Android 7.0: What are seamless updates and how do they work?

One of the coolest features Google showed off at Google I/O 2016 that will be part of Android 7.0 Nougat are seamless updates. While it's not going to be flashy or have much to show on the user-facing side, the details on how it's done are interesting, and actually so simple you wonder why it took so long to happen.

Let's have a look.

What are Seamless Updates?

The way Android updates work up to Marshmallow involves some user interaction and takes plenty of time. You get a notification that there's an update waiting for you, and when you say OK it begins to download. Once you get everything downloaded, the one big file unpacks itself in the cache partition and the system checks the integrity of all the individual image files to make sure they are all signed with the correct key and came from the right place. You're then prompted to reboot, but not into Android.

You end up in the device's recovery software where the images are flashed to the correct places on your phone's internal storage. This takes a fairly long time because of the way the files are copied and moved — it's a bit-by-bit transfer. The files actually are moved to memory in chunks, erased from their original position and rewritten to the new position. This is the best way to make sure nothing gets corrupted while it's being installed.

With Android N your phone can be updated like a Chromebook while you're still using it

Once everything is in place, your phone reboots and you wait for the runtime component to look through the system and "upgrade" your apps to the latest version. What it's doing is optimizing the apps for the specific version of the Android runtime. Android apps don't run from the single file you download and install, and are pre-compiled into odex files. That way apps can load faster and the boot process (not counting the first boot after and update) will be much faster.

Then you get to use your phone again.

While most of the time for most people the 10 to 15 minutes it takes to upgrade your operating system doesn't cause too much trouble, any way that can minimize downtime is a better way. Your phone should be available in case of an emergency whenever you need or want it to be available. Enter seamless updates.

With Android 7.0 Nougat, your phone can (not will — more on that later) update like Chrome OS updates. All the downloading and copying of files is done in the background while you're using your phone, and once it's finished you will be notified that your system will upgrade the next time you reboot your phone. And changes to the runtime compiler mean that you won't have to sit through the process of updating all of your apps when you reboot.

That sounds cool — how does it work?

Seamless updates work by having two different system partitions on your phone. When using a phone that can perform seamless updates, all the unpacking and transferring is done while one system partition is running, and things are copied and moved into the second partition. The way Android is divided into individual partitions means the data portion — where all the information you've entered about an app, things like address books or settings or game save progress — are stored in a separate spot outside of the place where the actual system files live. This is good for system security (the data partition can have its own set of file and folder permissions) and it makes things pretty convenient for seamless updates.

Two system partitions means more space will be used.

Once all this is done, you can reboot and use the new system partition. This is done without moving the partitions or renaming them because they are numbered. A configuration file used during the boot process (equivalent to /etc/fstab for the Linux nerds in the house) is read that tells the kernel and boot process where each partition starts and stops. This file is changed to point to the new system partition instead of the current one. The next time you update, the other system partition will be wiped and used. They swap back and forth seamlessly.

This isn't new. If you have the Chrome browser on your computer or have a Chromebook, this is exactly how those systems or apps update. But it's new for Android and does two things. It keeps you from having too much downtime (and there are plenty of folks who will dismiss an upgrade notification because they don't want to fool with the current process). And it is better for security because it can happen automatically when you reboot your phone.

Other important stuff to know

N security

  • Seamless updates aren't a requirement for manufacturers. Your existing phone isn't partitioned correctly and won't be able to perform seamless updates. And you don't want a future update to try and repartition it — the internal memory was designed to have its record (a map of where each partition lives) written once and never changed. That means the people who make your next phone might not use the seamless update feature because they don't have to. We know that the 2016 Nexus phones will have it enabled, but nothing beyond that.
  • There should be some opt-out settings so the process isn't automated if you don't want it to be. I don't have the full details but I was assured by Google that there will be a setting of some sort. This won't be a Windows 10 style fiasco. We'll find it and tell you where to look as soon as we have a phone that uses it in our hot little hands.
  • This will use more space on your phone's internal storage. It uses a complete second system partition. Expect a couple of gigabytes to be used and reserved for it.

