Internet Small Computer Systems Interface (iSCSI)
RFC 3720
| Document | Type |
RFC
- Proposed Standard
(April 2004)
Errata
IPR
Obsoleted by RFC 7143
Was
draft-ietf-ips-iscsi
(ips WG)
|
|
|---|---|---|---|
| Authors | Efri Zeidner , Constantine Sapuntzakis , Mallikarjun Chadalapaka , Julian Satran , Kalman Meth | ||
| Last updated | 2020-01-21 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| IESG | Responsible AD | Allison J. Mankin | |
| Send notices to | (None) |
RFC 3720
RFC 3720 iSCSI April 2004 Appendix C. Login Phase Examples In the first example, the initiator and target authenticate each other via Kerberos: I-> Login (CSG,NSG=0,1 T=1) InitiatorName=iqn.1999-07.com.os:hostid.77 TargetName=iqn.1999-07.com.example:diskarray.sn.88 AuthMethod=KRB5,SRP,None T-> Login (CSG,NSG=0,0 T=0) AuthMethod=KRB5 I-> Login (CSG,NSG=0,1 T=1) KRB_AP_REQ=<krb_ap_req> (krb_ap_req contains the Kerberos V5 ticket and authenticator with MUTUAL-REQUIRED set in the ap-options field) If the authentication is successful, the target proceeds with: T-> Login (CSG,NSG=0,1 T=1) KRB_AP_REP=<krb_ap_rep> (krb_ap_rep is the Kerberos V5 mutual authentication reply) If the authentication is successful, the initiator may proceed with: I-> Login (CSG,NSG=1,0 T=0) FirstBurstLength=8192 T-> Login (CSG,NSG=1,0 T=0) FirstBurstLength=4096 MaxBurstLength=8192 I-> Login (CSG,NSG=1,0 T=0) MaxBurstLength=8192 ... more iSCSI Operational Parameters T-> Login (CSG,NSG=1,0 T=0) ... more iSCSI Operational Parameters And at the end: I-> Login (CSG,NSG=1,3 T=1) optional iSCSI parameters T-> Login (CSG,NSG=1,3 T=1) "login accept" Satran, et al. Standards Track [Page 219] RFC 3720 iSCSI April 2004 If the initiator's authentication by the target is not successful, the target responds with: T-> Login "login reject" instead of the Login KRB_AP_REP message, and terminates the connection. If the target's authentication by the initiator is not successful, the initiator terminates the connection (without responding to the Login KRB_AP_REP message). In the next example only the initiator is authenticated by the target via Kerberos: I-> Login (CSG,NSG=0,1 T=1) InitiatorName=iqn.1999-07.com.os:hostid.77 TargetName=iqn.1999-07.com.example:diskarray.sn.88 AuthMethod=SRP,KRB5,None T-> Login-PR (CSG,NSG=0,0 T=0) AuthMethod=KRB5 I-> Login (CSG,NSG=0,1 T=1) KRB_AP_REQ=krb_ap_req (MUTUAL-REQUIRED not set in the ap-options field of krb_ap_req) If the authentication is successful, the target proceeds with: T-> Login (CSG,NSG=0,1 T=1) I-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters T-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters . . . T-> Login (CSG,NSG=1,3 T=1)"login accept" Satran, et al. Standards Track [Page 220] RFC 3720 iSCSI April 2004 In the next example, the initiator and target authenticate each other via SPKM1: I-> Login (CSG,NSG=0,1 T=1) InitiatorName=iqn.1999-07.com.os:hostid.77 TargetName=iqn.1999-07.com.example:diskarray.sn.88 AuthMethod=SPKM1,KRB5,None T-> Login (CSG,NSG=0,0 T=0) AuthMethod=SPKM1 I-> Login (CSG,NSG=0,0 T=0) SPKM_REQ=<spkm-req> (spkm-req is the SPKM-REQ token with the mutual-state bit in the options field of the REQ-TOKEN set) T-> Login (CSG,NSG=0,0 T=0) SPKM_REP_TI=<spkm-rep-ti> If the authentication is successful, the initiator proceeds: I-> Login (CSG,NSG=0,1 T=1) SPKM_REP_IT=<spkm-rep-it> If the authentication is successful, the target proceeds with: T-> Login (CSG,NSG=0,1 T=1) The initiator may proceed: I-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters T-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters And at the end: I-> Login (CSG,NSG=1,3 T=1) optional iSCSI parameters T-> Login (CSG,NSG=1,3 T=1) "login accept" If the target's authentication by the initiator is not successful, the initiator terminates the connection (without responding to the Login SPKM_REP_TI message). Satran, et al. Standards Track [Page 221] RFC 3720 iSCSI April 2004 If the initiator's authentication by the target is not successful, the target responds with: T-> Login "login reject" instead of the