Random Read Performance

The random read test requests 4kB blocks and tests queue depths ranging from 1 to 32. The queue depth is doubled every three minutes, for a total test duration of 18 minutes. The test spans the entire drive, which is filled before the test starts. The primary score we report is an average of performances at queue depths 1, 2 and 4, as client usage typically consists mostly of low queue depth operations.

Iometer - 4KB Random Read

The SP550's random read performance is slightly higher than most of the TLC-based competition, but significantly slower than the SM2256 prototype with Samsung 19nm TLC managed. There's still a clear gap between the MLC drives and most of the TLC drives. The Samsung 850 EVO and SanDisk Ultra II are still the only TLC drives that can compete against MLC.

Iometer - 4KB Random Read (Power)

The SP550's power consumption is about average. TLC flash usually only has a slight disadvantage for read power and Silicon Motion's very efficient controller offsets that for the SP550.

Looking at performance over various queue depths, all three capacities of the SP550 perform very similarly at low depths, with performance that starts quite low and doesn't increase very steeply. At higher queue depths the 120GB SP550 isn't able to scale up performance as much as the larger capacities, and even the 480GB model can't crack 300MB/s while high-end SATA drives top out around 400MB/s.

Random Write Performance

The random write test writes 4kB blocks and tests queue depths ranging from 1 to 32. The queue depth is doubled every three minutes, for a total test duration of 18 minutes. The test is limited to a 16GB portion of the drive, and the drive is empty save for the 16GB test file. The primary score we report is an average of performances at queue depths 1, 2 and 4, as client usage typically consists mostly of low queue depth operations.

Iometer - 4KB Random Write

Random write performance is the SP550's biggest weakness. It beats the Crucial BX200 at equivalent capacities, but falls well behind everything else. While the steady-state random write performance was relatively good, this performance on this shorter test does not impress.

Iometer - 4KB Random Write (Power)

The power consumption of the SP550 on the random write test is very good, but given the bad performance there's no efficiency advantage.

The SP550's random write speed doesn't scale much with queue depth. Fortunately, neither does the power consumption—a welcome change from the Crucial BX200. The OCZ Trion 100 and Toshiba Q300 also don't scale, but everything else does to at least some extent, including the SM2256 prototype.

AnandTech Storage Bench - Light Sequential Performance


View All Comments

  • tipoo - Wednesday, March 23, 2016 - link

    I never really thought about core counts in storage controllers before this review. What would your average mid range and high end SSDs have for controller CPUs?

    I think I also remember looking into this model for a cheap old laptop upgrade, but some reviews mentioned it didn't have a DRAM cache which made performance consistency very not consistent. That looks similar here in the charts, is this the one with no DRAM?
  • vladx - Wednesday, March 23, 2016 - link

    Most SSD controllers use dual or tri-core ARM Cortex-R4 configurations. Reply
  • MrCommunistGen - Wednesday, March 23, 2016 - link

    The 2TB 850Pro/EVO article here on Anandtech has a table showing core counts and clock speeds of the recent Samsung SSD controllers: MDX, MEX, MGX, MHX, all of which are 3-core ARM Cortex R4 except for the MGX which is a dual core ARM Cortex R4.

    The breakdown is a bit complex but it looks like MDX is 840/840 Pro. MEX is 840 EVO, 128-1TB 850 Pro, and 1TB 850 EVO. MGX is 120-500GB 850 EVO, and MHX is in the 2TB 850 Pro/EVO.

    Going through historical articles (840 Pro review) I found that the Samsung 830's controller was called the MCX and it is implied but not directly stated that it was a 3-core ARM9 design.

    Not to toot my own horn, but the "Update" in the 840 Pro article regarding MDX being R4 rather than ARM9 was at least partially due to an email chain I had with Anand. Yes, I emailed him instead of blasting him in the comments section. As I recall, he said the original press kit had said ARM9. I'd seen Cortex-R4 elsewhere on the 'net, and Anand reached out to Samsung for confirmation. I assume he got it because he updated the article later that day.

    I don't remember seeing much info on core counts for other controllers, but the 840 Pro article also has a table where it notes DRAM Size for various controllers of the time. What's notable to me is that the old Intel controllers like in the X25M G2 didn't cache user data, only the mapping tables, so the G3 is listed in the table as using up to 64MB cache.

    Also notable is that the SandForce controllers didn't use a DRAM cache - probably a large part of their huge industry success, in addition to their (at the time) class leading performance, and the fact that they sold turn-key solutions to OEMs.
  • Billy Tallis - Wednesday, March 23, 2016 - link

    The SP550 uses Samsung DRAM. Silicon Motion does have a controller designed for DRAM-less MLC drives, but their controllers for TLC SSDs all still have a DRAM controller. I've been told that it's theoretically possible to use SM2256 or SM2258 without external DRAM, but I don't know if anyone has actually written the firmware necessary to accomplish that. The performance hit of operating without external DRAM is so far something that is usually only acceptable for USB drives, not mass-market SATA SSDs. Reply
  • hojnikb - Wednesday, March 23, 2016 - link

    Well, sandforce and sm246xt perform just fine without dram Reply
  • ghanz - Wednesday, March 23, 2016 - link

    In general, they perform fine for light & general user scenarios, but IOPS suffers.
    In SM2246XT product brief, random reads are quoted at 28,000 IOPS & random Write at 65,000 IOPS (120GB SSD with Toshiba 19nm MLC).

    Both Sandforce & SM2246XT are only used with MLC NAND since they were not design to work with TLC ones.
    The IOPS drop on a theoretical SSD controller without external dram & working with TLC NAND will be much worse I presume.
  • Samus - Wednesday, March 30, 2016 - link

    Any TLC platform without DRAM or an SLC caching mechanism is going to burn out the NAND; the wear leveling will be off the wall. Reply
  • Pizzahut23 - Wednesday, March 23, 2016 - link

    Are we going to get a review of the phison PNY cs2211? It was recommend last month on the recommend budget SSD list. How does it compare to the legendary bx100 which is about the same price? Is it the new go to budget SSD? Reply
  • Billy Tallis - Wednesday, March 23, 2016 - link

    I've tested both the PNY CS1311 and CS2211. They won't be the next review I post, but probably the one after that. As compared to the BX100, the CS2211 is very broadly in the same performance class, but its different controller architecture means it has very different strengths and weaknesses. Reply
  • ghanz - Wednesday, March 23, 2016 - link

    Hi Billy, are there any plans to review the Sandisk Plus 240gb or/& 480gb?
    It's probably cheapest MLC drive in lower capacities now I believe.
    While it's similar to the Sandisk extreme 500, it will be interesting to see the differences of the same SM2246XT controller on a SATA3 interface instead of USB 3.0/3.1.
    It will also be interesting to compare a budget MLC drive with the influx of recent budget TLC drives.

Log in

Don't have an account? Sign up now