The Crucial C300 series of SATA 6Gbps SSDs tore through our benchmarks last year, and as the only SATA 6Gbps SSDs on the market, the range had a palpable performance advantage over any other drive available. The read speeds of over 340MB/sec offered tangible performance improvements over SATA 3Gbps SSDs, and were matched by excellent random read and write performance and effective TRIM execution.
As the drive reads and writes data in a 1:1 ratio, rather than relying on compression techniques as in the case of SandForce controller-based drives, performance was consistent no matter what data the C300 was handling. With SandForce-based drives, performance can vary according to whether or not the data it's handling is compressible.
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The C300's successor appears in the oddly renamed guise of the Crucial M4 rather than something more logical, such as the C400. Oddly Crucial's parent company Micron is releasing the drive as the C400, but only as a business product. It seems an odd decision to change the branding, and even more disappointing is the fact that the internals of the drive aren't radically new either.
The Marvell 88SS9174-BLD2 drive controller is merely an updated version of the Marvell 88SS9174-BJP2 chip used in last year's line of C300 SSDs. However, the M4 does have a massive 256MB DRAM chip on the rear of its PCB to act as a cache.
The newer revision of the Marvell drive controller (left) and the older BJP2 chip used in the C300 range (right).
While Crucial had the Marvell SSD controller range to itself for most of last year, other SSD manufacturers are now using similar Marvell chips for their drives. Intel, Corsair, and other high-profile SSD makers are also producing new Marvell-powered ranges of SSDs.
All versions of the M4 (there are 64GB, 128GB and a 512GB models too) use the same PCB, with the NAND chips connected to the controller via eight channels. Performance is largely dependent on the density of NAND modules used: in this 256GB model, there are 16 chips (two per channel) of 16GB 25nm Micron NAND. Lower capacity drives use lower-density NAND, resulting in reduced performance.
With only minor improvements in the controller and NAND chips, much of the difference between the C300 and M4 is found in the drive’s firmware. When we spoke to Crucial at CES earlier this year, we were told that some random performance had been sacrificed to improve sequential speeds. Rated at 415MB/sec sequential read and 260MB/sec sequential write, the M4 claims to deliver a 20 per cent increase in sequential speed over the C300.
Interface SATA 6Gbps
Nominal capacity 256GB
Formatted Capacity 238.47GB
Controller Marvell 88SS9174-BLD2
Cache 256MB DDR2
Memory type/amount 16 x Micron 16GB 25nm NAND flash