Read vs Write Performance
Like sequential and random, the names read and write give you a pretty good indication of what they are referring to. Basically when a drive is reading data, it is accessing data that is already stored on it. When it is writing, it is placing new information on the drive. How close those numbers are to each other depends on how the drive was designed. For example, some manufactures want extremely high reads and are willing to sacrifice write performance to get it, while others try to stay fairly even.
For general purpose use, read speeds are going to be more important because most of the time you are accessing data that is already on the drive. But if you plan on doing heavy file manipulation or will be transferring files to the drive often, write speeds will also be important.
Compressible vs Incompressible Performance
Of all the areas we have discussed so far, this is the one most abused by SSD vendors. Put simply, compressible data is data can that be reduced in size with lossless compression, while incompressible data can not be shrunk any further with lossless compression. How does that translate to abuse you might ask? Well depending on how the drive was designed, some drives are very good at compressible data and not so good with incompressible, while others are decent at both. What this leads to is companies claiming only their extremely high compressible data performance on the box with no mention of incompressible, which is a little misleading and unfair to companies that choose to balance the two.
Most files are at least somewhat compressible, and things like operating system files, text documents, and certain photo file types like bitmap are usually very compressible. Incompressible data includes programs, video, sound, .zip files, and certain photo file types like JPEG. Benchmarks that test using incompressible data (AS SSD) are usually considered closer to “real-world” performance than pure compressible benchmarks (ATTO).
Good post guys, very informative for people who don’t know that much about SSD’s!