Craig S. Mullins

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October 2003





The DBA Corner
by Craig S. Mullins  


Round-the-Clock Data Availability is Elusive but Expected

DBAs scramble to address a variety of different needs ranging from the design of new applications to keeping critical applications operational. All the while, business executives are demanding that DBAs accomplish these tasks with minimal or no downtime. As more businesses demand full-time system availability, and as the cost of downtime increases, the time available for optimizing performance on business-critical systems and software is shrinking.

Availability is the holy grail of DBAs. As King Arthur's knights sought the Holy Grail, DBAs seek 100 percent data availability. But it is so elusive.

If the data is not available, the applications cannot run. And if the applications cannot run, the company cannot conduct business. This translates to losing money -- and we all know what happens when your company does too much of that. Therefore, the DBA is responsible to do everything in his or her power to ensure that databases are kept on line and operational. Now, as we've discussed in past columns, PAR (Performance, Administration, and Recovery) defines the basic role of the DBA (see But PAR must be performed within the context of assuring data availability. This requires more automation, more advanced technology, and more planning.

In the olden days, there was such a thing as a batch window. The on-line databases were taken down at a predetermined time and only batch programs could access the data. But the age of the batch window is over. Exacerbating the trend toward never-ending availability is e-business. Coupling databases to the Internet dramatically changes the way we do business. The expectation is that the business, and hence its data, will be more connected, more flexible, and importantly, more available. When you integrate the Web with database management, heightened expectations are placed on DBAs to keep databases up and running more smoothly and for longer periods of time. An e-business must be available and operational 24 hours a day, 7 days a week, 365 days a year. If your customer is conducting business at 3 AM in Kuala Lumpur, you had better be, too.

Some pundits use the phrase "Internet time" to describe the rapid rate of change and the rapid development schedules associated with Internet projects. But the DBA can think of Internet time as a simple Boolean equation--there is uptime and there is downtime. During uptime, business is conducted and customers are serviced. During downtime, business is halted, and customers are not serviced. So Internet-age DBAs are sharply focused on maintaining availability. Of course, e-business is not the only driver for increased availability. Other factors include:

  • The "fast food" mentality of customers who demand excellent service -- "now!"
  • Airline magazine syndrome--when your manager reads an article from the in-flight magazine during his latest junket that states how a competitor offers round-the-clock service, so your next project has to offer round-the-clock service, too.
  • The desire to gain a competitive advantage in the marketplace by offering superior services at a time of the customer's choosing.
  • The need to react to competitors who offer better service to customers.

In this environment, DBAs are tasked with tracking down and eliminating anything that conspires to reduce data availability. Of course, you could increase your budget to purchase better DBA tools and redundant systems. But that would make too much sense! So DBAs struggle against all odds to grab that holy grail, and it frequently seems to be just beyond their grasp.

From Database Trends and Applications, October 2003.

2003 Craig S. Mullins,  All rights reserved.