January 30, 2018

Virtual Paranoia?

Lately I’ve been seeing what I think might be an interesting yet disturbing new trend: whenever there’s a problem that initially seems unusual and/or unexplainable, it’s not uncommon to quickly question virtualization as a potential source of the issue. I fully understand that virtualization adds a new variable to the basic equation – and represents greater complexity due to more moving parts. But it seems to be somewhat rushed to the head of the list. In some respects it reminds me of the days when many tech support calls started off with how much memory do you have, oh just that much, that’s your problem.

Now that’s not to say that virtualization is without some additional concerns that must be added to the mix – some of which can radically affect the results. But as far as true issues that virtualization breaks – I’ve run into just two so far. Some client operating system and database monitoring tools are very sensitive to the real time clock, and any skew between the host and client VM may yield slight variations that might possibly affect some results. And second, some older Windows versions have poorer memory management that seems not to work 100% reliably on VM’s. Shy of these, I’ve yet to encounter any problems that I can point the finger to the virtual machine software (e.g. VMware).

So when someone says “I can’t explain problem X and it doesn’t occur on non virtualized machine that’s setup exactly the same”, please make sure only to accept such arguments with a fair and reasonable amount of verification. Let’s not waste any precious resources and cycles chasing such an easy scapegoat. There may be issues where virtualization is legitimately the culprit – just not most of the time. So let’s not promote it from obscurity to the head of the class.

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About bscalzo2

Bert Scalzo is an Oracle ACE, blogger, author, speaker and database technology consultant. His work experience includes stints as product manager for DBArtisan and Rapid SQL at IDERA and chief architect for the popular Toad family of products at Quest Software. He has three decades of Oracle® database experience and previously worked for both Oracle Education and Oracle Consulting. Bert holds several Oracle Masters certifications and his academic credentials include a BS, MS and Ph.D. in computer science, as well as an MBA. He has presented at numerous Oracle conferences and user groups, including OOW, ODTUG, IOUG, OAUG, RMOUG and many others. Bert’s areas of interest include data modeling, database benchmarking, database tuning and optimization, "star schema" data warehouses, Linux® and VMware®. He has written for Oracle Technology Network (OTN), Oracle Magazine, Oracle Informant, PC Week (eWeek), Dell Power Solutions Magazine, The LINUX Journal, LINUX.com, Oracle FAQ and Toad World. Bert has also written the following books: • Oracle DBA Guide to Data Warehousing and Star Schemas • TOAD Handbook (1st Edition) • TOAD Handbook (2nd Edition) • TOAD Pocket Reference (2nd Edition) • Database Benchmarking: Practical Methods for Oracle & SQL Server • Advanced Oracle Utilities: The Definitive Reference • Oracle on VMware: Expert Tips for Database Virtualization • Introduction to Oracle: Basic Skills for Any Oracle User • Introduction to SQL Server: Basic Skills for Any SQL Server User • Toad Unleashed • Leveraging Oracle Database 12cR2 Testing Tools • Database Benchmarking and Stress Testing (coming 2018)

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