Scott Drummonds on Virtualization

Solid State Disks and Host Swapping


Recently I have been thinking, talking, and writing about ESX host memory swapping a lot.  ESX swaps memory under the same conditions that traditional operating systems do; the application(s) is using more memory than available on the physical hardware.  Host swapping is an unavoidable consequence of this condition, whether virtualization is present or not.

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Your Performance Enemy: Host Swapping

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Three times in the past week I have engaged in challenging discussions on host memory swapping and its impact to performance.  If you read my article on host swapping and the whitepaper it summarized, you know the deleterious effect on performance caused by host swapping.  When reading the paper, one of our most astute customers saw a sentence that gave him pause:
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ESX Memory Management: Ballooning Rules


[Taken from my communities blog, this article shows you why you should “Love Your Balloon Driver”.]

Earlier this month we finally published one of my favorite papers from ongoing vSphere launch activities. This paper on ESX memory management, written by Fei Guo of performance engineering, has three graphs that are absolute gems. They show balloon driver memory savings next to throughput numbers for three common benchmarks. The conclusion is inescapable: the balloon driver reclaims memory from over-provisioned VMs with virtually no impact to performance. This is true on every workload save one: Java.
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Newer Processors and Virtualization Performance


[New content has been added to this is an update to an old article from the performance community.]

Newer processors are much more important to virtualized environments than the non-virtualized counterpart. Generational improvements have not just increased the raw compute power, they have also reduced virtualization overheads. This blog entry will describe three key changes that have particularly impacted virtual performance.

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