Scott Drummonds on Virtualization

Virtual Machine Guest OS Optimization

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Last week I was visited in Singapore by Veloxum’s VP of marketing, Chris Cicchetti. Chris was in town presenting Veloxum at a local cloud conference. We both had some extra time and decided to get acquainted over a Thai lunch.

Chris explained that Veloxum works by modifying guest and host (hypervisor) parameters to optimize performance. He claimed that huge gains–frequently 30% and more–could be derived from improving guest OS kernel parameters, application parameters, and host advanced settings.  Veloxum constantly monitors and modifies these parameters to suit changing conditions, which they believe will yield continual benefits in a dynamic environment.

In our lunch meeting I contained my skepticism. My long-held belief is that OS and hypervisor out-of-box settings were close to optimal for most workloads. Messing around with these settings is generally a Bad Thing. 90% of the applications work perfectly with default settings.

However, I ultimately changed my mind.

First, I had forgotten the 90-10 rule of performance optimization.  Sure, 90% of applications work perfectly out of the box.  But the other 10% end up consuming 90% of the VI admin’s time.  The trouble for VI admins is figuring out which applications fall into the 10% category and how they can be be optimized. If a tool could identify and optimize the guest and OS for these apps, it would be providing great value to VI admins.

The second thing that changed my mind was the opinion of one of VMware’s performance gurus, Jeff Buell.  Far from being a keyboard monkey, Jeff was one of the quiet, hardworking, and relatively unknown brains at VMware that gave me information to make me look smart publicly.  At my request Jeff skimmed Veloxum’s sole white paper and concluded the paper’s claims of performance improvements could be substantiated. Jeff cited his own experience in playing with transparent page sharing agressiveness as one way host tuning could improve throughput. He reminded me of the HIMP setting as the other.

For years VMware has intentionally stayed away from guest- and application-specific optimizations. The world of guest OS defragmentation is rich in this space with companies like my friends at PerfectDisk. But I’ve not yet seen anyone monitor and modify guest OS settings dynamically. While it would not surprise me if VMware some day moved into guest optimizations, today there is an opportunity for software vendors to capitalize on the gap caused by VMware refusing to do so. Veloxum may be in the right place at the right time.

If any of you are using Veloxum or have evaluated it I would be interested in hearing your thoughts.  I have not used the products or deeply investigated its claims.  But the theory is sound.  I would love to know if any of you can comment on it in practice.

One Response

Hi Scott,

when it comes to guest optimization, i thought in the first place about the slowest element of a computer, which is the disk. After reading this article http://thebackroomtech.com/2008/09/10/perfomance-test-windows-server-2003-r2-partition-alignment-on-an-emc-san/
I thought there must be a way to get block size for every application.
With hiomon it seeams that it is possible to get the I/O profile for every application.
It although possible today to change the cluster size online without reformatting