Why SSD based arrays and storage appliances can be a good idea (Part II)

Part 2 of the good post from Greg Schulz (thank you)

This is the second of a two-part post about why storage arrays and appliances with SSD drives can be a good idea, here is link to the first post.

So again, why would putting drive form factors SSDs be a bad idea for existing storage systems, arrays and appliances?

Benefits of SSD drive in storage systems, arrays and appliances:

  • Familiarity with customers who buy and use these devices
  • Reduces time to market enabling customers to innovate via deployment
  • Establish comfort and confidence with SSD technology for customers
  • Investment protection of currently installed technology (hardware and software)
  • Interoperability with existing interfaces, infrastructure, tools and policies
  • Reliability, availability and serviceability (RAS) depending on vendor implementation
  • Features and functionality (replicate, snapshot, policy, tiering, application integration)
  • Known entity in terms of hardware, software, firmware and microcode (good or bad)
  • Share SSD technology across more servers or accessing applications
  • Good performance assuming no controller, hardware or software bottlenecks
  • Wear leveling and other SSD flash management if implemented
  • Can end performance bottlenecks if backend (drives) are a problem
  • Coexist or complemented with server-based SSD caching

Note, the mere presence of SSD drives in a storage system, array or appliance will not guarantee or enable the above items to be enabled, nor to their full potential. Different vendors and products will implement to various degrees of extensibility SSD drive support, so look beyond the check box of feature, functionality. Dig in and understand how extensive and robust the SSD implementation is to meet your specific requirements.

Caveats of SSD drives in storage systems, arrays and appliances:

  • May not use full performance potential of nand flash SLC technology
  • Latency can be an issue for those who need extreme speed or performance
  • May not be the most innovative newest technology on the block
  • Fun for startup vendors, marketers and their fans to poke fun at
  • Not all vendors add value or optimization for endurance of drive SSD
  • Seen as not being technology advanced vs. legacy or mature systems

Note that different vendors will have various performance characteristics, some good for IOPs, others for bandwidth or throughput while others for latency or capacity. Look at different products to see how they will vary to meet your particular needs.

Cost comparisons are tricky. SSD in HDD form factors certainly cost more than raw flash dies, however PCIe cards and FTL (flash translation layer) controllers also cost more than flash chips by themselves. In other words, apples to apples comparisons are needed. In the future, ideally the baseboard or motherboard vendors will revise the layout to support nand flash (or its replacement) with DRAM DIMM type modules along with associated FTL and BIOS to handle the flash program/erase cycles (P/E) and wear leveling management, something that DRAM does not have to encounter. While that provides great location or locality of reference (figure 1), it is also a more complex approach that takes time and industry cooperation.

Read on here

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