Google is placing new guidelines in place for Android 11: it’ll make assist for Android’s “seamless update” characteristic obligatory for units launching with the brand new OS. The information involves us through an Android supply code commit first noticed by XDA Developers, which reads, “Require Virtual A/B on R launches.” In English, this implies the seamless replace system, which requires two partitions (labeled “A” and “B”), might be required on Android R, aka Android 11.
Android’s seamless replace system was introduced in Android 7.0 Nougat (it was truly borrowed from Chrome OS) as a method to scale back the downtime attributable to OS updates and to supply a restoration mechanism in case an replace applies incorrectly. Applying an replace to an working system normally means taking the OS offline for an prolonged interval of downtime. On Android, earlier than seamless updates, the cellphone would boot into restoration and could possibly be caught on the “Installing System Update” display for as much as 25 minutes. That’s lots of downtime, and through this time you may’t run any apps, see any textual content messages, or get any cellphone calls. The downtime occurs as a result of updating the system recordsdata requires taking the system partition offline, however the seamless replace system fixes this by simply having a second copy of the system partition.
As referenced within the commit, the 2 system partitions are known as “A” and “B.” Normally they’re actual copies of one another. One of the system partitions is on-line and getting used for the cellphone working system, and the opposite one is offline, simply sitting there. When it comes time to use an replace, the replace is utilized to the offline partition first. So for those who’re working on system partition A, then it is system partition B that will get up to date. This occurs, properly, seamlessly, within the background, and whereas system partition B is having recordsdata up to date, you may nonetheless do all the traditional cellphone stuff on system partition A. Instead of getting to stare at a cellphone locked to an “Installing System Update” display for 25 minutes, the cellphone solely has an “installing system update” notification that you may ignore.
Because you’ve got two system partitions, the cellphone by no means has an prolonged interval of downtime. Once the replace on the offline partition is accomplished, the cellphone asks for a reboot, and at the moment it is going to swap energetic partitions. So for those who have been working on partition A and partition B bought up to date, the cellphone will swap to working on the freshly up to date B partition, and A might be up to date at a later time, normally when the cellphone is idle and on a charger.
The different profit to seamless updates is that if one thing goes incorrect throughout an replace and a partition turns into unbootable, it nonetheless has the opposite partition as a backup. Android is wise sufficient to set a flag when it swaps to a brand new partition for the primary boot, and if that boot would not full, it will probably swap again and boot into the older model of the OS. From there it will probably contact replace servers once more, obtain the OS recordsdata once more, and attempt to re-apply the replace. Without seamless updates, a failed OS replace would flip your cellphone right into a brick, and recovering it could require a PC and particular software program, however the seamless replace system can seamlessly get better, too.
Many OEMs have already adopted seamless updates voluntarily, like Google, OnePlus, Nokia, LG, Motorola, HTC, Sony, and Asus. The greatest holdout is Samsung—why is it at all times Samsung?—which nonetheless requires its telephones to go offline for an prolonged interval. It’s straightforward to make the “Well, Samsung phones never get updates anyway” joke, however they do nonetheless get month-to-month safety updates, so this required downtime remains to be occurring each month. Making this characteristic obligatory for Android 11 will imply Samsung will lastly be compelled to undertake it, together with every other stragglers, normally OEMs in China.
Seamless updates do have some downsides, specifically that two system partitions use extra space for storing than one system partition. As a part of the A/B partition push, Google did lots of work to slim down what a system partition seems like and really reduce the scale in half earlier than it wanted to be doubled, so the year-over-year change was not that top. Google has a big FAQ on the A/B partition system and has detailed storage numbers for the 2016 Pixel 1, which is when this primary shipped, saying, “For the Pixel A/B and non-A/B variants tested internally (only A/B shipped), the space used differed by only 320MiB. On a 32GiB device, this is just under 1%. For a 16GiB device this would be less than 2%, and for an 8GiB device almost 4% (assuming all three devices had the same system image).”
In the FAQ, Google recommends utilizing the A/B partitions on each storage configuration all the way down to 8GB, which covers even the lowest-end smartphones. Some of Google’s necessities, like obligatory encryption assist, have shipped with exceptions for low-end devices up to now, so it is attainable this would possibly not apply to cheaper telephones. To know for positive, we would have to see the Android Compatibility Definition Document for Android 11, which is not revealed but.