This is just one of the many great under-the-hood improvements that come with Android 7.0 Nougat. We'll talk more about the changes and what to expect in future instalments of this series, and you can head into the forums to discuss it all.

Jerry Hildenbrand
Senior Editor — Google Ecosystem

Jerry is an amateur woodworker and struggling shade tree mechanic. There's nothing he can't take apart, but many things he can't reassemble. You'll find him writing and speaking his loud opinion on Android Central and occasionally on Twitter.

  • Will this work if you are rooted with a different recovery? Posted via the Android Central App
  • Doubtful since you can't get autoupdates with TWRP as it stands.
  • Many CM-based ROMS allow auto-updates with TWRP.
  • OK. I was thinking Google, Samsung, HTC and the rest running their specific "stock" roms. But .. fair enough.
  • No; it won't. Part of the process is verifying the digital signature of both sets of files. With a custom recovery, the process will stop as soon as it realizes it isn't the stock recovery and/or bootloader associated with that build number.
  • I didn't know that successive updates would alternate system partitions. Cool, but it sounds like one more thing for first-time rooters to stay the hell away from. Or will those partitions be especially tough to access?
  • So what happens with an older Nexus? Will my Nexus 6 be updated to take advantage of this new feature? Since it's a Google product I'm thinking and hoping that Google can find a way to modify my partitions to take advantage of this feature when it delivers 7.0... Posted via Nexus 6
  • There's no way to modify the system partition without the phone being hooked up to a computer in fastboot mode. And if something goes wrong during the re-partitioning, your phone is now a brick. This isn't going to happen to older phones.
  • What if I wipe my 6P and flash it with a Nougat factory image? You would think that should work unless Google specifically chooses to not support it for the older Nexus devices. I've seen all the partitions get created when you flash a factory image so there's no reason why they couldn't set up the needed partitions then.
  • You're not re-partioning the phone at that point, you're wiping the old partitions and writing into them. It's a different process, and I don't think they're going to bother making it work on current devices.
  • Well this sucks if true since security updates are monthly. This would have been so convenient. Still hoping that Google will find a way to support it's Nexus devices at least. Posted via Nexus 6
  • I agree. I don't see why it would be so hard. I get that you can't resize existing partitions easily when there is already data in them. But if I'm wiping out my old partitions and creating new ones, I don't see why they wouldn't just create the extra one needed for silent updating.
  • The people who manufacture the flash memory recommend you don't change that record on the media once it has been set. The bootloader and radio/modem partitions are not write protected. It would be easy for a program like parted to accidentally write to them while swapping large blocks in and out of place (the phone is then bricked forever). Repartitioning a block device is different than a computer hard drive. The process is very prone to failure, and any mistake would leave you with a brick. Doing it is easy. You just use the parted tool compiled for ARM and run it as normal with elevated permissions. The problems arise when something goes wrong, and things go wrong at a pretty high rate.
  • Jerry, since when is a computer hard drive not a block device? Both HDD and SDDs are block devices. Posted via the Android Central App
  • Yes -- computer hard drives are definitely block devices (a device that supports data reading/writing in blocks, sectors, or clusters). Partitioning your phone's storage is no different than partitioning any other block device. The tools available may not be as robust as ones on a PC because the consumer generally has no need to change the partitioning of a phone. When you flash a factory image on a Nexus device, you can see it create the partitions it needs. I don't see why it couldn't create the new partition needed for silent updating on older Nexus devices.
  • Besides the new Nexus devices,will the LG V20 be configured properly for this system? Posted via the Android Central App
  • We won't know until the announce it one way or another
  • Great. Except most Android phones never get an updated OS anyway, so what's the point?
  • U salty
  • Wow Such Cringe Very Salty. Posted via the Android Central App
    for LG G3
  • Agreed 100% Posted via the Android Central App
  • This is about the future, but I agree 100% with you.
    But assume the life cycle of most devices is 2-3 years 2019 all Android phones will have Nougat at least and the seamless updates...
