Azure offers various storage tiers for storing data. The available tiers are:
Premium: The premium tier provides the fastest access to stored data and is optimized for low latency use cases. The data is stored in high performance solid-state drives. Premium storage tier is only available for Azure Blob storage, while the other tiers are available for both Azure Blob as well as the General Purpose v2 (GPv2) storage.
Hot: For storing frequently accessed data. It offers the lowest access cost but has a higher storage cost than Cool and Archive tiers.
Cool: Optimized for data that is not accessed frequently i.e. data that can be stored with no access for 30 days. It has lower storage cost than Hot tier but access costs are higher.
Archive: For storing rarely accessed data that can be stored for at least 180 days. Data stored in the archive tier is offline i.e. users do not have read or write access. To access data from the archive tier, the data needs to be “rehydrated” by converting the blob tier from Archive to hot or cool. It may take up to 15 hours to complete the rehydration process.
There are multiple ways to change the storage tiers, it can be done at the individual blob level on Azure portal or through PowerShell at the container level. An enterprise customer may want to automate the storage tier conversion based on certain factors such as freshness of data, data access frequency, size of the container etc. This can be achieved by using lifecycle management which is available as a feature for Azure storage accounts.