1st tests of the Vertex 2 / SandForce SSD
Written by Marc Prieur
To achieve such results, SandForce has developed DuraWrite technology which will lower write amplification under 1x! Remember, the write amplification is the ratio between the volume of data written on the flash memory (flash write) and the volume of data to write requested by the system (host write). Intel has highlighted the fact that it kept write amplification on its SSDs down to 1.1x. SandForce has announced 0.5x and says, for example, that installation of Vista and Office requires a total of 25 GB (host writes), but that in practice only 11 GB are written in Flash (a write amplification of 0.44x).
How is this possible? Obviously this isn’t bit-for-bit data storage and SandForce must have implemented compression and deduplication algorithms within the controller. Of course this technology will work less well with compressed data and write speeds for compressed data will drop to 145.9 MB/s according to AnandTech’s tests, which is in any case not bad.
Reducing flash writes is of course beneficial both in terms of write speeds and reliability as the number of write cycles is critical in terms of how long flash memory lasts. So as to limit wear on the flash, SandForce also includes additional extra internal information similar to RAID5 (without going into more detail) and makes it a point of honour to have a lot of additional flash: the first SSDs will be the 50, 100, 200 and 400 GB versions but they will actually have 64, 128, 256 and 512 GB of flash memory. These are the enterprise versions, with the standard versions having less additional space.
All in all a very promising controller then, although we would have liked to see SATA 6 Gbits/s support.
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