Another year is upon us and so is another round of speculation that solid-state storage is on the verge of taking over the enterprise. We’ve been hearing this for the past several years, of course, but is it possible that maybe, just maybe, they could be right?
Performance has never been much of an issue in this debate, given the speed disparity between the technologies and the increasingly large capacities that solid state is achieving. And while prices have dropped dramatically for flash and other types of non-magnetic storage, most enterprises seem content to delegate SSD infrastructure to high-speed, high-priority workloads, which leaves plenty for hard disks to do in the data center.
The question, then, is whether SSDs will ever achieve cost parity with traditional media, or will it always command a higher price due to its stronger performance characteristics? To hear some people tell it, that parity has already arrived, especially when you look at the bigger picture. According to IBM honcho Steve Mills, an apples-to-apples comparison of current prices would show bulk storage hard disk costs of about $2 per GB, jumping to about $6 per GB in high-performance applications. That’s still lower than the $10 per GB of solid state, but not when you factor in things like the memory lost to short-stroking and the reduced hardware requirements of SSDs.
Even so, won’t there always be workloads best suited to hard disks? After all, many enterprises still use tape, and besides, says Hitachi CTO Hu Yoshida, disk technology still has one thing going for it: durability. Disks provide close to 10-times the number of re-writes of MLC flash, and even with advanced controller technology, flash has only about a five-year lifespan under normal conditions – nowhere near the typical HDD. In all likelihood, then, future enterprises will pursue hybrid storage infrastructure, with active data residing in flash tiers.
But what if the durability issue were removed? Wouldn’t that provide a major pendulum swing in SSD’s favor? Queue IBM again. The company recently announced a $1 billion research program into flash technology, and it has made no secret of its support for phase-change memory technology. If initial reports are accurate, PCM provides multiple millions of read/write cycles, far out-classing HDD’s 30,000 or so. It is still unclear how close to commercialization the technology is, but a billion dollars can certainly buy one heck of a lab to find out.
In the meantime, new generations of data management and other support technologies are turning their eyes toward solid-state environments. Indra Networks, for example, recently came out with a new system aimed at boosting compression/decompression capabilities in flash-based infrastructure without diminishing overall performance. The ZopSSD appliance functions with everything from PCIe-based memory systems to full SSD arrays and is able to implement decompression in the read path at speeds up to 20 Gbps. This allows it to operate at data rates similar to SSD processing speeds, eliminating the slowdown that even the highest performance compression engines generate when applied to solid-state infrastructure.
But does any of this really mean the hard disk is doomed? Probably not right away. Even those espousing the all-flash data center concede that they are best at handling high-transaction, web-facing operations, which represents a growing portion, but certainly not all of the enterprise data ecosystem.
That means hard disk, and yes, even tape, will continue to serve ably at many facilities, although probably not for the most important data.