    Didnt windows phones sort of work this way? Man I miss my windows phone...still have all of them, and with them off they still have the same amount of apps available to me as it is when it is on...mostly none... Posted via the Android Central App
  • While that's true, it only matters if non-samsung, blackberry, or nexus devices start seeing regular updates. Until that happens, seamless updates are a useless feature Posted via the Android Central App
  • I can understand why an OEM wouldn't want to implement this, since it eats up so much additional space.
  • I agree. The update process now might be an small annoyance but it happens very rarely and doesn't use up several GB of memory. Most manufacturer's versions of Android are much larger than the Nexus devices as well. I'd imagine the ROM on the GS7 is already several GB in size. I wouldn't want the OS taking up 7 GB or whatever just to make updates faster.
  • The ROM in the GS6 is already 7GB so I'd imagine it would be even larger on the GS7. 15GB of OS space is ridiculous!
  • the ROM's on the Nexus 6/6p take up 7 gigs too Posted via the Android Central App
  • Except that memory density is going to go bananas in the next cycle. With Samsung able to pack like 64 levels high, making a 16gb or 32gm from chip will cost the same as a 8gb or 4gb... Posted via the Android Central App
  • Good info, glad to see opt-out options! Hopefully we'll see a built-in recovery partition as well some day (to roll back if issues are encountered). That will take up some more space but all the more reason 64GB should be the minimum storage capacity!
  • I demand htc to release an official update for Android Nougat on the best smartphone I ever had: Htc one m8.
  • HTC 10 have that crown buddy, and I don't even own one Posted via the Android Central App
  • How can the HTC 10 have hte crown of "the best smartphone I ever owned" if I never owned one?
  • Until you own it, it'll have the crown of the best you should own!
  • lol. :)
    Anyone here came from the m8 to the HTC 10? Thoughts? Cheers
  • What makes it good? Speakers? Lack of updates? Poor UI? Weird camera? Posted via the Android Central App
  • Wow cool! Posted via the Android Central App
    for LG G3
  • I've seen nothing yet, other than enhanced Doze, to get me excited about Nougat. I would much rather update manually and save the space. Posted via the Android Central App from my S7 edge
  • My biggest hope is that this will force phone makers to go minimum of 32-64 GB of storage. I'd really wish it was 64, but I'll just be glad if the 16 GB phones disappear.
  • But if the extra space is used for the OS you aren't gaining anything.
  • Well ya it depends on the size of the ROM I believe the bloatest award goes to the GS4 Posted via the Android Central App
  • *Looks sadly at his 16 GB GS4...*
  • Then, add more Ram Posted via the Android Central App
  • Then, add more GB to make up for what they OS uses Posted via the Android Central App
  • But we are already seeing the next gen of memory...4-6gb of RAM, 128GB of storage will be low end in 3 years Posted via the Android Central App
  • Will non-Nexus phones with 7.0 be able to apply Google issued seamless updates without having to wait for manufacturer/provider version?
  • No Posted via the Android Central App
  • Oh well, it was a nice dream, if short. Thanks for the info.
  • I'd assume not. Yet another reason to go with nexus. Posted via the Android Central App
  • I like Nexus phones for the quick updates and pure Android experience, but the biggest draws for me in a phone are big screen in small body, top camera quality, and durability. I'm betting the Note 7 will beat the Nexus (marlin) on at least two, if not all three of those. Will be a tough call.
  • Well I'm sure they'll be neck and neck. What the note 7 won't have however is fast, consistent OS updates or stock Android firmware straight from Google, which are clearly the main reasons I roll with nexus. I like all those things you mentioned too which is why I couldn't be happier with the 6P. A phone as excellent as that makes it an even easier choice to roll with nexus for me atleast Posted via the Android Central App
  • My understanding and what I've read is it'll only work with the next gen of Nexus phones. Past and current, including my 6P, aren't compatible. Posted via the Android Central App
  • Yes, the Moto X4 does this.
  • Why can't it create the new partition only when a new update is available, and ditch the old one once the update is complete?
    This way, it will use the extra image only for the update..
  • No reason, really. Back on the original G1 I used to tinker with live partition editing for apps to SD (which wasn't a feature of Android yet). Shrinking the fat32 storage partition and increasing the ext4 apps partition when my apps partition ran out of space. So I already know it can be done.
  • ok, I made a new post for it here:
  • Sounds like a welcomed process. Nice behind the scenes improvement. One picture at a time--LG V10