Login "proceed and change stage" message, and terminates the connection. In the next example, the initiator and target authenticate each other via SPKM2: I-> Login (CSG,NSG=0,0 T=0) InitiatorName=iqn.1999-07.com.os:hostid.77 TargetName=iqn.1999-07.com.example:diskarray.sn.88 AuthMethod=SPKM1,SPKM2 T-> Login-PR (CSG,NSG=0,0 T=0) AuthMethod=SPKM2 I-> Login (CSG,NSG=0,1 T=1) SPKM_REQ=<spkm-req> (spkm-req is the SPKM-REQ token with the mutual-state bit in the options field of the REQ-TOKEN not set) If the authentication is successful, the target proceeds with: T-> Login (CSG,NSG=0,1 T=1) The initiator may proceed: I-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters T-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters And at the end: I-> Login (CSG,NSG=1,3 T=1) optional iSCSI parameters T-> Login (CSG,NSG=1,3 T=1) "login accept" Satran, et al. Standards Track [Page 222] RFC 3720 iSCSI April 2004 In the next example, the initiator and target authenticate each other via SRP: I-> Login (CSG,NSG=0,1 T=1) InitiatorName=iqn.1999-07.com.os:hostid.77 TargetName=iqn.1999-07.com.example:diskarray.sn.88 AuthMethod=KRB5,SRP,None T-> Login-PR (CSG,NSG=0,0 T=0) AuthMethod=SRP I-> Login (CSG,NSG=0,0 T=0) SRP_U=<user> TargetAuth=Yes T-> Login (CSG,NSG=0,0 T=0) SRP_GROUP=SRP-1536,SRP-1024 SRP_s=<s> I-> Login (CSG,NSG=0,0 T=0) SRP_GROUP=SRP-1536 SRP_A=<A> T-> Login (CSG,NSG=0,0 T=0) SRP_B=<B> I-> Login (CSG,NSG=0,1 T=1) SRP_M=<M> If the initiator authentication is successful, the target proceeds: T-> Login (CSG,NSG=0,1 T=1) SRP_HM=<H(A | M | K)> Where N, g, s, A, B, M, and H(A | M | K) are defined in [RFC2945]. If the target authentication is not successful, the initiator terminates the connection; otherwise, it proceeds. I-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters T-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters Satran, et al. Standards Track [Page 223] RFC 3720 iSCSI April 2004 And at the end: I-> Login (CSG,NSG=1,3 T=1) optional iSCSI parameters T-> Login (CSG,NSG=1,3 T=1) "login accept" If the initiator authentication is not successful, the target responds with: T-> Login "login reject" Instead of the T-> Login SRP_HM=<H(A | M | K)> message and terminates the connection. In the next example, the initiator and target authenticate each other via SRP: I-> Login (CSG,NSG=0,1 T=1) InitiatorName=iqn.1999-07.com.os:hostid.77 TargetName=iqn.1999-07.com.example:diskarray.sn.88 AuthMethod=KRB5,SRP,None T-> Login-PR (CSG,NSG=0,0 T=0) AuthMethod=SRP I-> Login (CSG,NSG=0,0 T=0) SRP_U=<user> TargetAuth=No T-> Login (CSG,NSG=0,0 T=0) SRP_GROUP=SRP-1536 SRP_s=<s> I-> Login (CSG,NSG=0,0 T=0) SRP_GROUP=SRP-1536 SRP_A=<A> T-> Login (CSG,NSG=0,0 T=0) SRP_B=<B> I-> Login (CSG,NSG=0,1 T=1) SRP_M=<M> If the initiator authentication is successful, the target proceeds: T-> Login (CSG,NSG=0,1 T=1) Satran, et al. Standards Track [Page 224] RFC 3720 iSCSI April 2004 I-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters T-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters And at the end: I-> Login (CSG,NSG=1,3 T=1) optional iSCSI parameters T-> Login (CSG,NSG=1,3 T=1) "login accept" In the next example the initiator and target authenticate each other via CHAP: I-> Login (CSG,NSG=0,0 T=0) InitiatorName=iqn.1999-07.com.os:hostid.77 TargetName=iqn.1999-07.com.example:diskarray.sn.88 AuthMethod=KRB5,CHAP,None T-> Login-PR (CSG,NSG=0,0 T=0) AuthMethod=CHAP I-> Login (CSG,NSG=0,0 T=0) CHAP_A=<A1,A2> T-> Login (CSG,NSG=0,0 T=0) CHAP_A=<A1> CHAP_I=<I> CHAP_C=<C> I-> Login (CSG,NSG=0,1 T=1) CHAP_N=<N> CHAP_R=<R> CHAP_I=<I> CHAP_C=<C> Satran, et al. Standards Track [Page 225] RFC 3720 iSCSI April 2004 If the initiator authentication is successful, the target proceeds: T-> Login (CSG,NSG=0,1 T=1) CHAP_N=<N> CHAP_R=<R> If the target authentication is not successful, the initiator aborts the connection; otherwise, it proceeds. I-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters T-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters And at the end: I-> Login (CSG,NSG=1,3 