IT managers use two terms when talking about systems availability. These are: High Availability or “HA”, for keeping systems running without any form of unplanned down time; and Disaster Recovery or “DR”, for ensuring that systems are rapidly returned to operation if they fail. Some confusion has developed between these terms …

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Tuesday 9th November 2010 12:03 GMT jake

HA & DR?

From my perspective, it's online (local memory ... fast ... a workstation), nearline (available over the network, without human intervention ... sometimes slowish ... "the web") & offline (tape that isn't physically available to the Memorex robot and needs human intervention ... "the cloud") ... but then I come from a real hardware background.

In other news ... March of 2008? Is freeformdynamics getting further & further behind? Perhaps they should get their heads out of the Clouds and invest in online storage ...

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Tuesday 9th November 2010 12:03 GMT Steve X

Some confusion has developed between these terms over the years.

True, and this article isn't helping.

Traditionally High Availability (HA) has meant the same as it does today, ensuring that a localised fault such as a server or network outage, or a disk crash, is automatically handled in such a way that a service remains available, or is restored very rapidly.

Disaster Recovery (DR), as the name implies, is a solution to a more widespread outage, perhaps a fire or a flood, which takes a whole datacentre off-air. It may not be automated, and recovery times are often somewhat longer, especially when it is integrated as part of a general Business Continuity plan which covers more than just the IT aspects of a disaster.

I would say that there is much more confusion between the terms Fault Tolerant (FT) and Highly Available (HA), which may be what this article is really considering.

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Tuesday 9th November 2010 13:35 GMT Anonymous Coward

tx

Well, I quite liked the article, don't care so much about whether it's HA or DR as long as it's UP...

Having been partially DOWN myself recently, I think this is a very important topic.... I especially like the idea of a "business service catalogue" which details costs/benefits of HA solutions, for a particular input.

I also like the idea of a root cause log, not mentioned in the article but implied by the very nice bar chart. I plan on implementing both as database tables in my BIS.

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