If you've been paying attention to the SSD market, you'll know that drives based on SandForce controllers tend to offer less storage capacity than the competition. They typically stick to 60, 120, 240, and 480GB capacities rather than the 64, 128, 256, and 512GB sizes favored by rivals. Now, A-Data has announced a series of "expanded capacity" SSDs based on tweaked SandForce firmware. The new firmware offers additional storage by reducing the amount of NAND capacity set aside for use exclusively by the controller. According to LSI, which now owns SandForce, this move also eliminates the RAID-like RAISE redundancy scheme that protects SandForce-based SSDs from data loss due to unexpected flash failures.
Cutting an SSD's spare area can affect performance, but A-Data's specifications suggest the new drives will be competitive with current offerings. The flagship XPG SX900 can purportedly crank out 85,000 4KB random-write IOps and push sequential read and write speeds as high as 550 and 530MB/s, respectively. One rung down the ladder, the Premier Pro SP900 offers nearly identical speed ratings; the only difference is its 520MB/s sequential write rate, a drop of just 10MB/s. Both of those models come with 6Gbps Serial ATA connectivity, and has a cheaper Premier SP800 that's limited to 3Gbps SATA speeds. The SP800 is restricted to 32 and 64GB capacities and offers about half the performance of its 6Gbps siblings.
The XPG reportedly uses synchronous NAND, while the Premiere Pro is equipped with asynchronous memory. We've observed substantial differences in real-world performance between other SandForce SSDs with similar memory configurations, making me a little dubious that A-Data's specs represent the true performance of the new drives—and their expanded-capacity firmware. When the last generation of SandForce SSDs switched from enterprise-style 28% overprovisioning to the 7% OP typical of consumer drives, performance dropped with both sequential and random writes.
A good argument can be made for giving up a little performance in exchange for more capacity. SSDs are plenty fast, but they're almost always too small for all the data, games, and applications one might want to store. We'll have to put these higher-capacity drives to the test to get a better sense of the trade-offs involved.
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