Original Link: https://www.anandtech.com/show/8543/upgrading-the-ssd-in-a-chromebook
Upgrading the SSD in Chromebook & MyDigitalSSD Super Boot Drive M.2 2242 SSD Review
by Kristian Vättö on October 21, 2014 8:00 AM EST
While the whole netbook boom kind of died with the introduction of tablets, Chromebooks have been gaining more and more traction recently. The original Windows netbooks failed to provide a smooth user experience due to the lack of operating system optimization, and Windows was simply way too heavy to be run with such limited resources. Chrome OS on the other hand was designed specifically for netbook-like devices. Google took a totally different approach by designing the Chrome OS around web and cloud-based services, which allowed the OS to be run with very little onboard storage.
Most of today's Chromebooks actually ship with either a small mSATA/M.2 SSD or have an eMMC package onboard, which is a bit ironic since 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.
The majority of the Chromebooks have 16GB of onboard storage with some high-end models having twice that. For the intended usage where everything is done in the web, that is sufficient, but when you need local storage for offline occasions (e.g. when traveling), 16GB or 32GB will not get you far. There is always the option of carrying external storage to expand the internal storage, but there is another alternative: upgrading the internal SSD.
For the purpose of this review, MyDigitalSSD sent us a 256GB Super Boot Drive in M.2 2242 form factor along with Acer's C720-2848 Chromebook.
| Acer C720-2848 Chromebook Specifications | |||||||||
| Display | 11.6" 1366x768 | ||||||||
| Processor | Intel Celeron 2955U (2/2, 1.4GHz, 2MB, 15W) | ||||||||
| Graphics | Intel HD Graphics (200MHz, 1GHz max Turbo) | ||||||||
| Memory | 2GB DDR3 | ||||||||
| Storage | 16GB SSD (M.2 2242) | ||||||||
| Connectivity | WiFi (802.11 a/b/g/n), Bluetooth 4.0, 1x USB 3.0, 1x USB 2.0, SD card reader, 1x HDMI | ||||||||
| Dimensions | 11.34" x 8.03" x 0.78" (W x D x H) | ||||||||
| Weight | 2.98lb | ||||||||
The C720 is what you would expect a Chromebook to be. The display is a bad TN panel, the trackpad does not always feel responsive, and the overall build is just plastic. It feels cheap, but the positive thing is that it really is cheap, as the C720-2848 currently retails for just $200. I cannot really give an objective review of the laptop itself as I have not used any other Chromebooks, but overall I am fairly impressed with what $200 gets you nowadays.
| MyDigitalSSD Super Boot Drive M.2 2242 Specifications | |||||||||
| Capacity | 8GB | 16GB | 32GB | 64GB | 128GB | 256GB | |||
| Controller | Phison S9 (PS3109) | ||||||||
| NAND | Toshiba A19nm MLC | ||||||||
| Sequential Read | Up to 545MB/s | ||||||||
| Sequential Write | Up to 410MB/s | ||||||||
| Warranty | Three years | ||||||||
Like other MyDigitalSSD's SSDs, the Super Boot Drive is based on a Phison controller and comes in a variety of capacities. The M.2 2242 currently tops out at 256GB since the form factor limits the number of NAND packages to two, and with 16GB die 128GB packages are the biggest that are available in the open market.
Notice that there is no DRAM at all. The M.2 2242 form factor lacks the space for a dedicated DRAM chip, so the NAND mapping table and host IO caching is done in the internal caches of the controller (usually a few megabytes of SRAM). There is a bit of a performance penalty from doing that as the internal caches are much smaller, but it is the only viable way to squeeze a full SSD into such small area.