T=1) optional iSCSI parameters T-> Login (CSG,NSG=1,3 T=1) "login accept" If the initiator authentication is not successful, the target responds with: T-> Login "login reject" Instead of the Login CHAP_R=<response> "proceed and change stage" message and terminates the connection. In the next example, only the initiator is authenticated by the target via CHAP: I-> Login (CSG,NSG=0,1 T=0) InitiatorName=iqn.1999-07.com.os:hostid.77 TargetName=iqn.1999-07.com.example:diskarray.sn.88 AuthMethod=KRB5,CHAP,None T-> Login-PR (CSG,NSG=0,0 T=0) AuthMethod=CHAP I-> Login (CSG,NSG=0,0 T=0) CHAP_A=<A1,A2> Satran, et al. Standards Track [Page 226] RFC 3720 iSCSI April 2004 T-> Login (CSG,NSG=0,0 T=0) CHAP_A=<A1> CHAP_I=<I> CHAP_C=<C> I-> Login (CSG,NSG=0,1 T=1) CHAP_N=<N> CHAP_R=<R> If the initiator authentication is successful, the target proceeds: T-> Login (CSG,NSG=0,1 T=1) I-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters T-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters And at the end: I-> Login (CSG,NSG=1,3 T=1) optional iSCSI parameters T-> Login (CSG,NSG=1,3 T=1) "login accept" In the next example, the initiator does not offer any security parameters. It therefore may offer iSCSI parameters on the Login PDU with the T bit set to 1, and the target may respond with a final Login Response PDU immediately: I-> Login (CSG,NSG=1,3 T=1) InitiatorName=iqn.1999-07.com.os:hostid.77 TargetName=iqn.1999-07.com.example:diskarray.sn.88 ... iSCSI parameters T-> Login (CSG,NSG=1,3 T=1) "login accept" ... ISCSI parameters In the next example, the initiator does offer security parameters on the Login PDU, but the target does not choose any (i.e., chooses the "None" values): I-> Login (CSG,NSG=0,1 T=1) InitiatorName=iqn.1999-07.com.os:hostid.77 TargetName=iqn.1999-07.com.example:diskarray.sn.88 AuthMethod=KRB5,SRP,None Satran, et al. Standards Track [Page 227] RFC 3720 iSCSI April 2004 T-> Login-PR (CSG,NSG=0,1 T=1) AuthMethod=None I-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters T-> Login (CSG,NSG=1,0 T=0) ... iSCSI parameters And at the end: I-> Login (CSG,NSG=1,3 T=1) optional iSCSI parameters T-> Login (CSG,NSG=1,3 T=1) "login accept" Satran, et al. Standards Track [Page 228] RFC 3720 iSCSI April 2004 Appendix D. SendTargets Operation To reduce the amount of configuration required on an initiator, iSCSI provides the SendTargets text request. The initiator uses the SendTargets request to get a list of targets to which it may have access, as well as the list of addresses (IP address and TCP port) on which these targets may be accessed. To make use of SendTargets, an initiator must first establish one of two types of sessions. If the initiator establishes the session using the key "SessionType=Discovery", the session is a discovery session, and a target name does not need to be specified. Otherwise, the session is a normal, operational session. The SendTargets command MUST only be sent during the Full Feature Phase of a normal or discovery session. A system that contains targets MUST support discovery sessions on each of its iSCSI IP address-port pairs, and MUST support the SendTargets command on the discovery session. In a discovery session, a target MUST return all path information (target name and IP address-port pairs and portal group tags) for the targets on the target network entity which the requesting initiator is authorized to access. A target MUST support the SendTargets command on operational sessions; these will only return path information about the target to which the session is connected, and do not need to return information about other target names that may be defined in the responding system. An initiator MAY make use of the SendTargets as it sees fit. A SendTargets command consists of a single Text request PDU. This PDU contains exactly one text key and value. The text key MUST be SendTargets. The expected response depends upon the value, as well as whether the session is a discovery or operational session. The value must be one of: All The initiator is