The heart of Corsair Force GT: SandForce SF-2281
The models presented at CeBIT 2011 by Corsair, including the Corsair Force GT, are characterized by the use of a second generation SandForce chip, which allows you to use the 6Gbps SATA III controller; specifically the Force GT features a SandForce SF-2281. Among the main features of this new controller is the ability to simultaneously access the 8 NAND Flash modules, each module has a capacity of 8GB.
The NAND flash memory cells present on the PCB of the drive we're going to review are 16, divided into two groups of 8, one on each side of the PCB. The memories, MLC type (Multi Level Cell) have a 25nm production process and totally provide 120GB of capacity (8GBx16=128GB). The remaining 8GB are devoted to disk protection in case of a failing Flash Block. The NAND flash memory cells are certified by ONFI (Open NAND Flash Interface), which simplifies the interaction of memory chips in desktop products. The use of 25nm cell while leading to an increase in space devoted to over provisioning, or the additional space dedicated for the replacement of a dead cell, the other leads to a slight decrease of life of the chips that are less lasting than those produced in 34nm.Making use of 16 modules NAND memory instead of the classic 8 (one per channel) might seem a disadvantage, but in reality, since the NAND memory cells employ a certain amount of time to retrieve the data, while one is engaged in the operation research, the other can perform other operations, so as to saturate the communication channel, thus acting in parallel; thereby optimizing the use of the canal, you experience superior performance in both read and write. Thanks to the many technologies implemented by the second generation SandForce controller, the possibility of loss of data due to corruption is almost nothing compared to traditional HDDs.
Like all other last generation SSDs also the Corsair Force GT supports the TRIM function and therefore the performance gap that the first models of SSDs experienced with the passage of time during read and write operations has been virtually wiped out.
The second generation of SandForce controllers also improves the number of input/output per second (IOPS) compared to the previous versions of the same controller; the model we reviewed, reaches the 85K IOPS. Besides this, the SF-2281 controller natively supports garbage collection; this function is independent of the operating system as opposed to the TRIM technology, it takes note of the areas of memory not allocated from a process and makes them available again. In the case of SandForce controllers, the garbage collection function was called Recycling and has been implemented in order to have less impact on the durability of flash memory. Another very important feature of the SF-2281 controller is a suite of technologies called DuraClass (of which SandForce is the sole owner). It integrates the DuraWrite functionality, which streamlines the process of writing the flash memory, with similar effect to that of wear leveling.
The SF-2281 controller, like its predecessors, continues to support the RAISE (Redundant Array of Independent Silicon Elements) functionality similar to RAID, but that increases the integrity of data written and a better efficiency than RAID 1. Exploiting chips parallelism handled by the controller, data is distributed across multiple chips, while improving performance and providing greater protection in case of loss of data blocks. In fact, if the data were stored contiguously, the likelihood of being able to correct errors in a block is dramatically reduced.
