Impact of Soft Delete Restoration on Blob Timestamps in Azure Blob Storage

Question

Given that Lifecycle Managment Policy and soft deletes are both enabled and configured in an Azure Blob Storage account, I want to restore a soft-deleted blob that was deleted by Lifecycle Management Policy.

When the blob is restored, will its last modified date be set to the restoration date? Or will it retain its original last modified date? Will it retain its original created at date?

In the case that the blob retains its original last modified date and created at date, the Lifecycle Management Policy would delete the blob upon restoration because the blob would be past its retention period.

Is there any way to retain a restored blob after getting soft deleted by the Lifecycle Management Policy without it getting deleted automatically?

Answer 1

Hi Khushaal Kurswani,
You're correct that the LastModified date of a blob in Azure Blob Storage is system-managed and cannot be directly modified. The BlobProperties.LastModified property is indeed a read-only property, and there is no setter for it.

I suggest few steps you can take to troubleshoot the issue. There are a few indirect ways to influence the LastModified date:

Copying the Blob: You can create a copy of the blob. When you copy a blob, the new blob will have a new LastModified date corresponding to the time of the copy operation. This effectively gives you a new blob with a current LastModified date.

Updating Metadata or Properties: Any operation that modifies the blob, including updating its metadata or properties, will change the LastModified date. For example, you can add or update a metadata key-value pair to trigger an update to the LastModified date

Re-uploading the Blob: If you re-upload the blob, it will have a new LastModified date corresponding to the time of the upload. This is similar to copying the blob but involves uploading the data again.

Unfortunately, for a soft-deleted blob, these operations would need to be performed after restoring the blob, as the LastModified date cannot be directly modified during the soft-deleted state.
For more information:
https://learn.microsoft.com/en-us/dotnet/api/azure.storage.blobs.models.blobproperties.lastmodified?view=azure-dotnet

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