  • @Jerry, "And you don't want a future update to try and repartition it — the internal memory was designed to have its record (a map of where each partition lives) written once and never changed" - can you expand on this? I've never heard of a write-once area of memory related to the file system (other than fused memory locations - ex. Samsung Knox flag).
  • After the incident with the original galaxy S with Roger's in Canada no one should try to re partition with an OTA. Posted via the Android Central App
  • Can you give me a link to that or a run down explanation Posted via the beautiful honor 5x with Android m ui theme
  • What thatguy said. When it happened, Samsung was quick to say it was because the storage was designed to only be partitioned once. They make the storage on more than half of the phones out there. The explanation amounted to — Our nand has a 10,000 P/E cycle rating on block zero, but the file record is written to an area with a 2,000 P/E rating and has no wear leveling or bad block management in place. Is that true? I can't say for sure. I go with what they told me because they make the memory and program the controller :P
  • I'm no silicon designer, but it seems odd that the same NAND part would have different P/E ratios for different blocks of memory on the same physical part. And saying that the partition layout should only be written to once, but that it's on a block that supports 2000 cycles also doesn't make sense to me. Thanks for the information though.
  • All I know is that there will be Neko atsume cat Easter eggs and I am excited!!! Posted via the Android Central App
  • Why is it that android rich in software and apps can not seem to implement an update seamless and easy like apple been doing for years? Smh..... Posted via the Android Central App
  • Updating hundreds of different devices is much different than updating one device.
  • Google does just fine with Chromebooks and Microsoft does just fine with Windows, those are on hundreds of different devices.
  • I kinda remember the old xiaomi devices having dual system partitions too. Posted via the Android Central App
  • The phone storage should be completely accessible to the end user(less traditional formatting) but the software, skins, overlays, launchers should NOT be a part of what we have access too - and jeez who would ever buy an iFone with a mere 32gb let alone 16gb, and non expansion.. .. Posted via the Android Central App
  • Since it takes a sizeable amount of space, 64GB of internal storage may be the norm going forward, to allow for the OS seamless updates.
  • So no phone released prior to Nougat launch will ever get this? Good thing it's not a flashy feature. Posted via TCP/IP
  • Yet another reason I want my next phone to be 128gb. On 32gb I've already had to delete a bunch of apps I didn't want to and am running with very little (1-2GB) free. I know that is not recommended. I love apps and plus more retail stores are requiring their apps for discount coupons, etc. And of course apps themselves will only get bigger over time just like PC apps have.
  • So it says that phones will have two partions written into a phone's memory. So even less usable memory for people without SD cards. Great! Posted via the Android Central App
  • This article fails to acknowledge the elephant in the room. Updates in android are completely dysfunctional so long as service providers and retailers with branded android firmware, continue to stand between google and phone owners, blocking updates.
    Given this blocks both firmware and security updates, there is a growing shift in security concerned android users away from android to other more secure OS.
    Ive had 6 successive Sony android phones, purchased a dozen or so samsung phones for kids, and one iphone for my wife. The only phone that gets regular updates is the iphone. Thats going to be the deal breaker when i update my z3 this year.
    So i dont care how easy google makes updates, or how good the very latest android version is. As a loyal and enthusiastic andoid user, I rarely ever get to use the most recent android OS, even when buying my phones outright from Sony or Samsung.
  • The article wasn't meant to address slow/non-existing Android updates. There are countless articles on that already. So, it doesn't fail to acknowledge anything.
  • Who would send all this amazing tech to the devices?
    Personally i don't begrudge my phone the couple of minutes it takes to update, I don't have to have it going every nanosecond of the day....
  • While I know my Nexus 6 will not be able to take advantage of this new feature, I look forward to it on my next Nexus. I, like many others, often put the updates off until an opportune time, since, as mentioned by Jerry, the process can be so lengthy. The "optimizing apps" part of the process kills me.
  • I was hoping it was going to be updates bypassing the manufacturer and network provider
  • Lol. How is that even possible? Manufacturers have to test their own additions on the new OS.
  • That’s how it works with Windows and Chrome OS.