HADOOP-11693 mitigated the problem of HMaster aborting regionserver due to Azure Storage Throttling event during HBase WAL archival. The way this was achieved was by applying an intensive exponential retry when throttling occurred.
As a second level of mitigation we will change the mode of copy operation if the operation fails even after all retries -i.e. we will do a client side copy of the blob and then copy it back to destination. This operation will not be subject to throttling and hence should provide a stronger mitigation. However it is more expensive, hence we do it only in the case we fail after all retries