【正文】 etadata xNo contention detection or resolution xNo allocation or management of blocks C OMMUNICAITON UNIVERSITY of CHINA STORAGY LABORATORY iSCSI: Past, Present, Future Objectbased Storage System ?Idea: push more intelligence onto disk unit – Target manages block allocation – Target defines objects and maps their blocks – Target manages object metadata ?Enhancements to SCSI mand set ?Must rewrite file systems to use objects C OMMUNICAITON UNIVERSITY of CHINA STORAGY LABORATORY iSCSI: Past, Present, Future ANSI Project T10/1355D ?SCSI ObjectBased Storage Device Commands ?Final Revision 10, 30 July 2023 ―To provide efficient operation of I/O logical units that manage the allocation, placement and accessing of variablesize datastorage containers called objects.‖ C OMMUNICAITON UNIVERSITY of CHINA STORAGY LABORATORY iSCSI: Past, Present, Future iSCSI: Objectstore ?All OSD mands are bidirectional ?200byte CDB requires use of iSCSI AHS – Reading a PDU header requires 2 steps: ?Read 48byte Basic header, extract AHSLength ?Read following AHSLength bytes – Header digest (CRC) is problematic ?Use AHSLength value to read AHS headers and CRC ?Use CRC to check plete header after read done ?If AHSLength has error – input may block! C OMMUNICAITON UNIVERSITY of CHINA STORAGY LABORATORY iSCSI: Past, Present, Future Tracking SCSI Standards ?iSCSI version 0 (RFC 3720) based on: – SAM2 Final revision 24, 11September2023 – SBC Final revision 8, 13November1997 ?Upgrade to SAM3 project T10/1561D? – Final revision 14, 21September2023 ?SAM4 project T10/1683D – Final revision 14, 8May2023 ?SAM5 project T10/2104D – Revision 05, 11May2023 C OMMUNICAITON UNIVERSITY of CHINA STORAGY LABORATORY iSCSI: Past, Present, Future iSCSI: Research Areas ?Dynamic parameter adjustment – Respond to changes in application load – Respond to changes in work conditions ?Using parameters between levels –., let iSCSI use TCP’s RTT to keep pipe full ?Negotiate limits but operate at other values – Target controls burst sizes, outstanding R2Ts – Initiator controls connections, unsolicited data C OMMUNICAITON UNIVERSITY of CHINA STORAGY LABORATORY iSCSI: Past, Present, Future iSCSI: Research Areas ?Scheduling multiple connections in session – What criteria to use? – Let different connections carry different info? ?Reinstating sessions in order to renegotiate – Only limited differences between connections ?New file systems ?New caching schemes C OMMUNICAITON UNIVERSITY of CHINA STORAGY LABORATORY iSCSI: Past, Present, Future ANY QUESTIONS? THANK YOU! C OMMUNICAITON UNIVERSITY of CHINA STORAGY LABORATORY iSCSI: Past, Present, Future ? 靜夜四無鄰，荒居舊業(yè)貧。 。 :15:4018:15:40March 27, 2023 ? 1意志堅強的人能把世界放在手中像泥塊一樣任意揉捏。 :15:4018:15Mar2327Mar23 ? 1越是無能的人，越喜歡挑剔別