NAND Performance: The First UFS Phone

Storage performance is often a critical area for user performance, as applications cannot be cached in RAM at every possible moment. Camera performance is also often limited by storage performance as RAM buffers can only do so much to maintain performance before it’s necessary to commit photos to non-volatile storage.

However due to the memory hierarchy to some extent, storage performance is often hard to notice once it’s at a point where things are “good enough”. Unfortunately, in some cases we can see OEMs failing to include sufficiently performant solid-state storage, which can be a major pain point in the user experience when random read/write performance is low enough that there are noticeable IO pauses as the system has to wait for data to be loaded from storage.

The Samsung Galaxy S6 family is the first shipping implementation of UFS (Universal Flash Storage) 2.0 standard, which makes the internal storage model less like an SD card in nature. When comparing the eMMC 5.1 standard to the UFS 2.0 standard, we see a move from a the 400 MB/s maximum of the eMMC 5.1 standard with HS400 physical link interface to MIPI M-PHY, which allows for a theoretical maximum of around 720 MB/s and should be more efficient in transmitting data than the current eMMC standard. In addition, UFS makes it possible to do full duplex communication, which means that reads and writes can happen simultaneously. There's also a command queue, which helps to avoid inefficiencies that could arise from waiting for commands once a command has been processed by the storage controller, and utilizes the SCSI protocol to facilitate these new features at the interface level.

As for the Galaxy S6 itself, the UFS implementation Samsung is using is Samsung developed. Samsung's current implementation only supports up to 300 MB/s (or 2.4 Gbps) transfer rates as a theoretical maximum, so from an interface perspective it's still not reaching the full capabilities of the standard. Though even at a cap of 300MB/sec, it still stands to be a significant improvement over typical eMMC solutions.

Finally, on a technical note, the 32GB models are of the model KLUBG4G1BD-E0B1 with a maximum queue depth of 16.

In order to test storage performance, we use Androbench with some custom settings to get a reasonable idea of performance in this area, although this test isn’t an exhaustive examination of storage performance by any means.

Internal NAND - Sequential Read

Internal NAND - Sequential Write

Internal NAND - Random Read

Internal NAND - Random Write

The Galaxy S6 performs rather impressively in our standard storage test, but not as fast as one might have hoped. This is due to the nature of the Androbench 3.6 test, which only tests a single IO thread, which won’t use the UFS storage of the Galaxy S6 to its full extent. In order to see the kind of difference that UFS really makes, I ran the same test again on Androbench 4.x, which does support multiple IO threads. However, as our iOS storage test and Androbench 3.6 don’t support more than a single IO thread we will continue to present both results for now.

AndroBench 4.0 - Sequential Read

AndroBench 4.0 - Sequential Write

AndroBench 4.0 - Random Read

AndroBench 4.0 - Random Write

Overall, there are some immense benefits in storage performance here, especially in random IO performance. The Galaxy S6 has some of the fastest storage available in a phone today as far as I can tell given that this is basically a pure MLC solution, and shouldn’t have any real issue with storage performance holding back the rest of the phone over the course of 1-3 years as long as a reasonable amount of free space is kept to allow efficient storage management.

System Performance Cont'd: GPU Performance Camera Architecture and UX
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  • Notmyusualid - Friday, April 17, 2015 - link

    Dead wrong pal - I'm keeping hold of my wireless charging GS5, which includes an SD slot.
  • lilmoe - Friday, April 17, 2015 - link

    They will lose lots of "power users", but they'll conversely gain a couple of orders of magnitude more "casual consumers"...

    Sorry, we power users might have made a significant percentage 2-3 years ago, but now we're a very small minority in the smartphone market, and catering to us via mainstream devices is no longer an option for OEMs...

    The Galaxy Note might have been considered niche 2 years ago, but that's absolutely no longer the case. If a device market is no longer niche, then expect a similar streamlining makeover.
  • FlushedBubblyJock - Friday, April 17, 2015 - link

    You have been catered to. Exactly catered to.
    Whining about the cheap plastic feel, endlessly.

    Now your solution has arrived. If it doesn't come screwed, it won'r feel flimsy and cheap.

    You literally begged for it, for years, as did all your fellow elite power users.
  • Gigaplex - Friday, April 17, 2015 - link

    I use microSD and never whined about plastic. In fact, I would rather plastic than glass any day, regardless of microSD support. Glass just isn't durable.
  • theduckofdeath - Saturday, April 18, 2015 - link

    There will never be a phone that pleases everybody. But the fact that this phone seems to outsell the GS5 by at least 100% is an indication that Samsung made the right choice, with a broader perspective than a single internet commenter's opinion.
  • piiman - Saturday, April 18, 2015 - link

    " But the fact that this phone seems to outsell the GS5 by at least 100% is an indication that Samsung made the right choice, with a broader perspective than a single internet commenter's opinion."

    I doubt your 100% is correct but do you really believe people read that the battery isn't changeable and go "WOW that's the phone for me"? Or "look I can't add memory , whatever that is, so I'm buying it!" Its far more likely they are buying it for its looks and features not lack of.
  • theduckofdeath - Saturday, April 18, 2015 - link

    Like I said, a few loud haters on the internet won't affect the bigger picture. And yes, all the reports are pointing at at least 100% better initial sales than the S5. It's actually "so bad" that Apple seems to be forced back to using the unreliable TSMC as their main supplier of processors, as Samsung can't keep up with the production for their own devices at the moment.
  • FlushedBubblyJock - Friday, April 24, 2015 - link

    " leading at least one Samsung exec to boldly state that the Galaxy S6 and S6 Edge could reach over 70 million units sold. Unfortunately, a new report from Korea indicates that out of the 300,000 pre-orders, only 200,000 units have been sold. This suggests early forecasts may have been inaccurate."

    Yes, 100% theduckofdeath ... totally..
  • FlushedBubblyJock - Friday, April 24, 2015 - link

    Congrats giga - though of course I didn't mean you nor anyone specifically.

    The metal industrial design meme aka apple clone mania is a thing - gotta have the overpriced mazerati right or you just ain't with it...

    One suspects there's a nationwide ban on belittling apple, since it had a massive #1 stock market spot that all the investment channels gloated and blabbed on about - so it's a national security imperative in economic collapse times to only praise apple and demand all others mimic.
    I'd bet the unspoken pressure is enormous.
  • akdj - Sunday, May 31, 2015 - link

    Kinda funny though. Nearly 300 responses and you're the only one droning on and on about 'Apple'. Why? No one's even mentioned Apple -- nor has Apple made a glass phone nearly four years! Lol. Month later ...going through the responses as an owner of the S6, your contributions seems so out of place in this conversation. Kind of like the buddy that's drank a bit too much at the party and won't stop telling everyone how much he loves 'em...

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