requesting that information on all relevant targets known to the implementation be returned. This value MUST be supported on a discovery session, and MUST NOT be supported on an operational session. Satran, et al. Standards Track [Page 229] RFC 3720 iSCSI April 2004 <iSCSI-target-name> If an iSCSI target name is specified, the session should respond with addresses for only the named target, if possible. This value MUST be supported on discovery sessions. A discovery session MUST be capable of returning addresses for those targets that would have been returned had value=All had been designated. <nothing> The session should only respond with addresses for the target to which the session is logged in. This MUST be supported on operational sessions, and MUST NOT return targets other than the one to which the session is logged in. The response to this command is a text response that contains a list of zero or more targets and, optionally, their addresses. Each target is returned as a target record. A target record begins with the TargetName text key, followed by a list of TargetAddress text keys, and bounded by the end of the text response or the next TargetName key, which begins a new record. No text keys other than TargetName and TargetAddress are permitted within a SendTargets response. For the format of the TargetName, see Section 12.4 TargetName. In a discovery session, a target MAY respond to a SendTargets request with its complete list of targets, or with a list of targets that is based on the name of the initiator logged in to the session. A SendTargets response MUST NOT contain target names if there are no targets for the requesting initiator to access. Each target record returned includes zero or more TargetAddress fields. Each target record starts with one text key of the form: TargetName=<target-name-goes-here> Followed by zero or more address keys of the form: TargetAddress=<hostname-or-ipaddress>[:<tcp-port>], <portal-group-tag> The hostname-or-ipaddress contains a domain name, IPv4 address, or IPv6 address, as specified for the TargetAddress key. Satran, et al. Standards Track [Page 230] RFC 3720 iSCSI April 2004 A hostname-or-ipaddress duplicated in TargetAddress responses for a given node (the port is absent or equal) would probably indicate that multiple address families are in use at once (IPV6 and IPV4). Each TargetAddress belongs to a portal group, identified by its numeric portal group tag (as in Section 12.9 TargetPortalGroupTag). The iSCSI target name, together with this tag, constitutes the SCSI port identifier; the tag only needs to be unique within a given target's name list of addresses. Multiple-connection sessions can span iSCSI addresses that belong to the same portal group. Multiple-connection sessions cannot span iSCSI addresses that belong to different portal groups. If a SendTargets response reports an iSCSI address for a target, it SHOULD also report all other addresses in its portal group in the same response. A SendTargets text response can be longer than a single Text Response PDU, and makes use of the long text responses as specified. After obtaining a list of targets from the discovery target session, an iSCSI initiator may initiate new sessions to log in to the discovered targets for full operation. The initiator MAY keep the discovery session open, and MAY send subsequent SendTargets commands to discover new targets. Examples: This example is the SendTargets response from a single target that has no other interface ports. Initiator sends text request that contains: SendTargets=All Target sends a text response that contains: TargetName=iqn.1993-11.com.example:diskarray.sn.8675309 All the target had to return in the simple case was the target name. It is assumed by the initiator that the IP address and TCP port for this target are the same as used on the current connection to the default iSCSI target. Satran, et al. Standards Track [Page 231] RFC 3720 iSCSI April 2004 The next example has two internal iSCSI targets, each accessible via two different