28
Aug

While you should be able to count on an all-solid-state storage system to deliver better performance than an array of spinning disks, the differences among solid-state systems are at least as significant as those among disk-based systems. While most storage professionals can generally identify a disk array as fitting into the high-end, midrange or value market segment, many have not yet recognized that the market for all-solid-state arrays also breaks down into market segments.

While performance is the main reason we buy any solid-state storage system, some users–including many employed by three-letter agencies of the federal government who would have to kill us if we ever found out exactly what they were doing–are looking for the ultimate in performance and don’t care about anything else.

If speed is what you need and cost is no object, the solution is a rack-mount DRAM SSD from vendors like Texas Memory Systems or Solid Access that can deliver 10 to 20 microseconds of latency for a measly $700 per gigabyte. DRAM SSDs are the drag racers of the data center: Like a dragster they’re really fast but only good at one thing, and they generally lack redundancy, capacity and comfort–that is, management functionality.

If you want enough space for your girlfriend, or more than about 1 Tbyte of data, you should look at flash or hybrid DRAM and flash systems from the likes of Violin Memory or Kaminario. They’ll deliver millions of IOPS and latencies on the order of 100 to 300 microseconds, but are still limited in terms of capacity and management flexibility, topping out at well under 50 Tbytes. These are the Lamborghinis and Bugattis of the data center. They’re so fast that ordinary storage administrators lust after them, but they don’t have room to take the kids and luggage to the beach for the weekend, and suspension so stiff that driving them in the city is a painful experience.

Mere mortals have to settle for all-solid-state arrays in the price-performance category. Vendors like GreenBytes, SolidFire, Pure Storage, Nimbus and Whiptail have feature-rich arrays with redundant controllers and support for multiple storage protocols, snapshots and/or replication. Many of these systems are price-competitive, with arrays full of 15K RPM disks as the vendors use data-reduction techniques like compression and data deduplication to squeeze more data into their expensive SSDs.

These systems deliver only hundreds of thousands of IOPS and can have peak latencies as high as a millisecond. Since a 15K RPM disk drive has about 4 milliseconds of latency, and it would take thousands of drives to get 100K IOPS, these systems are still blazingly fast in comparison to even a high-end array full of disks. I consider the price-performance arrays the BMW M5s of the storage world: While they can’t run at more than 200 mph, like the Lamborghinis, they seat four and have enough trunk space for more than just a set of golf clubs.

Shopping for an all-SSD array is like shopping for a fast car: You’ll have to decide how fast is fast enough, remembering that speeding up storage by a factor of five or more may just reveal bottlenecks in your servers or network.

Disclaimer: SolidFire is a client of DeepStorage LLC.

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