Database Reference
In-Depth Information
this virtualized infrastructure, there are lots of advantages over a physical infrastructure
that we can leverage. Even though the resources are shared, it also means we can get
more resources when it's critical.
DBA Behavior in the Virtual World
Let's discuss how the DBA's behavior needs to change and look at a real-life example
of how things are different when your database is virtualized. Every few years, it's time
to buy a new server on which to run your production database. This happens for a
variety of reasons. The most common is the equipment you are running on is getting too
old or the database needs to be on a server with more resources. Bottom line: The
database has outgrown the capacity of the machine, and no matter what you do as a
DBA, it can't keep up.
Management asks you to determine the requirements for the new server on which to
house the database. This is where the games begin. It's pretty simple to look at the
transaction load of the database, extrapolate out some basic growth, and determine a
configuration that will get the job done for four years. As DBAs, that's what we do. But
then we do one more thing: On top of figuring out what we need, we figure out how
much more we think we can get management to purchase. We become like squirrels
getting ready for the winter. We want to gather as many nuts as we can (think of nuts as
CPU, memory, and disk resources) and have them hidden away just in case we need
them. As DBAs, we do this for self-preservation.
The world we have lived in up until this point has been about what we purchase is what
we will have available to us, and we have to make sure it's enough. The problem is that
this behavior, which has worked so well for us over the years, will get us into a lot of
trouble very quickly in a virtualized environment.
The worst thing we can do is oversize those virtual machines that house our databases.
In this shared resource environment, by oversizing the VMs the database sits on, you are
hoarding resources from the other VMs that won't be able to get those resources when
they need them. When VMs cannot get the resources they need, performance is
negatively impacted. It's important that we work with the vSphere administrator,
storage administrator, and network administrator to communicate how much of the
resources we really need and not hoard them. It's also just as important that the team
supporting the virtualized environment provides you the resources you need.
Important
A virtualized database is housed on a shared environment. It's important as
DBAs that we don't hoard resources such as CPU, memory, and disk. Its
important we communicate clearly what the VM that houses the database needs.
It's also important for the vSphere administrator, storage administrator, and
 
 
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