As the first range of SSDs to genuinely take advantage of SATA 6Gbps speeds, Crucial’s C300 drives have a huge advantage over the competition, beating Indilinx and SandForce to the SATA 6Gbps punch by many months. However, as the C300 uses a conventional SSD controller (unlike SandForce’s compression based SF-1200), the performance of a 64GB drive can be very different to that of the 256GB model we reviewed originally. The reduced NAND density, or simply the reduced number of NAND modules able to be simultaneously addressed, can cut performance considerably. How much? That’s what we’re going to find out.
The C300 64GB uses the same Marvell controller as the 256GB version. Click to enlarge
Other than its reduced capacity, the Crucial C300 64GB is identical to its larger siblings on the outside, with not even a label to show its capacity. Even when cracking open the 2.5in casing, there’s little to differentiate the two drives. The C300 64GB uses the exact same dual-core Marvell 88SS9174 BJP2 drive controller as the rest of the range, and even uses what is, as far as we can tell, the same 128MB DRAM cache too (although the part number is different).
The difference, of course, is the NAND flash modules used, but unlike Intel’s X25-M series of drives, Crucial has chosen to ship the C300 with an identical number of NAND modules across the range; instead Crucial reduces the module density of the chips. Whereas the 256GB drive ships with 16 Micron 16GB NAND chips, the 64GB packs 16 4GB modules, allowing the smaller drive to deliver theoretically identical sequential and random read performance to its bigger brother. Other than the reduced density of the NAND, it’s still the same ONFI (Open NAND Flash Interface) 2.1-certified, high-speed NAND as used across the C300 range.
The 64GB model uses the same 128GB cache as the 256GB version too. Click to enlarge
The reduction in NAND density does significantly reduce the drive’s sequential and random write speed though. The 64GB model claims sequential write speeds of 70MB/sec and a random 4k IOPS (input/output operations per second) performance of 15,000, compared to the 256GB version’s 215MB/sec sequential write speed and 45,000 IOPs. While the IOPS figures are purely theoretical (random performance depends enormously on the number of outstanding or queued operations), these quoted speeds still indicate that the C300 64GB writes at just over 30 per cent of the speed of the 256GB model.
The payoff for this massively reduced write performance though is a much, much friendlier price tag. The 256GB version tips the scales at a touch under £500, while the 64GB is just £120. However, when you compare the price per formatted capacity, the two drives are roughly the same value - the 64GB costs £2.02/GB while the 256GB version £488 costs £2.04/GB.
What we really need to find out is whether the reduced price of the 64GB is worth the reduced write performance.