Tiers that balance storage and access cost: Hot (frequent access), Cool (30-day minimum), Cold (90-day minimum, immediate reads), and Archive (180-day minimum, offline). Deleting or moving a blob before the minimum incurs an early deletion fee.
In DP-900: legal copies that are almost never read → Archive, which requires rehydrating the blob to an online tier before reading it (it can take hours). Lifecycle management policies move blobs between tiers automatically.
Blob Storage access tiers is a concept that can show up on the exam. Check the full guide to see it in context.