Crucial M4 / Micron C400 256GB SSD ReviewFri, Apr 08, 2011 - 12:00 AM
Crucial m4 256GB – A Look Inside
The Crucial m4 opens right up with the removal of four screws. The PCB itself is not encumbered by fasteners and pulls out easily.
The first side shows eight of the sixteen total NAND modules as well as the Micron branded cache along the edge of the board.
The 25nm NAND is Micron in manufacture and each is 16 GB in density for an overall capacity of 256 GB (in terms of hardware storage 1 GB = 1,000,000,000 bytes). The NAND is rated for 3,000 program-erase (PE) cycles whereas the Intel 320 Series drive we recently tested listed their 25nm NAND as rated at 5,000 PE cycles. They even state in the specifications that 40 GB of writes a day would put the life at five years. Either way, the NAND is likely to outlast its relative usefulness before the user upgrades and NAND loses its charge after roughly 10 years anyway so no one is expecting them to last forever. The speed at which these drives are improving; in just a few years they will be looked at like we see 5400 RPM drives vs. a 10,000 RPM drive today.
The DDR3 cache is a whopping 256 MB and there for buffering duties and sits on the opposite side of the board from the controller which is a bit odd. The 64 GB drive will carry a 128 MB cache.
The flip side reveals the remaining NAND chips along with the controller.
The Marvell controller is the brains of the operation and as before, it supports TRIM and idle garbage collection while using an eight channel configuration. As mentioned, the architecture remains the same but carries new firmware that not only boosts overall performance but allows it to play nicely with the 25nm NAND that’s new to this generation of drives. How much of a speed improvement will bear out in the testing after we have a look at the test system.