The typical path to SSD is by either buying a SAN attached SSD specific storage system or leveraging SSD drives in an alternate drive type in a storage system. For a few years however another form factor has been establishing itself, the PCIe based SSD and there may be some areas where it has a few advantages.The PCIe based form factor for SSDs is relatively straight forward. The memory, typically Flash, is installed on PCIe card into a server. The server will then treat that PCIe SSD as if it were an internal drive. As we discuss in our article "Pay Attention to Flash Controllers when Comparing SSD Systems" there is more to these systems than just some memory on a card. The investment in engineering that the company makes in the SSD controller is an important differentiator and we have seen it even more dramatically in PCIe based SSD.

The first advantage the PCIe based systems have is that they can be a simple solution to a specific performance problem. For example if there is one server in the environment that is continuously struggling with storage I/O issues, installing a PCIe based SSD can eliminate that problem. These SSDs are often large enough that the whole database can be loaded onto them making a dramatic improvement in performance. While we don't normally support a sledgehammer approach to problem solving, it does get the job done.

The second advantage is the PCIe SSD can resolve the problem in an "off the radar" fashion. They can be installed in the problematic server directly, no changes to the storage network or additions to the storage system need to be made. As a result we have seen many early adopters not be storage managers but server managers and database managers that don't want to go through the "red tape" of upgrading the SAN. The cost profile of the typical PCIe based SSD lends to it being attributable to the server or database budget. There is a concern that the data on these cards will no longer be part of the data protection strategy. As we discuss in "Integrating SSD and Maintaining Disaster Recovery" this can be stepped around by using a mirroring technology that does preferred reads to solve that problem as well.

These are not just for direct attached situations either. PCIe SSD may be ideal couplings with the storage as software solutions that are available on the market. The PCIe SSD card can be installed in the appliance that is also going to run the storage software and the capacity on that SSD be shared to the connecting servers. Depending on the storage software this can also be used as a very large cache to accelerate overall system performance as well.

The most compelling part of PCIe SSD is their price points. The cost of these systems is often well below $15k, supporting that "off the radar" sort of purchase. Is it right for you? If you have a specific I/O problem to address or if you are going to be using a software based storage system then they are certainly worth consideration.

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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.