Test Systems
There are two major items we want to look at in this review: first, we want to investigate the upgrade procedure for the Acer C720 Chromebook and examine Chrome OS performance, and second we're going to look at the MyDigitalSSD Super Boot Drive as a standard SSD and run our usual storage tests. For AnandTech Storage Benches, performance consistency, random and sequential performance, performance vs. transfer size and load power consumption we use the following system:
| CPU | Intel Core i5-2500K running at 3.3GHz (Turbo & EIST enabled) |
| Motherboard | ASRock Z68 Pro3 |
| Chipset | Intel Z68 |
| Chipset Drivers | Intel 9.1.1.1015 + Intel RST 10.2 |
| Memory | G.Skill RipjawsX DDR3-1600 4 x 8GB (9-9-9-24) |
| Video Card | Palit GeForce GTX 770 JetStream 2GB GDDR5 (1150MHz core clock; 3505MHz GDDR5 effective) |
| Video Drivers | NVIDIA GeForce 332.21 WHQL |
| Desktop Resolution | 1920 x 1080 |
| OS | Windows 7 x64 |
Thanks to G.Skill for the RipjawsX 32GB DDR3 DRAM kit
For slumber power testing we used a different system:
| CPU | Intel Core i7-4770K running at 3.3GHz (Turbo & EIST enabled, C-states disabled) |
| Motherboard | ASUS Z87 Deluxe (BIOS 1707) |
| Chipset | Intel Z87 |
| Chipset Drivers | Intel 9.4.0.1026 + Intel RST 12.9 |
| Memory | Corsair Vengeance DDR3-1866 2x8GB (9-10-9-27 2T) |
| Graphics | Intel HD Graphics 4600 |
| Graphics Drivers | 15.33.8.64.3345 |
| Desktop Resolution | 1920 x 1080 |
| OS | Windows 7 x64 |
- Thanks to Intel for the Core i7-4770K CPU
- Thanks to ASUS for the Z87 Deluxe motherboard
- Thanks to Corsair for the Vengeance 16GB DDR3-1866 DRAM kit, RM750 power supply, Hydro H60 CPU cooler and Carbide 330R case
The Upgrade
Upgrading the storage in the Acer C720 Chromebook is surprisingly easy. While Chrome OS does not give the user full system access, there is an integrated (albeit hidden) tool for creating recovery media that can be used to clone the old drive. To open the tool, all you need to do is to open Chrome (i.e. the web browser) and type "chrome://imageburner" to the address bar. Once you have done that, you should see the following:
To create the recovery media, you need either a USB drive or an SD card (minimum 4GB). The tool will not just clone your existing drive but will in fact download the OS again, which in my case was a 498MB download. The downloaded file is then extracted to the USB drive to create the bootable recovery media.
Alternatively, you can also create the recovery media using another computer. Google offers a tool for both Windows and OS X, which can be found here along with the instructions. I tried this as well on my Mac Pro and did not encounter any issues.
After successfully creating the recovery media, you can begin the actual upgrade, which starts by removing the 13 screws on the bottom of the laptop.
Note that at least in the case of the Acer C720, the warranty is (in theory) void if you remove the back cover. That is unfortunate, but on the other hand Chromebooks have not been designed to be user upgradeable.
This is what the internals of the C720 look like. The SSD is located on the right-hand side right above the speaker, so upgrading it does not involve any further disassembly.
The C720 ships with a 16GB Kingston SSD that is held in place by a single screw. Simply remove the screw and the SSD will come out of its socket.
The Kingston SSD is also Phison S9 based and has a single 16GB NAND package with Kingston markings on it. I apologize for the unclear package markings – the label left residue on the packages, which made the markings practically invisible. Anyway, Kingston has not published any NAND data sheets so the markings would not give us many details in the first place. I would make an educated guess that the NAND package has two 64Gbit dies in it from either Micron or Toshiba.
Installing the new SSD is as easy as removing the old one and the assembly process also follows the same instructions as the disassembly, just in the opposite order.
With the new SSD installed, you need to boot with the USB drive or SD card attached for the recovery process to start. Otherwise you will be presented a message that says no OS found and asks you to insert the recovery media or create one using another computer.
The recovery process itself only takes about 15 minutes, so the whole upgrade process should take around half an hour or so. Once the recovery process is complete, the system will be ready for use. The nice thing about Chrome OS is that because it is cloud based, signing in to your Google account will basically restore all settings that you had in place previously, so you can continue from where you were before the upgrade.
Managing Storage in Chrome OS
Chrome OS behaves a lot like iOS and Android when it comes to file management. While other computer-level operating systems like Windows and OS X give the user full access to system files, Chrome OS only provides very basic file management options.
The user access is limited to 'Google Drive' and 'Downloads' folders, and out of these two Downloads is the only truly local folder since Google Drive relies on cloud storage (although it does have offline functionality too). There is no way to create additional folders (or at least I could not find a way), so if you want to store something locally, it must be stored in the Downloads folder.
The 16GB SSD has about 9.7GB left with the operating system installed, so there is certainly not much room for offline storage in the default configuration. With the 256GB SSD installed, the free space increases to about 204GB, although I am not sure where the remaining ~46GB has gone.
Fortunately, it is possible to create folders inside the Downloads folder, so you can at least have some level of organization for local files. Chrome OS has integrated audio and video playback software (even MKV files are supported!) that can be used to play back local files, but especially the audio player is very limited and does not have support for playlists or other more sophisticated features. It works, but the user experience is much better if you have an Internet connection and use Google's web-based Play Music.
Anyway, there is not much to say about Chrome OS' file management. It is very limited and not user friendly for someone who is used to using Windows or OS X, but if you can work around the limitations it can be usable even with a larger internal drive. As far as performance testing under Chrome OS, there isn't much to be done; the MyDigitalSSD Super Boot Drive feels a bit faster on some tasks, but Chrome OS doesn't tend to hit storage much so the performance benefits aren't the primary reason to upgrade. But let's look at performance with the original and upgrade SSDs using our standard storage tests.
