Pick backup temperature that fits computing needs
POSTED: Saturday, May 30, 2009
Since the advent of computing, the question has always been asked: "What are you going to do if the system goes down?"
While most everyone is familiar with the concept of employing a backup system, there are varying methods of implementation. Depending upon the chosen method, there are often unforeseen ramifications.
There are basically three techniques of implementing a backup system. These are affectionately referred to as hot, warm and cold. The temperature ratings theoretically correlate to the state of the system, although IT folks will tell you that computers like to be cold.
A hot backup (or standby) runs at all times in conjunction with and parallel to the main or production system. It is virtually identical to the production system in terms of hardware and software configuration and operation. The hot backup contains data that is reasonably current, and switch-over to the hot backup is done very quickly.
Like a hot standby system, a warm backup is operational at all times. A warm backup is not necessarily identical to the production system, but is capable of running all necessary software. Such a system typically takes longer to bring online than a hot backup and usually requires a data update.
A cold backup is merely hardware that is configured to be able to run the production system software but is not running. Cold backups typically require data and sometimes application updates before becoming usable.
In terms of cost and complexity, hot backups are the most difficult to engineer and the most expensive. Cold backup systems are the cheapest and easiest to deal with.
Like anything else, organizations should choose their backup solutions according to their business requirements.
A major ramification that is often overlooked, however, is the issue of software licenses. One might think that since only one copy of the software is running at any one time, then only one license needs to be purchased. This is not always true!
Typically for cold backups, software vendors will agree to a single license.
Software vendors are much less agreeable to a single license for warm backups and almost always require some sort of license for a hot standby. This might not be a full-price license, but there are relatively significant costs nonetheless. Many software vendors have special versions of their packages built specifically for use in a hot backup setting. Again, while these versions might not be twice the cost, the additional expense will be relatively significant.