The Mushkin Source 500GB SATA SSD Review: A Value Proposition For An Everyday PC

Working Set Size

DRAMless SSDs may still have a bit of SRAM on the SSD controller to cache a portion of the flash translation layer's mapping tables. Just like a GB of external DRAM can hold the mapping tables for a TB of flash, a few MB of onboard RAM in the controller can hold the mappings for a few GB of flash. We can probe for such a cache by performing random reads with a varying working set size.

Mushkin Source 500GBIntel SSD 545s 512GBSamsung 850 EVO 500GBSamsung 860 PRO 512GBCrucial BX300 480GBPlextor M8V 512GBCrucial MX500 500GBHP S700 500GBADATA Ultimate SU800 512GBADATA XPG SX950 480GBToshiba TR200 480GBOCZ Trion 150 480GB

The Mushkin Source shows some decline in random read performance as the working set size grows beyond just a few GB, but there's no sharp drop in performance like we see with DRAMless NVMe drives that are using the Host Memory Buffer feature. Most of the other drives show roughly the same random read performance regardless of working set size.

Whole-Drive Fill

This test starts with a freshly-erased drive and fills it with 128kB sequential writes at queue depth 32, recording the write speed for each 1GB segment. This test is not representative of any ordinary client/consumer usage pattern, but it does allow us to observe transitions in the drive's behavior as it fills up. This can allow us to estimate the size of any SLC write cache, and get a sense for how much performance remains on the rare occasions where real-world usage keeps writing data after filling the cache.

Mushkin Source 500GBIntel SSD 545s 512GBSamsung 850 EVO 500GBSamsung 860 PRO 512GBCrucial BX300 480GBPlextor M8V 512GBCrucial MX500 500GBHP S700 500GBADATA Ultimate SU800 512GBADATA XPG SX950 480GBToshiba TR200 480GBOCZ Trion 150 480GB

The Mushkin Source lasts a very long time before its SLC cache is filled. While the Toshiba TR200's write speed ends up in the gutter very quickly, it will be almost impossible for a real-world consumer workload to fill the cache of the Source unless the drive starts out nearly full. From an empty drive, the apparent initial SLC cache size is well over 150GB—essentially the entire drive operating as SLC until free space runs out.

Average Throughput for last 16 GB	Overall Average Throughput

In the unlikely event that the SLC write cache on the Mushkin Source should overflow, its sequential write speed drops to the slowest in its class at just over 70 MB/s—slower than most mechanical hard drives. But this is only relevant when writing tens of GB at once.

BAPCo SYSmark 2018

BAPCo's SYSmark 2018 is an application-based benchmark that uses real-world applications to replay usage patterns of business users, with subscores for productivity, creativity and responsiveness. Scores represnt overall system performance and are calibrated against a reference system that is defined to score 1000 in each of the scenarios. A score of, say, 2000, would imply that the system under test is twice as fast as the reference system.

SYSmark scores are based on total application response time as seen by the user, including not only storage latency but time spent by the processor. This means there's a limit to how much a storage improvement could possibly increase scores, because the SSD is only in use for a small fraction of the total test duration. This is a significant difference from our ATSB tests where only the storage portion of the workload is replicated and disk idle times are cut short to a maximum of 25ms.

Our SSD testing with SYSmark uses a different test system than the rest of our SSD tests. This machine is set up to measure total system power consumption rather than just the drive's power.

For the Creativity and Productivity subtests, the Mushkin Source and other DRAMless SSDs offer performance indistinguishable from a mainstream SATA SSD with a DRAM cache; these scenarios are more bottlenecked by CPU power and system RAM. The responsiveness test does reveal some of the reduced performance of DRAMless SSDs, but even so they greatly outperform a mechanical hard drive.

Energy Use

The SYSmark energy use scores measure total system power consumption, excluding the display. Our SYSmark test system idles at around 26 W and peaks at over 60 W measured at the wall during the benchmark run. SATA SSDs seldom exceed 5 W and idle at a fraction of a watt, and the SSDs spend most of the test idle. This means the energy usage scores will inevitably be very close. A typical notebook system will tend to be better optimized for power efficiency than this desktop system, so the SSD would account for a much larger portion of the total and the score difference between SSDs would be more noticeable.

The DRAMless SSDs use a bit less energy during a SYSmark run than the mainstream Crucial MX500, but the HP S700 is the only one that really stands out as saving a non-trivial amount of power, and even in that case the difference is small enough to only matter for low-power notebooks, not our desktop testbed.