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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  • juxt417 - Wednesday, April 22, 2015 - link

    Unlike apple. Samsung has a solid reason to not have an SD card. This being that an SD card is too slow to handle 4k content without a lot of lag.
    Ufs 2.0 on the other hand handles 4k just fine. At least from what I have experienced so far.
  • Matthew Sobel - Monday, April 20, 2015 - link

    They make so many smart phones because there are so many markets & carriers and they all want to be special.

    I'm with you on the wish for two branches of the Samsung family tree. Don't forget about the 'Active' variant. There's speculation that this is still coming. If so it may be just what some of us are looking for.
  • FlushedBubblyJock - Friday, April 24, 2015 - link

    The reason you won't get the choice is the constantly complaining crybaby crew has for years whined for an apple rectangle metal box with a brokenback glass rainbow they can selfie with in the mirror and prance around with feeling it up for a "quality industrial design build".
    Then they need it thinner like their figures should be, thinner because a metal clodheaded rectangle with heavy glass is a lead weight, thus paper thin is necessary, as it "gains status for eyebrow lickers".

    See, we call this "the market". The primping faerie overlords knows what's best for their selfish little egos, and thus, you will be made into a dumbed down sheep in compliance with their frivolous vanities.
  • RiotSloth - Thursday, May 14, 2015 - link

    That is the best thing I'm going to read all day. Thank you!
  • Daniel S. Buus - Friday, July 17, 2015 - link

    LOL :'D So much hate :D
  • h3ck - Friday, May 8, 2015 - link

    I agree, the Note 5 will be for the power user and/or business person that wants to "have it all". Where as the Galaxy S line will be consumer friendly and geared toward "ease of use".
  • medi03 - Sunday, April 19, 2015 - link

    That will surely "help" increase sales, right.
  • FlushedBubblyJock - Friday, April 24, 2015 - link

    medi03 - see the finely tuned mind bending the sales crew sells to the clueless primpers>

    "Overall, the design of the Galaxy S6 and S6 edge is really unlike anything else they’ve produced in recent memory. The phone itself is well-sized and feels much more ergonomic than the Galaxy S5 due to the thinner build and mildly reduced bezel size. It really feels like Samsung cared about the design of the phone this generation, and the attention to detail here immediately puts Samsung near the top in this area. "

    Ahh, they "cared" - it feels - even the word ergonomic, when the truth is it's a slippery heavy metal and smoothie glass nightmare ready to crash to the ground... at least the braindead can't "flex it" - the best feature of course is - it's apple clone "quality" for the elite snobs

    Yeah man, that's it bro.
  • edlee - Monday, June 29, 2015 - link

    how did anandtech find out what pvs bin they received, did they check it with a terminal command, and if so, what was that command?
  • Flunk - Friday, April 17, 2015 - link

    I predict that Samsung won't lose any customers because of this. Where are you going to find a modern phone with a removable battery and SD card slot? There just isn't any option anymore. Samsung is trading a few niche features for more mainstream appeal.

    P.S. Samsung will replace the battery for $45, but I imagine that a lot of people reading this site can just swap it themselves.

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