What is hierarchical namespace in Microsoft Azure Data Lake storage (Gen2)?

4
votes

I read Microsoft's document regarding it. link -> https://docs.microsoft.com/en-us/azure/storage/blobs/data-lake-storage-namespace. But unable to understand it clearly.

Can anyone please help me to understand it in layman term / simple language?

How this feature separates ADLS from Azure Blob storage?

1
azureazure-data-lake
Kindly go through youtube.com/watch?v=McJj_N-pjgI and blue-granite.com/blog/… – CHEEKATLAPRADEEP-MSFT

1 Answers

6
votes

The summary, for now, is that Hierarchical Namespace changes Azure Storage to a more ADLS Gen1 style store in practice, but with a compromise of losing some Azure Blob Storage based functionality.

Hierarchical Namespace gains you:

  • A folder structure that behaves more like a traditional OS File system in terms of moves and renames
  • Fine-grain AAD based Access Control at the directory/sub-directory level

At the same time, you lose Blob Storage features including:

  • Blob Soft Delete (delete/recover blobs)
  • Custom Domain, Azure CDN, Azure Search integration in Azure Portal UI
  • Blob Lifecycle Management in UI (Archiving/Deleting/Warming up blobs by the filter on schedule)
  • Limited support of Blob Storage API

In practice, you can expect to experience some inconsistent incompatibilities with anything that tries to interact with Azure Storage. It might work 100%, it might refuse to work at all (or not list the Storage Account as an option, if using Azure Portal UI wizards), or it might work partially. Without knowing the underlying implementation, it's difficult to predict testing.

But, things are still fluid. There are definitely signs that these compromises are due to be addressed in the road-map, especially based from the list of known issues https://docs.microsoft.com/en-us/azure/storage/blobs/data-lake-storage-known-issues.