Demystifying A/B Partitions: A Look at Android’s Seamless Updates
Apr. 2, 2024Over the past decade, Android has improved both visually and internally, making it an efficient operating system. One feature that quietly enhances your experience is Seamless Updates. You may have seen Android experts throw this term around from time to time. So let’s break down what Seamless Updates mean on Android.
Seamless Updates on Android
However, with seamless updates and what Google callsA/B partitioning, Android installs an update parallelly without interruptions. This way, a devicewould only need a usual restartonce installed. Also, the updates in the A/B scheme can be streamed rather than downloading and unzipping the update package.
This is achieved by havingtwo separate boot, system, and vendor partitions. If the technical jargon is too much for you, leave the explaining to us.
The internal structure of an Android device without seamless updates looks like this. The device can only start applying the update when it restarts, which is inconvenient.
And here’s the architecture of a device with A/B partitions and seamless updates. Notice how the Boot, System, and Vendor partitions are divided into two?
Your current active slot could be either A or B. Regardless, say you’re on Slot_A with Android 14 and receive an update to Android 15, as soon as you hitDownload and install, Android will start unpacking and installing the necessary Boot, System, and Vendor components to the opposite slot, i.e., Slot_B which consists of Boot_B, System_B, and Vendor_B. At this point, Slot_A is still your active slot.
However, as soon as you hit restart, Android verifies the update and checks for the current active slot. If everything goes right, it sets the opposite slot as active and boots into the same. Here’s how to visualize it.
You may ask,“All of this just for convenience sake?” No, Seamless Updates have many other advantages besides convenience:
What are your thoughts on seamless updates? What other similar changes to the Android architecture should Google bring? Pitch your ideas in the comments below.
