Upgrading the SSD in Chromebook & MyDigitalSSD Super Boot Drive M.2 2242 SSD Review
by Kristian Vättö on October 21, 2014 8:00 AM ESTRandom Read/Write Speed
The four corners of SSD performance are as follows: random read, random write, sequential read and sequential write speed. Random accesses are generally small in size, while sequential accesses tend to be larger and thus we have the four Iometer tests we use in all of our reviews.
Our first test writes 4KB in a completely random pattern over an 8GB space of the drive to simulate the sort of random access that you'd see on an OS drive (even this is more stressful than a normal desktop user would see). We perform three concurrent IOs and run the test for 3 minutes. The results reported are in average MB/s over the entire time.
Surprisingly the 16GB Kingston M.2 drive has excellent random read performance. I suspect that having such little NAND helps with random read performance because you are practically hitting the same LBAs, so some IOs may be cached and there is less tracking overhead as well. The MyDigitalSSD drive, on the other hand, does not fare that well, although random read performance has never been the biggest strength of Phison controllers in my experience.
Both the MyDigitalSSD and Kingston drives have rather poor random write performance. Since neither of the drives have a DRAM cache, the host IOs along with the NAND mapping table need to be cached in the internal cache of the controller (or alternatively in NAND), which adds limitations since the internal SRAM caches are typically only a few megabytes in size and NAND is much slower than DRAM.
Sequential Read/Write Speed
To measure sequential performance we run a 1 minute long 128KB sequential test over the entire span of the drive at a queue depth of 1. The results reported are in average MB/s over the entire test length.
Sequential read is also better on the 16GB Kingston drive, so it seems that the additional NAND adds quite a lot of overhead when there is no DRAM for caching purposes. In write speed the MyDigitalSSD drive is considerably faster, although 2.5" 256GB drives are also substantially faster still.
AS-SSD Incompressible Sequential Read/Write Performance
The AS-SSD sequential benchmark uses incompressible data for all of its transfers. The result is a pretty big reduction in sequential write speed on SandForce based controllers, but most other controllers are unaffected.
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nevertell - Tuesday, October 21, 2014 - link
Could you do a review with putting Arch Linux or any other linux distribution and see how well that would fare on a cheap notebook such as this ?Nvidia is claiming to provide proper drivers for their tegra k1 this time around and it might be interesting to see how well a 'desktop' OS would fare on an arm chromebook.
kpb321 - Tuesday, October 21, 2014 - link
I agree. Putting more storage in a Chromebook doesn't make sense for exactly what the article found. The Chrome OS isn't designed around using local storage. Generally, you can't install windows on these machines because their bios doesn't support everything windows needs but ChrUbuntu or Crouton are designed to installed linux on this type of machine and a larger SSD might actually be useful then.danjw - Tuesday, October 21, 2014 - link
For any future M.2 drive reviews, I would suggest you include in the specs grid what the keying is SATA, PCIE or both.BackInAction - Tuesday, October 21, 2014 - link
"Chromebooks are generally the cheapest laptops around, yet if you buy a Windows laptop that costs twice as much you will most likely end up with a traditional hard drive for storage. That is an enormous benefit that Chromebooks have because the lack of a hard drive enables much thinner and lighter designs, which translates into a better user experience."While I believe "better/thinner/lighter" inexpensive windows devices are on their way. This is one of the top benefits of CB over $300 Win laptop. That and the fact that I have no worries about AV and/or software updates.
I own an 2nd gen i3 Win7 desktop, 2nd gen i3 Win7 laptop and a chromebook (Toshiba 13). Until I swapped out the HD on the laptop with a $50 SSD, it was nearly worthless. That said it is still a "tank" compared to the chromebook.
andrewaggb - Tuesday, October 21, 2014 - link
Agreed. I have two first gen I7 laptops and I had to put SSD's in both. Night and day difference. Went from buyers remorse to completely satisfied.LostAlone - Thursday, October 23, 2014 - link
There's obviously fewer worries with a chrome book, but massively reduced functionality too. Chrome books are really awesome for what they are, but is so very hard to recommend them to anyone simply because you don't have the rich application support you have on a full OS. People always seem to think that they browse the web and nothing else, but missing desktop games makes it feels like such a compromise.People need to know for sure that a chrome book will give them exactly what they want when they buy it. That's why it's uptake has stayed so low. Normal human beings aren't so keen because having no local storage and no music player is pretty tough to handle. IT deparments on the other hands go nuts over them because it's the perfect 'work and work alone' kind of machine that is both cheap to replace and with much less scope for things to go wrong.
But in todays world, I'd either spend more and get an MS Surface, or stick with a crappy old laptop because at least I can play Diablo on it.
LoneWolf15 - Tuesday, October 21, 2014 - link
I have used two MyDigitalSSD mSATA drives for some time, a first-gen 128GB and a second-gen 256GB. For anyone concerned about longevity, you needn't be. I got both at release time for each drive, and they are highly reliable. One is in my home theater PC now on an mSATA<->SATA conversion card, and one is in my ThinkPad. At their competitive prices, I'd gladly use them again.Walkop - Tuesday, October 21, 2014 - link
Could the drop in read performance be due to the fact that one of the storage packages within the SSD was filled up before the other…?Dr.Neale - Tuesday, October 21, 2014 - link
Interesting article, illuminates pros and cons of Chrome OS nicely.But I noticed a tiny typo in "Managing Storage in Chrome OS": In the first sentence, the phrase "when it comes file management" should read "when it comes to file management". (Just trying to help to perfect the piece!)
Kristian Vättö - Tuesday, October 21, 2014 - link
Good catch, fixed!