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
POST A COMMENT

306 Comments

View All Comments

  • Inteli - Friday, April 17, 2015 - link

    While no removable battery is workable (if disappointing), I dislike the removal of the SD Card slot in favor of being more iPhone-like, since it allows for more storage (and I don't have to worry about clearing stuff out for updates). Hopefully Samsung won't go this way with the Note 4, or else that might very well be my last Samsung phone. Reply
  • Inteli - Friday, April 17, 2015 - link

    And by Note 4, I meant Note 5. Reply
  • Vandam500 - Friday, April 17, 2015 - link

    I doubt it man. The Note 5 will likely be very similar to the GS6 which means no removable battery and no microSD card slot. Reply
  • mindracer - Friday, April 17, 2015 - link

    I have a feeling Samsung will keep the Note series as it's "productivity/business class", be like the GS6 but with removable storage and battery, and make the GN5 the top of the line in design and features for the real heavy user. Reply
  • Solandri - Friday, April 17, 2015 - link

    What I don't get is, Samsung makes like two dozen different smartphones. Why can't they make two top-tier phones - one with the "everything sealed" philosophy and another with the "user can replace the battery and microSD card" philosophy, both using the same screen, processor, camera, etc.? Reply
  • lyricalsaint - Friday, April 17, 2015 - link

    Probably because Apple has been so successful with marketing theory, and Samsung wants to copy their concept of giving consumers limited choices. Too many choices can put people into somewhat of a decision paralysis. Reply
  • Gigaplex - Friday, April 17, 2015 - link

    But it's too late for that, Samsung already has too many choices. Reply
  • joos2000 - Saturday, April 18, 2015 - link

    It isn't hard to cut models to reduce choice really. They can slim down their product line in months. Reply
  • MacDaddy100 - Friday, April 24, 2015 - link

    It's not a marketing theory, its not many people give a rats a$$ about removable batteries and upgrade memory cards, I plug my phone in at night like 99% of the people do, I have 128gb of internal memory that hold my 10K (High Bit Rate) song library with room left over that very few people even want to do with Pandora and such that don't need the internal memory. Quit living in the 90s, everything thing is online, or in the cloud now. Reply
  • peterfares - Saturday, April 25, 2015 - link

    So then why didn't you just get the 32GB model? Reply

Log in

Don't have an account? Sign up now