What Solid State Storage Form Factor Is Best? Part III

In our series on trying to decide which Solid State Storage is best for your environment we have covered PCIe Based Solid State Storage and Solid State Disk (SSD). This entry will cover Solid State Systems (SSS) or Memory Arrays. These are systems that are designed from the ground up to only provide solid state storage. As a result they bring a different set of advantages and disadvantages that need to be considered.First, because solid state storage systems are not bound by the realties of having to support hard disk drives (HDD) they can break a few of the physical laws that govern what you can do with HDD. The HDD needs space. When too many are housed closely together the vibration, power and cooling issues can lead to drive failure. As a result there is typically a limit to how many drives you cluster together in a single shelf. Solid state storage on the other hand has none of these issues, while you need some airflow for cooling, there is no concern over vibration. As we discuss in our recent article "What is a Memory Array?" the solid state only solution's dense capacity is a key in driving down the cost of solid state storage in the Enterprise.

Second, because solid state systems do not need to be concerned about backward capability to older drive technologies they are designed to deliver the performance capabilities of a fully populated system. The challenge with integrating SSD into legacy systems is that in many cases three or four SSD drives are faster than the bandwidth of the entire shelf leading some manufacturers to provide quotes with half or less populated SSD shelves. This of course impacts the above pricing issue by making density even worse than what was mentioned above. The result is that the SSS type of solid state storage compares favorably to the PCIe type of solid state storage from a performance perspective. The difference being one is internal (server based) and the other external but both seem to be the choice for top end solid state performance while keeping cost per GB reasonable. PCIe also has a capacity disadvantage since it is limited to how much memory can be placed on a card and how many cards can be placed in a server.

To summarize where we are from a "which is best" standpoint; SSD, solid state designed to look and act like a drive, has the advantage that it is plug compatible with the storage mechanism that dominates the market today, the HDD. SSS has the advantage in performance, capacity and density. PCIe has a similar performance advantage but only in local servers with limited capacity needs. All should deliver a performance boost if mechanical storage is your bottleneck. The selection of which SSD depends partly on how much of a boost you need and how heavy you weigh the other factors of price and capacity. Included in the decision process should be the issue of sharing and integration into the existing storage fabric and its data services, which will be the subject of our next entry.

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George Crump is lead analyst of Storage Switzerland, an IT analyst firm focused on the storage and virtualization segments. Find Storage Switzerland's disclosure statement here.