Ten years of photos
The shop's website shows today's menu photos thousands of times a day. It also keeps every receipt for seven years for the tax office — files nobody reads unless there's an audit. Paying the same price for both would be silly, and losing either would be worse.
Azure Storage lets you choose two things separately: how many copies, where (redundancy) and how often you'll read (the access tier). Today you'll learn both and write the calculator that picks the cheapest tier.
Storage accounts and blobs
A storage account (general-purpose v2 for nearly everything) has a globally unique name of 3–24 lowercase letters and digits, and gives you four services: Blob storage for unstructured files in containers, Files for SMB/NFS file shares, Queues for simple messages and Tables for key-value data. VM disks are managed disks, a separate resource.
- Hot: frequently read. Highest storage price, cheapest reads.
- Cool: infrequent reads, kept at least 30 days.
- Cold: rarely read, kept at least 90 days.
- Archive: offline, kept at least 180 days. Cheapest to store, but you must rehydrate a blob to hot or cool (taking hours) before reading it.
- Delete or move a blob before its minimum and you pay an early-deletion charge for the remaining days.
- Lifecycle management rules can move blobs down the tiers automatically as they age.
Older books list three tiers. The cold tier arrived in 2023, between cool and archive.