The first card type we will examine is the PCIe solid state card. This is a card that installs inside of a server. Being PCIe based gives the board more power than the standard solid state drive style of device which allows it to power more flash cells. Being PCIe based also gives the CPU the purest access to the solid state disk than any of the other connection types. This means that PCIe based systems have fewer bottlenecks to contend with.
The downside to the card is that while there is more capacity per card available there is a limit to how many cards you can install into a system. They are ideal for 500GB performance problems, not 2TB performance problems. The also require operating system drivers in order to work. If you are running Windows you are probably safe, any other OS can be hit or miss. Installing PCIe SSD is also typically a disruptive upgrade. You'll have to power down the server, install the drivers for the PCIe card and reboot the server. Finally you can not boot from PCIe solid state storage. So these cards are ideal for cache areas, or for a storage location for swap and database temp files. Of course the size is such that in many cases the entire database can fit on the card.
Where PCI solid state can be very compelling is as less expensive RAM instead of thinking of them as storage. RAM is expensive, you usually buy more to increase the cache area that a database can use before having to resort to accessing the information on spinning storage. Since PCIe is so fast it can act as slow RAM with one key advantage, it is persistent. Data lost in cache when a server crashes is data that is lost forever. Data storage on a flash PCIe card when a server goes down is still there when the server comes back up. The objective with this configuration is to lower the amount of RAM installed in the server and lower the amount of cache that your application is allocated and then redirect that area to storage, just have that be the PCIe based storage.
PCIe solid state provides cost effective high performance storage without the bottleneck concerns of other solid state form factors. PCIe has its place in the infrastructure, and it shouldn't surprise you to expect to see PCIe solid state used in conjunction with other solid state devices; they may not always be competitive to the other forms of solid state storage. In our next entry in this series we will cover the drive form factor of solid state disk.
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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.