What is iSCSI Task and PDU

Here is a listing of technical definitions for iSCSI Task and PDU.

Originator: In a negotiation or exchange, the party that initiates the negotiation or exchange.

Responder: In a negotiation or exchange, the party that responds to the originator of the negotiation or exchange.


iSCSI Transfer Direction: The iSCSI transfer direction is defined with regard to the initiator. Outbound or outgoing transfers are transfers from the initiator to the target, while inbound or incoming transfers are from the target to the initiator.

iSCSI Task: An iSCSI task is an iSCSI request for which a response is expected.

PDU (Protocol Data Unit): The initiator and target divide their communications into messages. The term “iSCSI protocol data unit” (iSCSI PDU) is used for these messages.


Recovery R2T: An R2T generated by a target upon detecting the loss of one or more Data-Out PDUs through one of the following means: a digest error, a sequence error, or a sequence reception timeout. A recovery R2T carries the next unused R2TSN, but requests all or part of the data burst that an earlier R2T (with a lower R2TSN) had already requested.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter