One of the most prevalent trends in IT today is server consolidation. Companies
consolidate mainly to end server sprawl, reduce total cost of ownership (TCO),
increase hardware utilization, and streamline IT resources. But many organizations
aren't seeing these benefits. Their different departments and branch offices
continually acquire software solutions, which tend to come bundled with server
hardware. As these single-purpose servers accumulate, they increase the organizations'
operating costs both in terms of direct hardware purchases and maintenance.
In addition to costs, these accumulated servers also increase infrastructure
requirements with their power, cooling, and networking demands. Not surprisingly—considering
the massive increases in the computing power of today's multicore servers—these
single-purpose systems tend to have utilization rates under 20 percent. More
systems mean greater management efforts and reduced efficiency and flexibility.
One well-known management adage sums up this situation: "Every penny spent on
hardware requires a dollar to manage." Whether your organization will benefit
from consolidation depends on the type of server system you have. Before you
jump on the server-consolidation bandwagon, make sure your system is a good
candidate for this popular solution.
By definition, server consolidation utilizes a shared hardware environment,
and excessive system requirements by one or more of the servers involved will
reduce the responsiveness of all of the servers on the platform. Workloads that
are best suited for server consolidation have low levels of both CPU and disk
resource utilization with occasional spikes of activity where the utilization
rate could approach 100 percent for short periods of time. Combining several
of these low-level workloads can be advantageous, because they don't tend to
overload the target server. When combined together, they can increase server-utilization
rates while still maintaining acceptable service levels.
Relational database servers like SQL
Server don't always fit into this mold. SQL
Server systems often support multiple databases and must concurrently process multiple complex queries—requiring sustained
high levels of CPU and memory utilization
as well as high I/O requirements. In addition, because many of the applications supported by SQL Server databases are mission
critical, the system must also provide high
levels of responsiveness, which isn't well
suited for server consolidation.
While it's true that many SQL Server
installations have the high-system requirements that would cause them to play poorly
in a server-consolidation environment, not
all SQL Server systems are like that. Many
SQL Server systems, especially small departmental and branch-office database servers,
have modest requirements.
In the end, it all boils down to the characteristics of your system's workload.
Workloads with sustained rates of high resource utilization either CPU or I/O
aren't good candidates for consolidation. There are many products available
like Microsoft Operations Manager (MOM), other third-party performance tools,
and even just plain, old Performance Monitor that help you understand your SQL
Server system's workload characteristics. Once you learn your system's workload
characteristics, you'll know if server consolidation is right for your organization.