This is ignored if is set, because this feature is incompatible with raw write SMB requests If enabled, raw writes allow writes of 65535 bytes in one packet. This typically provides a major performance benefit for some very, very old clients. However, some clients either negotiate the allowable block size incorrectly or are incapable of supporting larger block sizes, and for these clients you may need to disable raw writes. In general this parameter should be viewed as a system tuning tool and left severely alone. yes read raw async smb echo handler