Since its inception, the consumer SSD market has comprised a diverse collection of competitors. The makeup is varied in part because of the nature of the components inside contemporary solid-state drives: a controller chip, some DRAM cache, and an array of NAND. There are numerous off-the-shelf options for each category, allowing smaller firms to piece together drives without designing or fabricating any of the actual chips involved. Larger flash manufacturers usually sell complete SSDs in addition to the chips that go inside them, and their drives often use the same third-party controller silicon as those produced by smaller players. As a result, the market is teeming with comparable offerings from a range of vendors.
While just about everyone seems to be getting in on the solid-state party, one group has been conspicuously absent. The biggest desktop hard drive makers have all steered clear of client SSDs. They've made strategic SSD-related acquisitions and produced enterprise-oriented drives. Some have even developed hybrid products that combine mechanical platters with flash-based caches. However, they've ceded the market for high-performance system drives.
Well, at least they used to. We've always known the major hard drive makers would enter the client SSD business eventually, and Seagate has finally made its move. Behold the simply named Seagate 600 SSD.
This nondescript-looking drive comes in enclosures 5 mm or 7 mm thick. 5-mm bays will likely feature in the next generation of ultra-slim notebooks, and I expect the 600 SSD will be available in some of those systems. You probably won't see the slimmer version selling on its own at places like Amazon and Newegg, though. Online retailers are likely to stick with the 7-mm variant pictured above.
The drive's 7-mm case is held together by metal clips rather than traditional screws. Cracking it open required some prying that, while gentle, still mangled the back plate a little. The things we do to bring you naked circuit board pictures. Speaking of which...
All the action happens on this side of the circuit board. An array of eight NAND packages sits on the left, while the controller and DRAM cache lie on the right.
Link_A_Media Devices (LAMD) provides the controller. The little-known firm was purchased by memory giant SK Hynix last summer, right about the time its LM87800 controller started popping up in Corsair's Neutron Series drives. The very same silicon anchors the Seagate 600 SSD.
Why did Seagate select the LAMD controller over better-known solutions from the likes of Marvell and SandForce? Because it had a hand in developing the chip. Seagate worked with LAMD on a portion of the LM87800 as part of a project that didn't make it to market. Despite the fate of that endeavor, Seagate was left with "high confidence" in the design it produced.
The LM87800 wasn't so much chosen for the Seagate 600 SSD as it was inherited from that drive's enterprise-oriented brother, the 600 Pro. The client drive is derived from its server-grade sibling, which shares the same controller and NAND. Seagate selected the LAMD chip in part for its server-friendly performance characteristics, including its high I/O throughput per watt. Considering how well the Neutron Series performed in our server-style IOMeter benchmarks, it's easy to see why.
The LAMD chip features dual ARM processor cores: one to power its 6Gbps Serial ATA interface, and the other to manage its eight parallel NAND channels. There are four chip-enables per channel, so optimal performance requires at least 32 individual NAND dies. Most modern controllers have similar channel configurations.
To combat NAND wear, the LM87800 employs what LAMD calls eBoost technology. This feature promises enterprise-class reliability through the use of "proprietary adaptive signal estimation techniques coupled with powerful on-the-fly error correction technology." As flash cells accumulate write/erase cycles, the voltage window that can be used to represent data shrinks, making advanced signal processing algorithms important to extending the useful life of the NAND.
Endurance is especially important for the Seagate 600 SSD because it features 19-nm MLC NAND. The finer fabrication process is great for squeezing more gigabytes onto each wafer, but it makes the cell walls thinner and more prone to degradation, which reduces their lifespan.
Seagate says 240 and 480GB versions of the 600 SSD can take 72TB of writes before the warranty runs out. If you don't hit the terabyte limit, the warranty lasts for three years. The 120GB model has the same three-year warranty, but it's only rated for 36.5TB of writes during that time.
Confusingly, the datasheet also claims the 600 SSD 240 and 480GB are good for maximum writes of 40GB per day. Over three years, that works out to only 44TB. Seagate says the per-day figure is based on longevity with an "industry standard workload defined by Intel." Intel's own 335 Series SSD is rated for only 20GB per day with typical client workloads, so the 600 SSD's endurance spec looks particularly generous.
|Capacity||Max data written||Max sequential (MB/s)||4KB random (IOps)||Price||$/GB|
Toshiba supplies the Toggle DDR NAND for the 600 SSD. Each of our 240GB drive's eight flash packages has four dies, which adds up to a 32-die config that fully exploits the controller's built-in parallelism. The performance ratings in the table above confirm that the 240GB model is as fast as the 600 SSD gets. The write ratings are lower for the 120GB variant because it has fewer NAND dies connected to the controller.
Seagate's datasheet and product manual disagree on the 600 SSD's performance specs. The figures above were taken from the datasheet, but the manual claims the drive can hit 530MB/s with sequential reads and 440MB/s with writes. The manual applies those numbers to the 120GB model, as well, so I wouldn't put too much stock in them. We'll measure performance for ourselves in a moment.
Normally, I'd tell you all about the 600 SSD's accompanying utility software before moving on to our benchmark results. However, Seagate's SeaTools app hasn't been updated with SSD-specific functions. Seagate says secure-erase and wear-monitoring functionality will be added "shortly." In the meantime, you can track the amount of data written to the drive by watching its SMART attributes with third-party software.
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