Data Availability is Elusive but Expected
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 www.dbta.com/columnists/craig_mullins/dba_corner_0902.html).
But PAR must be performed within the context of
assuring data availability. This requires more
automation, more advanced technology, and more
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,
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:
"fast food" mentality of customers who
demand excellent service -- "now!"
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.
desire to gain a competitive advantage in the
marketplace by offering superior services at a
time of the customer's choosing.
need to react to competitors who offer better
service to customers.
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.