In April 2014 the IETF Storage Maintenance (STORM) working group published RFC 7143, a consolidated standards track document for all things iSCSI. We’re happy to report that the iSCSI Consortium has completed its efforts to revise our Login Phase, Full Feature Phase, and Multi-connection test suites in order to provide you with the most accurate and up-to-date results.
There were some minor changes to the standard that should not dramatically affect existing implementations. Section 2.3 provides a summary and the most significant changes are discussed below. The good news is that existing compliant implementations will still find themselves mostly compliant.
In RFC 5048 (iSCSI Corrections and Clarifications), the TaskReporting key was introduced for the negotiation of the new task completion reporting semantics. Our past test suites did not require Devices Under Test (DUTs) to understand this TaskReporting key. With the release of the updated standard, this key MUST be implemented by all iSCSI Initiators and Targets (i.e., they MUST NOT respond to the key with TaskReporting=NotUnderstood). Implementations that do not support ResponseFence or FastAbort behavior must simply negotiate a value of “RFC3720” in order to use the original task completion reporting semantics.
Another major change is the deprecation of four keys: IFMarker, OFMarker, IFMarkInt, and OFMarkInt, as these keys have been long unused. The updated standard officially forbids their use. An implementation receiving these keys should respond with a value of “Reject”. Further details can be found in RFC 7143 section 13.25.
The original iSCSI specification, RFC 3720, allowed for IANA-registered public extension keys, which began with the “X#”, “Y#”, and “Z#” prefixes. These have been deemed unnecessary, and RFC 7143 section 14 removes them: “These public extension formats (X#, Y#, Z#) MUST NOT be used, with the exception of the existing X#NodeArchitecture key.”
If you are an iSCSI Consortium Member and have questions regarding the updated standard please Contact Us. Members can request access to our Remote Test Server which allows companies to remotely perform our Target Login and Target Full Feature Phase test suites without the constraints of requesting a full round of testing. Many members find this useful during debugging.
What else can iSCSI implementers look forward to? Along with the Consolidated iSCSI Standard, the STORM Working Group released RFC 7144, iSCSI Features Update. This document was necessitated by the fact that the iSCSI Protocol is based on the version 2 of the SCSI Architectural Model (SAM-2). New SCSI features introduced in subsequent versions (SAM-3, SAM-4, and SAM-5) are not usable under RFC 7143 alone. RFC 7144 introduces the iSCSIProtocolLevel operational parameter to allow the enabling of the new features defined in RFC 7144. Keep your eye out for a new iSCSI Consortium test suite for RFC 7144-compliant implementations in the coming year!
If you are looking for attentional information on the iSCSI standard we now offer entry-level training sessions for current and non-members. The 2-day course is geared for beginner-level developers, but can be tailored to fit the needs of your engineers. See our website or Contact Us for more information.