Storage Area Networks For Dummies®

296
Part IV: SAN Management and Troubleshooting
Managing database storage
Another example — much more complicated but still completely
autonomous — proves that people are completely useless after a SAN is
put in operation. (HAL, did you say that, or did I?)
Suppose that your database (XYZ) is getting larger and larger, and it begins
to run out of space one night. At the 99 percent capacity level, automation
can step in, allocate more disk space to your database server, and then tell
the database software to expand to the new storage area. This function keeps
your database administrators (DBAs) from getting paged at 3 a.m. and shows
how flexible your new SAN environment really is. This example is a bit more
involved than the backup example in the preceding section, requiring coordination
with your DBAs to developing the scripts, but it can be done.
Oh, by the way, the SAN framework also makes sure to send you an e-mail to
tell you (when you get in at 10:30 the next morning) that the XYZ database
grabbed a few more gigabytes of space last night . . . and you’re welcome.
As you see, the possibilities can be relatively simple or get quite complicated,
depending on what you need to anticipate and how you go about delivering
the fix for the problem. Compare these two examples with what you’d have to
do today without a SAN in place. Order a disk? Wait for your vendor to install
it and configure it? With a SAN that’s automated, your problem is solved in
about five minutes at 3 a.m. without waking anyone up.
Providing a Service Level Agreement
A Service Level Agreement (SLA) is a contract between your end users and
you. It quantifies a level of performance, reliability, and support that you
promise your users, in essence making them your customers.
With an SLA, you define a set of parameters that you must meet to keep your
customers from yelling at you. As long as the computing environment that
you promised doesn’t go outside the bounds of the SLA that your customers
agreed on, you won’t have to worry about getting a phone call that something
is wrong.
What happens if an SLA is breached? Usually, someone gets angry and starts
calling people to find out what’s going on. Sometimes a monetary penalty is
assessed. Usually, the customer doesn’t have to pay for service during the
outage, just like when your cable television service goes out.