The Samsung SSD 850 120GB Review: A Little TLC for SATA

Mixed Random Performance

Our test of mixed random reads and writes covers mixes varying from pure reads to pure writes at 10% increments. Each mix is tested for up to 1 minute or 32GB of data transferred. The test is conducted with a queue depth of 4, and is limited to a 64GB span of the drive. In between each mix, the drive is given idle time of up to one minute so that the overall duty cycle is 50%.

The mixed random I/O performance of the Samsung SSD 850 120GB is substantially slower than the old 850 EVO, but is slightly faster than the 750 EVO and well ahead of all the non-Samsung drives.

Samsung SSD 850 120GBADATA Premier SP550 120GBADATA Ultimate SU800 128GBADATA XPG SX930 120GBHP S700 120GBHP S700 Pro 128GBPNY CS1311 120GBSamsung 750 EVO 120GBSamsung 850 PRO 128GBSamsung 850 EVO 120GB

The 850 120GB isn't particularly consistent across the mixed random I/O test, and there isn't a strong trend to its performance. It is somewhat slower on the write-heavy half of the test. It is slower than the old 850 EVO in every phase of the test and doesn't significantly pick up the pace at the end when the workload is almost pure random writes, but neither does it suffer any severe performance drops.

Mixed Sequential Performance

Our test of mixed sequential reads and writes differs from the mixed random I/O test by performing 128kB sequential accesses rather than 4kB accesses at random locations, and the sequential test is conducted at queue depth 1. The range of mixes tested is the same, and the timing and limits on data transfers are also the same as above.

The Samsung drives are the four fastest drives on the mixed sequential workload test, with the 850 120GB coming in third place of the 120-128GB drives and only slightly faster than the 750 EVO. The 850 120GB is about 30% faster than the HP S700, the next fastest in-production model in this roundup.

Samsung SSD 850 120GBADATA Premier SP550 120GBADATA Ultimate SU800 128GBADATA XPG SX930 120GBHP S700 120GBHP S700 Pro 128GBPNY CS1311 120GBSamsung 750 EVO 120GBSamsung 850 PRO 128GBSamsung 850 EVO 120GB

The performance of the Samsung SSD 850 120GB drops significantly during the first half of the mixed sequential I/O test as the proportion of writes increases, but it stabilizes in the second half of the test. The other Samsung drives are the only ones that meaningfully outperform the 850 120GB at any point during the test,
but the 850 PRO is the only one that maintains a clear lead over the 850 120GB all the way through.