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https://issues.apache.org/jira/browse/HADOOP-19178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17848360#comment-17848360
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Steve Loughran edited comment on HADOOP-19178 at 5/22/24 2:17 PM:
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makes sense, I've been undertesting it anyway.

It'd be good for any form of graceful degradation of wasb driver

* immediate PR to warn its deprecated for trunk, 3.4 and 3.3.9 branches, docs 
updated
* after the cut, have some stub fs to fail on instantiate() with meaningful 
error message. We did this with s3n, way back. No attempt at migration, just a 
"gone, go look at at the docs"


was (Author: ste...@apache.org):
makes sense, I've been undertesting it anyway.

It'd be good for any form of graceful degradation of wasb driver

* immediate PR to warn its deprecated for trunk, 3.4 and 3.3.9 branches, docs 
updated
* after the cut, have some stub fs to fail on instantiate() with meaningful 
error message. We did this with s3n, way back. No attempt at migration, just a 
"done, go look at at the docs"

> WASB Driver Deprecation and eventual removal
> --------------------------------------------
>
>                 Key: HADOOP-19178
>                 URL: https://issues.apache.org/jira/browse/HADOOP-19178
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/azure
>    Affects Versions: 3.4.0
>            Reporter: Sneha Vijayarajan
>            Assignee: Sneha Vijayarajan
>            Priority: Major
>             Fix For: 3.4.1
>
>
> *WASB Driver*
> WASB driver was developed to support FNS (FlatNameSpace) Azure Storage 
> accounts. FNS accounts do not honor File-Folder syntax. HDFS Folder 
> operations hence are mimicked at client side by WASB driver and certain 
> folder operations like Rename and Delete can lead to lot of IOPs with 
> client-side enumeration and orchestration of rename/delete operation blob by 
> blob. It was not ideal for other APIs too as initial checks for path is a 
> file or folder needs to be done over multiple metadata calls. These led to a 
> degraded performance.
> To provide better service to Analytics customers, Microsoft released ADLS 
> Gen2 which are HNS (Hierarchical Namespace) , i.e File-Folder aware store. 
> ABFS driver was designed to overcome the inherent deficiencies of WASB and 
> customers were informed to migrate to ABFS driver.
> *Customers who still use the legacy WASB driver and the challenges they face* 
> Some of our customers have not migrated to the ABFS driver yet and continue 
> to use the legacy WASB driver with FNS accounts.  
> These customers face the following challenges: 
>  * They cannot leverage the optimizations and benefits of the ABFS driver.
>  * They need to deal with the compatibility issues should the files and 
> folders were modified with the legacy WASB driver and the ABFS driver 
> concurrently in a phased transition situation.
>  * There are differences for supported features for FNS and HNS over ABFS 
> Driver
>  * In certain cases, they must perform a significant amount of re-work on 
> their workloads to migrate to the ABFS driver, which is available only on HNS 
> enabled accounts in a fully tested and supported scenario.
> *Deprecation plans for WASB*
> We are introducing a new feature that will enable the ABFS driver to support 
> FNS accounts (over BlobEndpoint) using the ABFS scheme. This feature will 
> enable customers to use the ABFS driver to interact with data stored in GPv2 
> (General Purpose v2) storage accounts. 
> With this feature, the customers who still use the legacy WASB driver will be 
> able to migrate to the ABFS driver without much re-work on their workloads. 
> They will however need to change the URIs from the WASB scheme to the ABFS 
> scheme. 
> Once ABFS driver has built FNS support capability to migrate WASB customers, 
> WASB driver will be declared deprecated in OSS documentation and marked for 
> removal in next major release. This will remove any ambiguity for new 
> customer onboards as there will be only one Microsoft driver for Azure 
> Storage and migrating customers will get SLA bound support for driver and 
> service, which was not guaranteed over WASB.
>  We anticipate that this feature will serve as a stepping stone for customers 
> to move to HNS enabled accounts with the ABFS driver, which is our 
> recommended stack for big data analytics on ADLS Gen2. 
> *Any Impact for* *existing customers who are using ADLS Gen2 (HNS enabled 
> account) with ABFS driver* *?*
> This feature does not impact the existing customers who are using ADLS Gen2 
> (HNS enabled account) with ABFS driver.
> They do not need to make any changes to their workloads or configurations. 
> They will still enjoy the benefits of HNS, such as atomic operations, 
> fine-grained access control, scalability, and performance. 
> *Official recommendation*
> Microsoft continues to recommend all Big Data and Analytics customers to use 
> Azure Data Lake Gen2 (ADLS Gen2) using the ABFS driver and will continue to 
> optimize this scenario in future, we believe that this new option will help 
> all those customers to transition to a supported scenario immediately, while 
> they plan to ultimately move to ADLS Gen2 (HNS enabled account).
>  *New Authentication options that a WASB to ABFS Driver migrating customer 
> will get*
> Below auth types that WASB provides will continue to work on the new FNS over 
> ABFS Driver over configuration that accepts these SAS types (similar to WASB)
>  * SharedKey
>  * Account SAS
>  * Service/Container SAS
> Below authentication types that were not supported by WASB driver but 
> supported by ABFS driver will continue to be available for new FNS over ABFS 
> Driver
>  * OAuth 2.0 Client Credentials
>  * OAuth 2.0: Refresh Token
>  * Azure Managed Identity
>  * Custom OAuth 2.0 Token Provider
> ABFS Driver SAS Token Provider plugin present today for UserDelegation SAS 
> and Directly SAS will continue to work only for HNS accounts.



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