ISCSI Conformance Testing and Testing Tool Requirement-Cedar Herald Index

iSCSI conformance testing is testing to determine whether an iSCSI Initiator/Target meets the iSCSI standard.

SCSI and iSCSI Protocol

The Small Computer System Interface (SCSI) is a family of protocols for communicating with I/O devices, especially storage devices. SCSI is based on client-server model. SCSI clients, called "initiators", issue SCSI commands to request services from components, logical units of a server known as a "target". A "SCSI transport" maps the client-server SCSI protocol to a specific interconnect. An Initiator is one endpoint of a SCSI transport and a target is the other endpoint.

ISCSI Conformance Testing and Testing Tool Requirement

Internet Small Computer System Interface (iSCSI) protocol uses TCP/IP as SCSI transport. By transporting SCSI packets over TCP/IP, iSCSI provides an interoperable solution which can take advantage of existing Internet infrastructure, Internet management facilities, and address distance limitations. Unlike traditional Fibre Channel, which requires special-purpose cabling, iSCSI can run on the existing network infrastructure. It has become a popular storage area network (SAN) protocol because of its scalability and economic benefits. The protocol is defined in RFC 3720 and updated in RFC 5048.

ISCSI Conformance Testing and Testing Tool Requirement

iSCSI Conformance Testing

With the moving of SCSI transport layer from the traditional reliable bus structure to the far more unreliable TCP/IP network, a fairly reasonable amount of complexity has been introduced into iSCSI:

ISCSI Conformance Testing and Testing Tool Requirement

Login/Logout processes are needed. Security/Operational parameters need to be negotiated during login. CHAP or other authentication method may be used during login. Multiple sessions/connections may be required. Multiple error recovery level may be implemented. ...

In one word, although the economic cost of iSCSI may be lower than others, the protocol itself is not that simple.

Since the approval of the protocol, iSCSI has been steadily gaining acceptance among end users and storage vendors. Nowadays, there exist a large number of iSCSI initiator/target implementations on the market, either commercial or free/open source. These implementations vary in functionalities and protocol conformance.

Conformance testing is testing to determine whether a system meets some specified standard. It is often performed by external organizations, sometimes the standards body itself, to give greater guarantees of compliance. Products tested in such a manner are then advertised as being certified by that external organization as complying with the standard. For iSCSI protocol (or other data networking and storage protocols), The University of New Hampshire InterOperability Laboratory (UNH-IOL) is one of the premier neutral, third-party laboratory who offers test suites for iSCSI conformance testing.

As the introduction part in these test suites says: These tests are designed to determine if an iSCSI product conforms to specifications defined in both IETF RFC 3720 iSCSI (hereafter referred to as the “iSCSI Standard”) as well as updates as contained in IETF RFC 5048 iSCSI Corrections and Clarifications RFC (hereafter referred to as “iSCSI Corrections and Clarifications”). Successful completion of all tests contained in this suite does not guarantee that the tested device will successfully operate with other iSCSI products. However, when combined with satisfactory operation in the IOL’s interoperability test bed, these tests provide a reasonable level of confidence that the Device Under Test (DUT) will function properly in many iSCSI environments.

iSCSI conformance testing mainly contains the following aspects:

Login Phase Conformance

Test negotiation key-value pairs; test various flags: CSG, NSG, C bit, T bit...

Full Feature Phase Conformance

Test sequence numbers (CmdSN, DataSN, R2TSN); test SCSI Command/Response, Task Management Function Request/Response, Text Request/Response, NOP-In/NOP-Out, SNACK Request...