Why You Require Persistent Data Across Flashing

Flashing the rootfs partition to update the filesystem must not change or erase the system identity, user account information, or user data. The persistent partitions store user data, metadata, and SSH-host keys (the system's identity for SSH connections). Because the persistent partitions (as the name suggests) are not changed by bootburn flashing or drive update, persistent partitions are required to store such data across flashing.