Executive Summary:
Virtualization--running Microsoft SQL Server database environments under virtual machines (VMs) is a popular, if not somewhat controversial--topic on www.sqlmag.com. SQL Server Magazine readers share their opinions about the benefits and feasibility of server consolidation using VMs and the benefits and risks of running SQL Server production environments on VMs.

Get Active Online at Sqlmag.com!
Would you trust running your production SQL Server databases under a VM? Let us know—and find out what your peers are saying about SQL Server virtualization—at www.sqlmag.com, InstantDoc IDs 97439, 95799, 97215, and 97289.

Server consolidation is an obvious benefit of running applications in virtual machines (VMs). But running SQL Server in production on a VM is still somewhat controversial among database professionals, in part because of DBAs’ perception that virtualization products can’t adequately handle the disk I/O–intensive nature of SQL Server applications. Several December 2007 articles explored this topic, and readers responded by weighing in on the virtualization question.

First, in response to Michael Otey’s editorial in the December 2007 issue of SQL Server Magazine (see “VMs vs. Multiple SQL Server Instances,” InstantDoc ID 97439), PNovelli commented, “This \[article\] was very timely as we build out a QA environment. QA instances of our various production servers \[are\] attractive compared to the VM route we’re going. However, I'm wondering if there are any limitations or differences in how linked servers behave between instances.” And katesl@earthlink.net brought up a possible limitation of VMs on SQL Server. “On a VM, SQL Server has access to one processor only, so parallel query execution no longer exists. That isn’t SQL Server for large databases.” Reader dwknapp suggested that it would have been useful to include in the article comparisons of VM software products--presumably related to SQL Server’s performance running in a VM.

Virtualization Uncertainty


“Running SQL Server in a Virtual Server Environment,” InstantDoc ID 95799 sparked a dialog with some readers who are still dubious about the benefits and feasibility of handing over their production SQL Server environments to VMs. “I'm not seeing a good reason to run a VM,” said Wavel. “We are a very small company—every server we buy affects our bottom line… \[we can’t\] buy as much hardware as we desire…. I'm looking for the one big reason that makes me slap my head and say ‘Duh!’”

An expert panel discussion at PASS 2007 last September on SQL Server and virtualization drew a large audience, so it’s clear that database pros are paying attention to the virtualization trend. (See “2007 PASS Community Summit: Event Wrap Up,” October 2007, InstantDoc ID 97215.) The experts hesitated to recommend running production servers on VMs, but about half the audience said they were doing just that. And in their article about SQL Server trends in the December 2007 issue (see “SQL Server Trends in 2008,” InstantDoc ID 97289, editors Megan Bearly and Jeff James point to evidence that virtualization is gaining momentum at SQL Server sites. Check out their predictions and tell us whether you agree!


--Anne Grubb, Web site strategic editor, SQL Server Magazine