All update activity takes place on partitions in the unused slot.
So, how does it work?
The goal of this feature is to make updates fault resistant by keeping the unused slot as a fallback.
Seamless system update feature is already available on the Googles Pixel and Pixel XL smartphones.
Therefore, streaming A/B updates need almost no temporary storage and need just enough for roughly 100kB of metadata.
source: www.techworm.net