Performance Consistency
Performance consistency tells us a lot about the architecture of these SSDs and how they handle internal fragmentation. The reason we do not have consistent IO latency with SSDs is because inevitably all controllers have to do some amount of defragmentation or garbage collection in order to continue operating at high speeds. When and how an SSD decides to run its defrag or cleanup routines directly impacts the user experience as inconsistent performance results in application slowdowns.
To test IO consistency, we fill a secure erased SSD with sequential data to ensure that all user accessible LBAs (Logical Block Addresses) have data associated with them. Next we kick off a 4KB random write workload across all LBAs at a queue depth of 32 using incompressible data. The test is run for just over half an hour and we record instantaneous IOPS every second.
We are also testing drives with added over-provisioning by limiting the LBA range. This gives us a look into the drive’s behavior with varying levels of empty space, which is frankly a more realistic approach for client workloads.
Each of the three graphs has its own purpose. The first one is of the whole duration of the test in log scale. The second and third one zoom into the beginning of steady-state operation (t=1400s) but on different scales: the second one uses log scale for easy comparison whereas the third one uses linear scale for better visualization of differences between drives. Click the dropdown selections below each graph to switch the source data.
For more detailed description of the test and why performance consistency matters, read our original Intel SSD DC S3700 article.
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| Default | |||||||||
| 25% Over-Provisioning | |||||||||
Performance consistency is not very good, but that was expected as we are dealing with a DRAM-less design. With insufficient cache for the NAND mapping table, it is very hard to manage the table efficiently in the steady-state environment, which results in decreased performance. The good news is that Chrome OS is extremely light and a scenario like this is basically impossible, so the data here is merely an interesting piece of information.
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| Default | |||||||||
| 25% Over-Provisioning | |||||||||
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| Default | |||||||||
| 25% Over-Provisioning | |||||||||
TRIM Validation
To test TRIM, I filled the drive with sequential 128KB data and proceeded with a 30-minute random 4KB write (QD32) workload to put the drive into steady-state. After that I TRIM'ed the drive by issuing a quick format in Windows and ran HD Tach to produce the graph below.
It seems that TRIM is working, although there is an odd drop in read performance after the ~140GB mark.
AnandTech Storage Bench 2013
Our Storage Bench 2013 focuses on worst-case multitasking and IO consistency. Similar to our earlier Storage Benches, the test is still application trace based – we record all IO requests made to a test system and play them back on the drive we are testing and run statistical analysis on the drive's responses. There are 49.8 million IO operations in total with 1583.0GB of reads and 875.6GB of writes. I'm not including the full description of the test for better readability, so make sure to read our Storage Bench 2013 introduction for the full details.
| AnandTech Storage Bench 2013 - The Destroyer | ||
| Workload | Description | Applications Used |
| Photo Sync/Editing | Import images, edit, export | Adobe Photoshop CS6, Adobe Lightroom 4, Dropbox |
| Gaming | Download/install games, play games | Steam, Deus Ex, Skyrim, StarCraft 2, BioShock Infinite |
| Virtualization | Run/manage VM, use general apps inside VM | VirtualBox |
| General Productivity | Browse the web, manage local email, copy files, encrypt/decrypt files, backup system, download content, virus/malware scan | Chrome, IE10, Outlook, Windows 8, AxCrypt, uTorrent, Ad-Aware |
| Video Playback | Copy and watch movies | Windows 8 |
| Application Development | Compile projects, check out code, download code samples | Visual Studio 2012 |
We are reporting two primary metrics with the Destroyer: average data rate in MB/s and average service time in microseconds. The former gives you an idea of the throughput of the drive during the time that it was running the test workload. This can be a very good indication of overall performance. What average data rate doesn't do a good job of is taking into account response time of very bursty (read: high queue depth) IO. By reporting average service time we heavily weigh latency for queued IOs. You'll note that this is a metric we have been reporting in our enterprise benchmarks for a while now. With the client tests maturing, the time was right for a little convergence.
The Super Boot Drive actually does surprisingly well in our 2013 suite given that it is an M.2 2242 design while the other SSDs in the comparison are 2.5". The M.2 2242 form factor does not allow for a separate DRAM cache and limits the drive to just two channels, leaving half the channels unpopulated and thus reducing maximum performance.
AnandTech Storage Bench 2011
Back in 2011 (which seems like so long ago now!), we introduced our AnandTech Storage Bench, a suite of benchmarks that took traces of real OS/application usage and played them back in a repeatable manner. The MOASB, officially called AnandTech Storage Bench 2011 – Heavy Workload, mainly focuses on peak IO performance and basic garbage collection routines. There is a lot of downloading and application installing that happens during the course of this test. Our thinking was that it's during application installs, file copies, downloading and multitasking with all of this that you can really notice performance differences between drives. The full description of the Heavy test can be found here, while the Light workload details are here.
