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Database Performance Myths

There are a few common myths about virtualizing databases:

* Databases have a high overhead when virtualized: Virtualized Databases can perform at or near the speed of physical systems, in terms of latency and throughput. The virtualization overhead for typical real-world databases is minimal – for VMware ESX Server, we measured CPU overhead to be less than 10%.

* Databases have too much I/O to be virtualized: Databases typically have a large number of small random I/Os, and it is in theory possible to hit a scaling ceiling in the hypervisor layer. VMware ESX’s thin hypervisor layer can drive over 63,000 database I/Os per second, which is equivalent to more than 600 disk spindles of I/O throughput. This is sufficient I/O scaling for even the largest databases on x86 systems.

* Virtualization should only be used for smaller, non-critical applications: The ESX hypervisor is very robust: many customers are seeing over two years of uptime from ESX based systems. In addition, the ESX hypervisor remains stable, even if resources are overcomitted.

Disable denial of service attack detection
This may be necessary of running VMWare server on a Windows host which is not attached to Gigabit ethernet.