Strange as it may seem, virtualization can improve the performance of some web hosting applications. AMD, a major chip maker, found that overhead caused by virtualization doesn’t always cause performance hit.
A big player in the virtualization industry, VMware, has worked closely with Intel and AMD to get the most of virtualization extensions integrated in current multi-core processors. AMD, for example, has been experimenting with an open-source caching system called Memcached that can be implemented in large cloud-based services, including Twitter, Youtube, WordPress and Digg. Memcached can speed up server performance by taking the load off back-end databases.
Unfortunately, there is an issue with Memcached and that really comes down to the fact that Memcached is quite old by current Web hosting standards. The service was developed in 2003, when web hosting industry still employed mostly single-core servers. In its original form, Memcached is thread-limited and its performance can hit a brick wall, when it needs to work with 4-6 threads. A thread-limited caching system can bring problem for web hosts that repeatedly need to scale up their infrastructure due to increased workloads, simply by chucking more processors won’t help. This is an especially vexing issue for AMD, because its business revolves around selling more and more processors to the customers. And this is where server virtualization comes to play.
To get around this issue, AMD experimented with an Opteron server, which uses Red Hat Linux for operating system, VMware ESX for virtual hosting and Memcached. The tricky part is to balance throughput with system utilization and average delay to come with the correct configuration that offers the highest performance level without putting too much pressure on the server resources.
Eventually, after much mucking about, they got a significant improvement in throughput (up to 300 percent) when running 12 virtual machines and Memcached, compared to running Memcached without virtualization. This is a quite paradoxical result and it shows that virtualization can help you solve bottleneck, even when applications used are thread limited. In essential, experts have found that the performance benefit of virtualization can far outweigh the performance hit caused by excess overheads. This way, when performed correctly, web hosts can achieve better system throughput on the virtual dedicated hosting servers, this is an unsung benefit of virtualization.
In addition, AMD discovered that with Memcached throughput tends to scale linearly with the number of active virtual machines (VMs) until it hits the hardware limitation. It shows with the right caching system, web hosts can get the most of their hardware resources. This is certainly good news for web hosts that actively offers virtual dedicated web hosting plans and they can simply optimize their servers by adding more VMs until optimized performance level is achieved. What’s more, AMD as a hardware maker will definitely benefit from this development.
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