SanDisk Extreme 240GB SATA 3 SSD Review – Equal 4k Read/Write IOPS Performance Observed


ATTO Disk Benchmark is perhaps one of the oldest benchmarks going and is definitely the main staple for manufacturer performance specifications. ATTO uses RAW or compressible data and, for our benchmarks, we use a set length of 256mb and test both the read and write performance of various transfer sizes ranging from 0.5 to 8192kb. Manufacturers prefer this method of testing as it deals with raw (compressible) data rather than random (includes incompressible data) which, although more realistic, results in lower performance results.

SanDisk specifications list the Extreme at 550MB/s read and 520MB/s write which seems to be right on the money as we see results of 556MB/s read and 506MB/s write.  Normally, a small fluctuation can be expected and subsequent testing will show results that may be a bit higher or lower.


Crystal Disk Benchmark is used to measure read and write performance through sampling of raw (0/1 Fill/compressible) or random data which is, for the most part, incompressible. Many new SandForce Driven SSD owners who cant wait to test the performance of their SSD often grab this program and run a quick test, not realizing that they are testing with incompressible data rather than compressible data used in testing by manufacturers.  We have provided compressible (oFill) results on the left with incompressible (random data) results on the right.

It is normal for the Crystal Diskmark results on the left to be a bit lower than the previous ATTO results and these tests bring random 4k write results as high as 89MB/s into the picture.  These are nice scores as those low 4k results play a definite role in the visible improvement we see when migrating from a hard drive. As well, these results demonstrate the performance difference when moving highly compressible data, as compared to very incompressible data such as music, movies or photographs.


Up until recently, AS SSD was the only benchmark created specifically for SSD testing and it uses incompressible data.  AS SSD, for the most part, gives us the worst case scenario in SSD transfer speeds while using SandForce Driven SSDs as they use compression in storage as discussed earlier.  Many enthusiasts like to benchmark with AS SSD for their needs.

Our AS SSD results confirm that in which we see above with the Crystal DiskMark result on the right.  The difference between the two can be attributed to the testing configuration of the software, whereas, Crystal DiskMark posts the high of several test passes and AS SSD combines all for an average score.