All Android operating systems before Android 7.0 Nougat has the same update method. First the file will be downloaded, phone reboots and the update will be applied. It will take few minutes to get the update completed, at least until the update is completely installed. With Nougat’s new “Seamless Updates,” this method is ending. Nougat’s new update feature will utilize a Dual partitions setup.
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Nougat update will use Dual partitions
Google’s Chrome OS had this feature already. It will update the OS in the background and a quick reboot fill finish the process. This feature will not be available on device which were not launched with Android Nougat. Updated device can’t support this feature, only devices that ship with the new Android Nougat can utilize this new method. The reason is, this method need two system partitions to work, most of the existing Android smartphones only has one partition.
There will be two portions with the same file, one active and one dormant, both will mirror each other. When an update is available, the active partition will download it, the dormant partition will install it. A later reboot will activate the dormant partition and formerly active partition will become dormant. This makes the entire update process faster and it also works as a backup system.
Google has moved to a new highly compressed file system called the SquashFS, this will help the space issues due to the Dual partitions. We will also start to see device ship with Android Nougat will have a minimum 32GB of internal storage.