Can we apply immutabilty in Azure blob storage on already existing data in blob

@Az Techie :

Since the immutabilty is at a container level/scope therefore you can write access policies to protect your data from overwrites and deletes for existing blobs as well as a member of a particular container. However, you need to make sure you have enabled the immutable Blob in Data Protection section while creating the Storage account.

Immutable storage for Azure Blob Storage enables users to store business-critical data in a WORM (Write Once, Read Many) state. While in a WORM state, data cannot be modified or deleted for a user-specified interval. By configuring immutability policies for blob data, you can protect your data from overwrites and deletes.

Immutable storage for Azure Blob Storage supports two types of immutability policies:

Time-based retention policies: With a time-based retention policy, users can set policies to store data for a specified interval. When a time-based retention policy is set, objects can be created and read, but not modified or deleted. After the retention period has expired, objects can be deleted but not overwritten. To learn more about time-based retention policies, see Time-based retention policies for immutable blob data.

Legal hold policies: A legal hold stores immutable data until the legal hold is explicitly cleared. When a legal hold is set, objects can be created and read, but not modified or deleted. To learn more about legal hold policies, see Legal holds for immutable blob data.

References :
https://learn.microsoft.com/en-us/azure/storage/blobs/immutable-policy-configure-container-scope?tabs=azure-portal