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Will we see more PCIe-based flash storage access similar to EMC's DSSD?

Attaching flash directly to the PCI Express bus offers very low latency, but space is limited for on-board server-side flash. PCIe-based access for storage arrays may be the answer.

The answer to this question is yes and no. On the surface, DSSD looks like an all-flash storage array directly connected to a server via PCI Express (PCIe). In that regard, I absolutely expect to see some competition from other vendors relatively soon.

One of the problems with flash storage is disk controller latency. SATA and SAS controllers aren't as fast as some flash drives, so the controllers become a bottleneck. That's why there has been so much interest in PCIe-based flash storage lately. The problem is that internal PCIe-based flash devices have a very limited capacity. Organizations that need higher capacity often turn to flash arrays, but common means of connectivity are generally slower than PCIe. Connecting to an external storage array via PCIe is a great way to access high-capacity flash storage without the latency of a slow bus. In that regard, I do think PCIe-based access to all-flash arrays will become more popular.

However, DSSD is about more than just low-latency, high-capacity storage. The thing that makes DSSD so unique is that it can interact directly with applications via a set of APIs. While a traditional flash array is exposed as storage, a DSSD array can be exposed as storage or memory. This means the storage can be used for tasks that were once performed in memory. For instance, an in-memory database could be hosted on a DSSD array for a fraction of the cost of running the database in RAM.

It's possible that other vendors will adopt an approach similar to that of DSSD, but I think it will take a while. Developing the storage architecture, necessary protocol stacks and APIs will require a significant investment, so I'm guessing other vendors will wait to see how the technology is received prior to developing competing offerings.

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