In our 2011 Storage Benches the performance is not as good, though. It seems that the limited channel count is not that much of a bottleneck in worst-case scenario, but it certainly limits the peak performance as we can see here. However, I also included the 16GB Kingston M.2 that came in the Chromebook for comparison and the performance difference is tremendous.
Random 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.
Performance vs. Transfer Size
ATTO is a useful tool for quickly benchmarking performance across various transfer sizes. You can get the complete data set in Bench. I must say that something does not add up here because even the 16GB Kingston drive shows performance of ~400MB/s in write speed, whereas our Iometer tests showed that the drive can barely push 25MB/s in sequential write. I have never been a big fan of ATTO, but this further proves that it might be better for us to migrate everything to Iometer for our 2015 suite (yes, there is one in the works!).
Click for full size
Power Consumption
Both the MyDigitalSSD and Kingston drive have excellent power characteristics. The lack of DRAM enables lower power consumption and the limited number of NAND channels further helps to keep the power consumption low. The Kingston 16GB SSD is lower power overall, but for idle workloads the difference is going to be negligible in terms of battery life.
Final Words
Let's start with a conclusion of the Chromebook SSD upgrade before we move on to the actual drive. The positive news is that the upgrade process itself has been made relatively simple and effortless. With the built-in recovery tool the migration is easy and even the physical upgrade is only a matter of removing a handful of screws (although this may depend on what Chromebook you have). Compared to a Windows laptop, I would say the upgrade is easier as you do not need third party cloning software and the whole process takes less time.
Unfortunately, the good news mostly ends here. Because Chrome OS is designed for a web/cloud environment, it does not play nice with local storage. While you can technically have some level of file management inside the downloads folder, it is a compromise and the user experience is far from good. There is no proper music player for instance, so you are limited to using the Files app (a Chrome OS take on the Windows Explorer) for song selection, which works but is nowhere near as convenient as using Windows Media Player or iTunes for playback with support for playlists and other common features. The experience just feels incomplete if you are used to using Windows or OS X because of the limited functionality.
Moreover, at least in the case of our Acer C720 Chromebook the warranty will be voided if the SSD is upgraded. If you have an older Chromebook that is already out of warranty anyway, that is not an issue, but I would not recommend buying a Chromebook with an SSD upgrade in mind if the warranty has any value to you.
| Capacity | 32GB | 64GB | 128GB | 256GB |
| MyDigitalSSD Super Boot Drive M.2 2242 | $33 | $45 | $79 | $170 |
| Transcend MTS400 M.2 2242 | $40 | $50 | $77 | $135 |
EDIT: MyDigitalSSD also offers a cheaper Super Boot Eco drive with Micron NAND in up to 128GB capacity.
The third issue is price. Ultimately the number one selling point of Chromebooks is the low price, so it does not make all that much sense to spend ~$200 on the Chromebook and then fork out another $170 for the SSD upgrade. The 256GB is not the only available capacity, though, and the smaller capacities are cheaper, but to be honest it just makes more sense to buy a USB drive or an SD card for offline media storage since they are generally cheaper. You will also get to keep your warranty and external storage can be used with other devices as well.
Obviously, Chromebooks are not the only market for M.2 2242 SSDs. As the PC industry migrates from mSATA to M.2, we will see more and more designs using the M.2 2242 form factor for space savings. While the MyDigitalSSD Super Boot Drive is fairly slow by today's standards, it is one of the only M.2 2242 retail SSDs available (with the Transcend MTS400 being the only other drive that I could find). Then again, the laptops that use M.2 2242 SSDs are usually not high-end in the first place, so for light use both the MyDigitalSSD and Transcend drives should be fine.
All in all, MyDigitalSSD's Super Boot Drive gives Chromebook users an option to upgrade the internal storage for those who need it. I do not think the market is big, though, because you will have to live with the Chrome OS limitations, but someone who likes to carry around more than just a handful of HD movies might see the value in the upgrade. Long-term, it's also worth noting that Chrome OS sees regular updates, so it's entirely possible we'll see a future release add features and functionality that improve the offline storage experience. However, until that happens the benefits of upgrading the internal storage are pretty limited.
As far as the MyDigitalSSD Super Boot Drive goes, performance is on the low end of the spectrum. That comes from the constraints discussed above (i.e. the M.2 2242 form factor). It's still substantially faster than a typical hard drive, and the power characteristics are good as well, but there aren't many use cases for M.2 2242 right now – most laptops support the larger M.2 2260 and 2280 form factors, which can offer higher performance among other benefits, not to mention 2.5" drives. The MyDigitalSSD Super Boot Drive and Transcend MTS400 are pretty much it if you need a 2242 size SSD, but they're not price competitive with larger 2.5" SSDs so there are better options for most users.
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