Previewing Maxiotek's MK8115 SSD Controller: Can DRAM-less Drives Make The Cut?
by Billy Tallis on May 9, 2017 8:00 AM ESTRandom 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.
As can be expected, the DRAM-less MK8115 drives come in last in the random read speed test, with the MLC drive 13% slower than the OCZ VX500 and MX300 while the MK8115 TLC drive is closer to 28% slower. Samsung's 850 EVO and PRO are both more than twice as fast as the MK8115 drives.
Power consumption during the random read test is reasonable for both MK8115 drives, but the low performance means neither is particularly efficient.
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As queue depths increase both MK8115 samples show moderate increases in performance, tapering off slightly between QD16 and QD32. The MK8115 isn't drawing the most power among SATA SSDs at every single queue depth, but it's close.
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.
Random write speeds of the MK8115 samples are the slowest out of all the drives in this comparison, but the margin is much smaller than for random reads and nowhere near as large as the disparity in steady-state performance. The difference in performance between the MK8115 samples is smaller than it was for random reads.
The MK8115 drive with MLC levels off after QD8. The TLC counterpart was on track to deliver slightly higher performance at significantly lower power consumption, until the TLC drive filled up and the background garbage collection killed performance and drove up power consumption.
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The two MK8115 samples behave rather differently during this random write test. The TLC drive starts out slower at QD1 but performance scales better as queue depth climbs. The TLC drive is also substantially more power efficient, with power consumption growing more slowly than throughput. However, by the end of the test the SLC cache has filled, causing performance to drop below the QD1 throughput and power jumps up to be on par with the MLC drive.
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MajGenRelativity - Tuesday, May 9, 2017 - link
samevladx - Tuesday, May 9, 2017 - link
It will take until Q2 2018 for prices to start going down again.milli - Tuesday, May 9, 2017 - link
You should have included other DRAM-less drives.Billy Tallis - Tuesday, May 9, 2017 - link
I would have, if I had any on hand to test. Nobody's offered one up for review in quite a while, and I've asked a few vendors for a Phison S11 drive but they're not interested.vladx - Tuesday, May 9, 2017 - link
It's pretty obvious why, at least Maxiotek has some guts.bortiz - Tuesday, May 9, 2017 - link
My problem with dram-less ssd is the durability of the drive. How does the life-expectancy of this drive compare to other SSD drives. The DRAM in current SSD drives groups data accesses together, reducing the data array access. This increases performance and array durability. Array durability is proportional to the number of array accesses. I don't think this is a good idea and I would like to see if someone can prove to me that this will have a decent life span (5 years???)vladx - Tuesday, May 9, 2017 - link
Whether a SSD IS DRAM-less or not doesn't influence life expectancy.Billy Tallis - Tuesday, May 9, 2017 - link
SSDs that have external DRAM usually don't use it as a write cache for user data; it's just for caching the mapping metadata. A DRAMless controller like MK8115 can do pretty much the same amount of write combining and wear leveling that a mainstream controller can. There may be a slight increase in write amplification from the controller having to flush metadata updates to the flash more often, but mainstream drives don't want to buffer those writes too much either, for the same safety reasons they don't put user data in the DRAM.Remember that write operations are the only ones that significantly affect drive lifetime. DRAMless controllers need to do more flash reads, but read disturb errors are still too rare for that to matter to drive reliability.
CrazyElf - Tuesday, May 9, 2017 - link
It is difficult for it to make the cut with a low 4k random read and write test like this SSD has.I think that the DRAM cache is well worth it.
I think it is best to hold off on SSDs for now.
rocky12345 - Tuesday, May 9, 2017 - link
Yea no thanks if this is what DRAM-less drives are like I think I will stick to SSD's that can maintain their performance a lot better. I don't care if these drives are a bit cheaper if you end up swearing at your computer because the SSD is lagging then for peace of mind just spend the extra cash on a real SSD.I just sold a gaming system to a customer that had a SSD installed as the windows drive. Yep it booted fast and was pretty peppy but if you tried to work the system it seemed like the SSD would bog right down to a crawl so I would assume it was a DRAM-Less SSD. When I sold the customer on the system I was going off of my own SSD usage on my gaming laptop & gaming desktop options which would never bog down like that. I guess the good news was the customer did come back a few days later and said the system was great and so fast that he never had to wait for stuff to load like he did before on his older setup so he was a happy camper I guess.