Overcoming the Challenges of Managing Databases in Virtual Environments

There is no doubt that virtualization is radically changing the shape of IT infrastructure, transforming the way applications are deployed and services delivered.  Databases are among the last of the tier 1 applications to be hosted on virtual servers, but the past year has seen a huge wave of increase for production Oracle, SQL Server and other databases on VMware platforms.  For all the benefits of virtualization, including cost-effectiveness, there are some impacts on the IT staff involved. Unfortunately for the DBAs virtualization often means losing control and visibility of their systems, which can ultimately hinder their ability to deliver database-oriented business solutions.  While in the past, DBAs had perfect visibility to the physical servers hosting the databases, the virtualization layers and the tools to manage them are typically out of bounds to them.  While all the excitement of late has centered on VMware and other virtual machine systems, the DBAs have a valid reason for skepticism.

Invisible Layers

The problem stems from the fact that databases see only what happens within their individual virtual server, and when the DBA looks at key statistics like CPU, memory or I/O utilization, the statistics revealed are artificial, created by the virtual machine to simulate an actual server.  If the database monitoring tool says it is using 50% of CPU, the DBA must wonder, "Is that really accurate, or is there a larger pool of CPU resource actually available at the physical host level ready to be allocated?"   With a conventional database monitor in a virtualization environment, which cannot tell the difference between a physical and virtual server, the DBA will never know whether key statistics are accurate.  The underlying physical layers of actual memory, network, CPU and storage access are invisible to the DBA.  Only the VMware administrators, with their specialized virtual system managers, can see what is really happening. 

 No VM Tool Access

So what's the big deal?  Just connect to vCenter, or similar virtual layer management utilities and get the real picture.  Not so easy.  vCenter, the VMware management system, is both complex and secure. Within most IT organizations, only the VMware administrators have access and the knowledge to use the wealth of performance and availability information.  Just as the DBAs have their own monitoring tools to control their databases, arcane and invisible to other groups, the DBAs generally do not have access to the VMware infrastructure management tools. 

The stakes are high for the DBA however.  If changing virtual server resources or a new vm on the host server cause a database slowdown, the DBA is the one responsible.  Application performance is still directly tied to database output, and application owners will point to the DBA when there is a problem.

Crossing the IT Boundaries

What is required is a method for DBAs to gather just what they need from the virtual and physical host layers, without interfering with the VMware operations.  And just as importantly, when problems arise in the database that are potentially related to virtual system resources, they need a way to communicate the issues with the VMware administrators and other IT groups in a manner that can be commonly understood. 

Virtualization Aware Database Tools

A new category of tools are addressing this need, crossing the boundary between the DBA and the virtual system manager.  The key is to give the DBA visibility in a non-intrusive way and expose just enough information so that a DBA can do his or her job in the new virtual environment.  Without getting mired in virtual details, a "virtualization-aware" tool can correlate the essential virtual statistics with the database operating data to give a true picture of the operating environment.  For example, if a virtual CPU is dynamically moved away by VMware, the DBA can have some insight to what has really happened and why database performance has suddenly changed.

The virtualization storm is raging, and there is no stopping it now. DBAs can ignore it, but only with perilous consequences to them and their database performance. Or they can find a way to join the party and make the best of it.  Finding tools that connect DBA processes to colleagues across the IT organization, and linking the database operations to those of the virtual infrastructure layers, are key steps for DBAs.