Flash storage solves specific problems that data centers face as the number of virtual machines per host increase. The combination of server-side and network-based flash solutions can solve problems like server RAM issues, network bottleneck issues and overall storage performance.
Density Is Job 1
Intel has done an incredible job increasing the processing power its CPUs can provide, and VMware has done an equally impressive job of taking advantage of that power. In theory, a physical server can now support dozens of workload-critical virtual machines. But reality shows that the rest of the environment quickly breaks down long before those densities are reached. Dozens of virtual machines take RAM in order to operate, and they also generate random I/O that needs to be funneled through the storage network and acted on by the storage system.
Flash Is The VM Enabler
Flash, at all levels, can eliminate much of these challenges and now can do so very cost effectively. For example, flash in the server can act as a virtual memory pool allowing you to under-provision RAM resources and then rapidly swap memory as needed. This keeps costs down and allows for terabytes of memory to be installed in the physical server. Flash in the server can also act as cache for the shared storage. This removes a portion of the traffic from the network (about 60%) and provides near-instant response to applications with cached data. Finally, shared flash can allow those 40% cache misses to be responded to nearly instantly.
Which Flash First For VMware?
The paragraph above gives a quick overview of just some of the flash options available to VMware administrators looking to improve the density per physical server and the overall performance of the environment. I am often asked which one should be implemented first. Unfortunately the answer will vary, depending on a lot of factors. For example, if you have just a few servers that need better performance and your data set is cache friendly (mostly reads), then a few server-side solid-state drives (SSDs) with caching software may be more than enough. If you have a larger environment with lots of hosts to be accelerated, then the economics of an all-flash storage system may make sense.
The truth is many flash solutions on the market can help your VMware performance. Some may take more effort and dollars than others, but they can be made to work. Deciding on the right solution that gives you the ability to maximize your VM density will be driven by your budget, what your current environment requires in terms of performance, and what its condition is now. We'll be at VMworld to provide information on these solutions, so stay tuned.