Competition – and differentiation – in the solid-state drive (SSD) space grew more intense today with Intel Corp.'s declaration that it will ship its first enterprise-class SSD and a new SSD for mainstream computing by the end of this year.
The X-18 M and X-25 M will be available over the next 30 days. The "M" stands for "mainstream," and the drives are for use in PCs, notebooks and other consumer computing applications. They come in 80 GB and 160 GB capacities, and 1.8-inch and 2.5-inch form factors, with a 3 Gbps SATA II interface. Read performance is 250 MBps, while sequential writes are about 70 MBps.
The X-25 E, or "Extreme," is set to follow in 90 days with smaller capacity – 32 GB and 64 GB models – and a sequential write performance that has been clocked in internal tests at 170 MBps. Also, 4 KB random-read IOPS have been measured at 35,000 per drive, and random writes at 3,300. According to Intel, this boost in performance comes from having parallel access through 10 I/O channels to each die in the enterprise version of the drive.
While these drives, like other SSDs on the market, have yet to overcome the disparity between read and write performance on NAND flash, Intel has architected the drives to be more reliable than other SSDs.
One of the major issues with SSDs today, along with cost and write performance, is durability, which is a two-fold problem. First, SSDs are subject to a phenomenon known as "write amplification," because memory cells must first be erased completely in 1 MB chunks before new bits of data can be written. Most SSDs transfer the contents of the block to be erased to DRAM for new bits to be added, and erase the contents of the cell before transferring the newly reconstituted cell back to the NAND die it came from.
Knut Grimsrud, Intel Fellow, director of storage architecture, said this process can involve up to 32 I/O operations within the SSD over the original write from the application. Because NAND has a finite number of write/erase cycles, this can shorten the life of the medium. For the X-25 E, Intel claims each write I/O uses just 1.1 times the number of writes within the SSD.
Intel won't divulge how that process works, claiming that such information is proprietary. Similarly, Intel also said its SSDs have special algorithmic efficiencies for wear leveling among the individual NAND dies within the SSD. Intel measures wear-leveling efficiency by comparing the total number of cycles put on the most-used block with the total number of cycles put on an average block, Grimsud said. This comparison is expressed as a ratio. He said this ratio can be 3:1 in some SSDs. With the X-25 E, Intel claims that internal testing shows the most-cycled block with 10% more cycles than average, or a ratio of 1.1:1. "In terms of cycling endurance, a factor of three difference in the wear-leveling performance also has material impact on overall reliability," Grimsrud said.
Intel has not yet set pricing for the drives or identified OEM partners who will use its drives, but a video within an Intel press kit showed officials from Hewlett-Packard and Lenovo saying the mainstream drives will be put in their laptops. The video also included comment from John Fowler, Sun Microsystems' executive vice president of systems, who said Intel will join Samsung in supplying Sun its drives for upcoming hybrid storage devices.
IDC analyst Jeff Janukowicz said while it's unclear what exactly the mechanisms are behind Intel's longevity and reliability claims, "This is how we're going to start talking about SSDs going forward – we're going to be looking for vendors to differentiate according to these features."
Meanwhile, Intel's brand recognition will give the whole market a boost by definition, Janukowicz said. "Their brand brings a lot of validation to the SSD market," he said. "They're also bringing knowledge of PC and enterprise controller workloads, which are important to architecting SSDs."