1. August 02, 2004Mallikarjun Chadalapaka, HP1 iSCSI/RDMA: Overview of DA and iSER Mallikarjun Chadalapaka HP

2. August 02, 2004Mallikarjun Chadalapaka, HP2 Agenda Motivation for iSCSI/RDMA iSER and DA? DA: Approach, why, principles iSER: big picture SCSI Read SCSI Write Next steps

3. August 02, 2004Mallikarjun Chadalapaka, HP3 Motivation for iSCSI/RDMA Motivation  Take advantage of the RDMA protocol suite & RNIC hardware.  When RDMA technology advances, so does iSCSI.  Zero-copy, direct data placement can be achieved with generic protocols.  Opportunity for iSCSI protocol to offload some complexity iWARP offers CRC-level reliability on TCP/IP.  iSCSI will be run on RNICs anyway, let’s make it optimal. High-level goal: Run “most efficiently” on generic RNICs.

4. August 02, 2004Mallikarjun Chadalapaka, HP4 So what did we do? 2 discrete steps 1.Distill the data movement needs of iSCSI to propose an architecture for any “Datamover”. DA (Datamover Architecture for iSCSI). 2.Based on the architecture, instantiate a Datamover protocol on RDMAP. iSER (iSCSI Extensions for RDMA).

5. August 02, 2004Mallikarjun Chadalapaka, HP5 Why DA? Principle: iSCSI is “assisted” by a Datamover protocol. But by how much? –Are sessions offloaded? –How about login? –How about discovery? DA draws a line through the iSCSI protocol functionality: –Data movement below, everything else above. –Everything “below the line” is assisted by a Datamover. –The “line” is defined by “Operational Primitives”.

6. August 02, 2004Mallikarjun Chadalapaka, HP6 Datamover Architecture iSCSI layer Datamover layer TCP layer iSCSI layer Datamover layer TCP layer Datamover protocol Datamover Interface (DI) Datamover {Layer, Protocol, Interface} Datamover- dependent

7. August 02, 2004Mallikarjun Chadalapaka, HP7 DA Design principles Not a wire protocol spec. A functional model of interactions within an iSCSI node. Agnostic about hardware or software implementations. Independent of iSCSI revision specifics, or of any Datamover protocol. Motivated by RDMA but designed not just for iWARP.

8. August 02, 2004Mallikarjun Chadalapaka, HP8 iSER Big picture Layered on RDMAP protocol. iSCSI still requires direct TCP access for bootstrapping (login). –Transition to RDMA mode along with FFP. Same iSCSI well- known port –Same discovery. SCSI iSCSI TCP Datamover Interface iWARP protocol suite RNIC iWARP Verbs Generic RDMA over TCP/IP 1 RDMAP DDP MPA iSER 2 A TCP-based implementation is shown as an example.

9. August 02, 2004Mallikarjun Chadalapaka, HP9 iSCSI/iSER: Port to Port (FFP) Initiator SCSI iSER RDMAP DDP + MPA TCP connection Target I_T Nexus iSCSI Session SCSI target port RDMAP Stream RDMAP Stream DDP Stream DDP Stream iSCSI/iSER connection iSCSI/iSER connection iSCSI Connection iSCSI Connection iSCSI I_T Nexus iSCSI Session SCSI initiator port RDMAP Stream RDMAP Stream DDP Stream DDP Stream iSCSI/iSER connection iSCSI/iSER connection iSCSI Connection iSCSI Connection Verbs DI Initiator SCSI TCP connection Target I_T Nexus SCSI target port iSCSI Connection iSCSI Connection iSCSI I_T Nexus SCSI initiator port iSCSI Connection iSCSI Connection iSCSI Session

10. August 02, 2004Mallikarjun Chadalapaka, HP10 SCSI Read Initiator Command Request Command Complete Target Command encapsulated in a Send Type Message (Advertises initiator’s STag for the SCSI buffer) RDMA Write Message Read data back to the host SCSI Response PDU Encapsulated in a Send Type Message Data transfer (all associated RDMA Writes complete) SCSI Data-in PDU SCSI Command PDU SCSI Response PDU

11. August 02, 2004Mallikarjun Chadalapaka, HP11 SCSI Write Initiator Command Request Command Complete Target Command encapsulated in a Send Type Message (Advertises initiator’s STag for the SCSI buffer) Response encapsulated in a Send Type Message Data transfer (all associated RDMA Reads complete) R2T PDU SCSI Command PDU SCSI Response PDU Write data from the host RDMA Read Request Message

12. August 02, 2004Mallikarjun Chadalapaka, HP12 Dependencies & Non-dependencies DA is dependent only on iSCSI. iSER is dependent on DA & iSCSI. iSER is dependent only on the RDMAP protocol among the iWARP suite. iSER & DA are not dependent on the RDMA Verbs.

13. August 02, 2004Mallikarjun Chadalapaka, HP13 Now & Next steps I-Ds submitted in July 2003. Now in their -02 revisions. http://www.ietf.org/internet-drafts/draft-chadalapaka-iwarp-da-02.txt http://www.ietf.org/internet-drafts/draft-ko-iwarp-iser-02.txt Discussion on the IPS (and some on RDDP) reflector. Proposal is to make DA and iSER drafts as the official IPS WG drafts, to eventually become standards-track RFCs.