A recent effort to virtual servers has led to most organizations to visualize some or all of their SQL Server instances. The effort to virtualize SQL Server database instances has also led to issues that had to be resolved to address deployment and performance issues. In this article by Alan Sugano, we read about how he has adapted his procedures for this effort.
Most SQL Server installations don’t use 100 percent of a server’s resources all the time. In fact, many SQL Server applications use only a percentage of a server’s processing potential. SQL Server processor utilization tends to be high for short periods of time. The current version of servers that are available with quad-core processors and significantly faster Serial Attached SCSI (SAS) drives capable of 3Gbps transfer rates represent a quantum leap in server performance. Virtualization can take advantage of the processing power of this new generation of servers, providing significant leverage for your hardware dollar.
Physical server advantages. Traditionally, SQL Servers run on dedicated hardware. This gives the server full access to all the processing power on the server. Running SQL Server on a physical server means that the server doesn’t need to compete with other virtual servers for resources, and a physical server will perform approximately 10 percent to 25 percent faster than a virtualized server on the same hardware. SQL Server 2005 Standard and Enterprise versions can address the maximum amount of memory that the server and OS will support. Also, a hardware failure on the server will affect only one SQL Server installation.
Physical server disadvantages. A physical server can waste resources because the server’s processing power often goes unused. Using one physical server per SQL Server installation significantly increases your hardware costs, and if each physical server is placed on a service contract, your maintenance costs are also higher. And the greater number of physical servers consumes more electricity and requires more physical space than a virtual server setup does.
Virtual server advantages. By consolidating several virtual server guests onto a single physical server, you can save a significant amount of hardware cost and provide better utilization of hardware resources. When determining where a virtual guest should reside, pick a physical server that hosts complementary guests. For example, if a SQL Server installation will place a significant amount of I/O stress on the processor, run it on a physical server that hosts other virtual guests that don’t require the same type of I/O processing.
Virtual servers can lower your hardware maintenance costs because you’ll have fewer physical servers to maintain, as well as lower electric bills and power requirements. With the cost savings, you might be able to place all your host servers on a 24×7 support contract compared with a 8×5 support contract if you’re not using virtual servers. Even with this increased service level, you’ll likely have a net savings for hardware maintenance. Virtual servers also make bare metal restores easier. Every virtual server hardware configuration is consistent regardless of the host’s physical hardware configuration. Therefore, you simply copy the virtual server guest files to another physical host.