JMicron Returns: The JMF667H Controller On Four Reference SSDs

Results: Tom's Hardware Storage Bench v1.0, Continued

Service Times

Beyond the average data rate reported on the previous page, there's even more information we can collect from Tom's Hardware's Storage Bench. For instance, mean (average) service times show what responsiveness is like on an average I/O during the trace.

It would be difficult to graph the 10+ million I/Os that make up our test, so looking at the average time to service an I/O makes more sense. For a more nuanced idea of what's transpiring during the trace, we plot mean service times for reads against writes. That way, drives with better latency show up closer to the origin; lower numbers are better.

Write service time is simply the total time it takes an input or output operation to be issued by the host operating system, travel to the storage subsystem, commit to the device, and have the drive acknowledge the operation. Read service is similar. The operating system asks the storage device for data in a certain location, the SSD reads that information, and then sends it to the host. Modern computers are fast and SSDs are zippy, but there's still a significant amount of latency involved in a storage transaction.

As you look through the results, note that any time we get four capacities from the same product family, it's not uncommon for there to be a big delta between the smallest and largest models.

And indeed, the spread is more significant than I would have expected given two capacities and different NAND interfaces.

Mean Read Service Time

By now, we've come to expect the L85A/L85C-equipped configs pulling up the rear. On the other hand, the reference JMF667H-based SSDs with Toggle-mode NAND look hot. Both capacities are split by the M5 Pro, and they finish ahead of Adata's zippy SP920 at 512 GB.

Those read service times are only slightly related to capacity though, whereas write service times correlate more closely.

JMicron's L85C-based 128 GB drive beats out the 120 GB M500, while the 128 GB JMicron drive with A19 flash falls behind Silicon Motion's reference platform by a slim 11-microsecond average.

Create a new thread in the US Reviews comments forum about this subject
This thread is closed for comments
Comment from the forums
    Your comment
  • blackmagnum
    JMicron vs. Silicon Motion: Fight of the Underdogs - Coming next issue!
  • Snipergod87
    Page 6: "For every 1 GB the host asked to be written, Mushkin's drive is forced to write 1.05 GB."

    Mushkin drive?, To much copy paste.
  • koolkei
    guys. please take a look at this

    that's an actual SSD using this controller, and the price is........ a little more than surprising...
  • pjmelect
    I remember their USB to IDE SATA chip. It caused data corruption every 4 GB or so when transferring data via the IDE interface. I have always been wary of their products since then.
  • tripleX
    "But we're not going to use theoretical corner cases (the sequential and random 4 KB benchmarks we just ran) to crown one configuration a winner and another a loser."

    A corner case is not sequential and random benchmarks. It is an engineering term that means, according to Wiki:

    A corner case (or pathological case) is a problem or situation that occurs only outside of normal operating parameters—specifically one that manifests itself when multiple environmental variables or conditions are simultaneously at extreme levels, even though each parameter is within the specified range for that parameter.
  • g00ey
    JMicron has always made pretty shitty products so I won´'t buy any of these anytime soon...
  • 2Be_or_Not2Be
    I, too, find it hard to want to purchase a drive from a manufacturer with such a lackluster history.

    One part of this article that also doesn't make sense: "Why four channels and not eight? Efficiency is one key motivator. Fewer channels facilitate a smaller ASIC, which can, in turn, be more power-friendly." Compare the size of the PCB to one like the Samsung 850 Pro. They aren't saving much in real estate (they are actually bigger than the Samsung boards), so it makes it hard to believe they're saving much in power here.
  • biohazard918
    Jmicron returns: this time its personal!
  • gsxrme
    No Mushkin Chronos!? Wa we don't want to make Samsungs butt hurt? Com'on Toms!