Overall there are three basic ways to implement flash SSD in the environment. First, SSD can be added or installed to a server's drive bays via drive form factor solid state or via a PCIe card slot. Second, an appliance can be added to the network that either acts as a standalone storage system or as a cache for an existing storage system. And finally, SSD can somehow be integrated into a storage system.
Which one of these you should pick is largely dependent on two factors. First, how many servers are giving you a performance problem? Second, where are you in your storage refresh cycle? If you have one server that is giving you a particular performance problem, then SSD in the server is the quickest and often least expensive fix. First you have to make sure the application can leverage the flash device by having the ability to change hot-file locations, or you have to buy a caching solution (of which there are many now).
We are finding that the scenario of a single application being the only performance problem is becoming increasingly rare as the environment becomes more and more virtualized. This is especially true in the midsize data center, which tends to have much higher virtualized server ratios. If you have several virtualized hosts then a flash/SSD appliance or a hybrid storage system may be a better fit.
Flash/SSD appliances are ideal for adding to an existing infrastructure to extend the life of the current storage system. These flash-only systems have typically been out of reach of the midrange data center. Now, though, we are seeing shareable systems become available at a much lower cost and with a simple software feature set. The expectation is that you will leverage the storage management capabilities within the hypervisor instead of paying for them again in the storage system.
Hybrid systems are a new generation of storage systems that do more than just add flash to existing legacy storage solutions. They are typically custom built to support flash and its performance capability. When the time comes to refresh the storage infrastructure, these systems are well worth considering. As we will discuss in our upcoming webinar, "The Four Advantages to Hybrid Flash Arrays," these systems allow the data center to leverage the use of solid state across a wide range of physical hosts, but still leverage HDD to keep costs in check.
In reality there is no perfect single solution for all midsize data centers; much of the choice depends on where you are in your storage refresh cycle and the design of the environment. Considering that most midsize data center are highly virtualized, any SSD investment will have to have be accessible by multiple server hosts either through local servers to hypervisor coordination on a storage network.