 square miles. Maryland is #42 and covers only 10,455 square miles. So if you calculate the tornado-rate per square mile, Maryland ranks 8th in annual tornado frequency at 5.74 tornadoes per 10,000 square miles, 10% higher than in Texas, which ranks 11th. For the record, Florida is the state with the highest tornadoes-per-10,000 square-miles rate at 9.37.
Tom offers 10 important factors to consider when locating a data center. Read the article to get the list, because I don’t want to steal his thunder. But, yes, companies should know the frequency of various types of disasters and obviously avoid known flood plains, airplane take-off and landing paths, and the San Andreas Fault. I wonder if Tom looked at earthquake risk in Virginia. Based on data from the last century, they are extremely rare. But, in fact, a significant earthquake occurred in Virginia in August, 2011. And there was another, less-severe earthquake in the same area just a few days ago. The epicenters for both the August 2011 earthquake and the July 2012 earthquake were almost 350 miles from Tom’s data center. But a much stronger earthquake occurred in southwest Virginia in 1774. I wonder when southwest Virginia will have its next big earthquake. Despite new earthquake prediction techniques, nobody really knows.
That brings me to my last point. Disasters are, by their nature, simple to track, but very difficult to predict. In designing data centers for maximum up-time and minimal data loss, it’s important to protect your data against disasters that you can’t predict.
If you don’t have both a High Availability site locally and a replicated site for system maintenance and disaster recovery some distance away, would it be best to have just the HA site or the replicated disaster recovery site?
With regard to the HA option, Kathleen Lucey, President of Montague Risk Management, and a business continuity management expert pointed out:
If what you are talking about is local clustering in the same site, then I would not consider this to be HA. The protection afforded by a same-site clustering solution is limited to failover to the designated backup server in the event of a failure of the primary. A larger local event could take down the entire cluster, and so this is not really HA, but more properly local hardware backup. Read the rest of this entry »
Today, many vendors use HA and DR almost interchangeably. This is especially evident when they talk of applying the expanding range of virtualisation solutions to improve systems availability.
Tony included a chart of the causes of application failures. It’s no surprise that “user errors” are the most frequently cited cause. Component failures and physical disasters such as brown-outs are near the bottom of the list. Weather or environmental-related disasters such as earthquakes, floods, and fires, and acts of terror or war don’t even make the list. And again, that is not surprising. The article doesn’t talk about the magnitude of the impact of the failure, however. And that is where the analysis needs further explanation. Some disasters can impact the ability of the company to survive. Read the rest of this entry »