fs.azure.account.expect.header.enabled: This configuration parameter is used to specify whether you wish to send a expect 100 continue header with each append request or not. It is configured to true by default. This flag configures the client to check with the Azure store before uploading a block of data from an output stream. This allows the client to throttle back gracefully -before actually attempting to upload the block. In experiments this provides significant throughput improvements under heavy load. For more information : - -US/docs/Web/HTTP/Headers/Expect