On the flash memory front, vendors are working to increase not only the density, but also the useful capacity and life span of flash memory used in server-based flash storage and SSDs.
The NAND flash on which most flash and SSD drives are based will begin to be replaced by a new form of nonvolatile memory called phase-change memory by around 2016, says Milan Shetti, CTO at HP Storage. Unlike magnetic recording that records data by changing the magnetic orientation of a physical piece of memory, PCM applies heat to change the electrical conductivity of the media. PCM drives are not only faster than NAND flash, but their memory cells can also withstand two to three times the number of read/write cycles as NAND flash, says Haris Pozidis, manager of memory and probe technologies at IBM's Zurich research lab. That's important for applications such as caching where data is constantly being read and written.
Shetti predicts initial drive capacities of about 200 to 250GB, with drive sizes at least doubling by 2018. He stresses that this will all be usable capacity, which is not the case in current SSDs, where 15% to 20% of raw capacity is set aside to replace cells that may wear out. Shetti says he expects prices per gigabyte to be comparable to those of current flash drives. That equates to a 15% to 20% price cut, since all of the raw capacity will actually be usable.
Dedupe: A Must-Have Feature
Over the past 10 years, deduplication -- the process of eliminating duplicate copies of data -- has moved from game-changing novelty to must-have feature.
Observers say not to expect any breakthrough increases in the amounts of data that deduplication can remove from hard drives. Currently, deduplication typically reduces data by a factor of seven to 10. Future improvements will come from increases in the speed at which data is deduplicated and from the use of standard deduplication systems across an enterprise.
Speeds will improve as a result of deduplication being performed in hardware rather than software, and in nonvolatile memory such as PCM, which is faster than today's NAND flash, observers say. Predicting that "every [nonvolatile memory] controller is going to have [deduplication] built in," Shetti also points out that, unlike disk drives, deduplication doesn't cause defragmentation on nonvolatile memory drives.
In-line deduplication, in which data is deduped before it is ever stored, reduces storage requirements from primary storage to backup and replicated copies. Pure Storage says its in-line data deduplication allows its flash arrays to store five or 10 times as much data as their designated size.
Observers also expect to see deduplication spread from its traditional use in backup to other applications and to more computing and storage devices. Dell says it plans to incorporate the deduplication technology it gained through its purchase of Ocarina into its EqualLogic and Compellant product lines, "first with compression primarily for... data like snapshots," and later for more frequently accessed data and files, says Travis Vigil, executive director for product marketing at Dell Storage.
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