Method and system for supporting read operations with CRC for iSCSI and iSCSI chimney

Abstract

Certain embodiments of the invention may be found in a method and system for performing SCSI read operations with a CRC via a TCP offload engine. Aspects of the method may comprise receiving an iSCSI read command from an initiator. Data may be fetched from a buffer based on the received iSCSI read command. The fetched data may be zero copied from the buffer to the initiator and a TCP sequence may be retransmitted to the initiator. A digest value may be calculated, which may be communicated to the initiator. An accumulated digest value stored in a temporary buffer may be utilized to calculate a final digest value, if the buffer is posted. The retransmitted TCP sequence may be processed and the fetched data may be zero copied into an iSCSI buffer, if the buffer is posted. The calculated final digest value may be communicated to the initiator.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS / INCORPORATION BY REFERENCE[0001]The present application is a continuation-in-part of application No. 10 / 652,267 filed on Aug. 29, 2003 now U.S. Pat. No. 7,346,701, which makes reference to, claims priority to and claims benefit from U.S. Provisional Patent Application Ser. No. 60 / 408,617 filed on Sep. 6, 2002, U.S. Provisional Patent Application Ser. No. 60 / 407,165 filed on Aug. 30, 2002, U.S. Provisional Patent Application Ser. No. 60 / 456,260 filed on Mar. 20, 2003 and U.S. Provisional Patent Application Ser. No. 60 / 456,265 filed on Mar. 20, 2003.[0002]This application also makes reference to, claims priority to, and claims the benefit of:[0003]U.S. Provisional Patent Application Ser. No. 60 / 580,977 filed Jun. 17, 2004; and[0004]U.S. Provisional Patent Application Ser. No. 60 / 660,750 filed Mar. 11, 2005.[0005]The following application makes reference to:[0006]U.S. patent application Ser. No. 11 / 156,289 filed Jun. 17, 2005;[0007]U.S. patent ap...

AI Technical Summary

Problems solved by technology

TCP / IP chimney offload redirects most of the TCP / IP related tasks to a network controller for processing, which frees up networking-related CPU resources overhead.

Although TCP / IP offload is not a new technology, conventional TCP / IP offload applications have been platform specific and were not seamlessly integrated with the operating system's networking stack.

As a result, these conventional offload applications were standalone applications, which were platform dependent and this severely affected deployment.

Furthermore, the lack of integration within an operating system's stack resulted in two or more independent and different TCP / IP implementations running on a single server, which made such systems more complex to manage.