by Craig S. Mullins
One of the on-
But the business need for around-
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. Of course, e-
Although the push to improve availability continues unabated, a valid question that remains is "just how much availability is enough?" Just because you can provide 24x7 availability does not mean you always should. There is a cost associated with diminishing downtime and this must be assessed in terms of the business requirements and budget before attempting to always deliver additional uptime. Yes, DBAs can take measures to design databases and build systems that are created to achieve high availability. But the DBA must negotiate with the end users and clearly explain the costs associated with a highly available system.
Be that as it may, the demand for higher availability, especially for e-
Downtime and outages are the enemy of availability. There are two general causes of application downtime: planned outage and unplanned outage. Historically, unplanned outages comprised the bulk of application downtime. These outages were the result of disasters, operating system crashes, and hardware failures. This is simply not the case in today’s IT environment. Instead most outages are planned, caused by the need to apply system maintenance or make changes to the application, database, or software components. Studies show that approximately 70 per cent of application downtime is caused by planned outages to the system; only 30 per cent is due to unplanned outages.
What does all of this mean for the DBA? Although it is important to plan for recovery from unplanned outages, it is even more important to minimize downtime resulting from planned outages. This is so because planned outages occur more frequently and therefore can have a greater impact on availability than unplanned outages.
How can DBAs reduce downtime associated with planned outages? The best way to reduce downtime is to avoid it. Consider the following technology and software to avoid the downtime traditionally associated with planned outages:
These are just a few of the techniques that can be used to minimize database downtime. The primary thrust of these techniques is to enable database maintenance tasks to be performed while the data remains online and operationally available to applications.
As databases grow in size and complexity, so, too, do the chances that bad transactions will corrupt the data on which your business depends. A prepared DBA group will have an arsenal of techniques, tools, and procedures at its disposal to minimize or eliminate database downtime.
From Database Trends and Applications, March 2011.
© 2012 Craig S. Mullins,