ports with different IP addresses. The following is the text response: TargetName=iqn.1993-11.com.example:diskarray.sn.8675309 TargetAddress=10.1.0.45:3000,1 TargetAddress=10.1.1.45:3000,2 TargetName=iqn.1993-11.com.example:diskarray.sn.1234567 TargetAddress=10.1.0.45:3000,1 TargetAddress=10.1.1.45:3000,2 Both targets share both addresses; the multiple addresses are likely used to provide multi-path support. The initiator may connect to either target name on either address. Each of the addresses has its own portal group tag; they do not support spanning multiple-connection sessions with each other. Keep in mind that the portal group tags for the two named targets are independent of one another; portal group "1" on the first target is not necessarily the same as portal group "1" on the second target. In the above example, a DNS host name or an IPv6 address could have been returned instead of an IPv4 address. The next text response shows a target that supports spanning sessions across multiple addresses, and further illustrates the use of the portal group tags: TargetName=iqn.1993-11.com.example:diskarray.sn.8675309 TargetAddress=10.1.0.45:3000,1 TargetAddress=10.1.1.46:3000,1 TargetAddress=10.1.0.47:3000,2 TargetAddress=10.1.1.48:3000,2 TargetAddress=10.1.1.49:3000,3 In this example, any of the target addresses can be used to reach the same target. A single-connection session can be established to any of these TCP addresses. A multiple-connection session could span addresses .45 and .46 or .47 and .48, but cannot span any other combination. A TargetAddress with its own tag (.49) cannot be combined with any other address within the same session. This SendTargets response does not indicate whether .49 supports multiple connections per session; it is communicated via the MaxConnections text key upon login to the target. Satran, et al. Standards Track [Page 232] RFC 3720 iSCSI April 2004 Appendix E. Algorithmic Presentation of Error Recovery Classes This appendix illustrates the error recovery classes using a pseudo-programming-language. The procedure names are chosen to be obvious to most implementers. Each of the recovery classes described has initiator procedures as well as target procedures. These algorithms focus on outlining the mechanics of error recovery classes, and do not exhaustively describe all other aspects/cases. Examples of this approach are: - Handling for only certain Opcode types is shown. - Only certain reason codes (e.g., Recovery in Logout command) are outlined. - Resultant cases, such as recovery of Synchronization on a header digest error are considered out-of-scope in these algorithms. In this particular example, a header digest error may lead to connection recovery if some type of sync and steering layer is not implemented. These algorithms strive to convey the iSCSI error recovery concepts in the simplest terms, and are not designed to be optimal. E.1. General Data Structure and Procedure Description This section defines the procedures and data structures that are commonly used by all the error recovery algorithms. The structures may not be the exhaustive representations of what is required for a typical implementation. Data structure definitions - struct TransferContext { int TargetTransferTag; int ExpectedDataSN; }; struct TCB { /* task control block */ Boolean SoFarInOrder; int ExpectedDataSN; /* used for both R2Ts, and Data */ int MissingDataSNList[MaxMissingDPDU]; Boolean FbitReceived; Boolean StatusXferd; Boolean CurrentlyAllegiant; int ActiveR2Ts; int Response; char *Reason; Satran, et al. Standards Track [Page 233] RFC 3720 iSCSI April 2004 struct TransferContext TransferContextList[MaxOutStandingR2T]; int InitiatorTaskTag; int CmdSN; int SNACK_Tag; }; struct Connection { struct Session SessionReference; Boolean SoFarInOrder; int CID; int State; int CurrentTimeout; int ExpectedStatSN; int MissingStatSNList[MaxMissingSPDU]; Boolean PerformConnectionCleanup; }; struct Session { int NumConnections; int CmdSN; int Maxconnections; int ErrorRecoveryLevel; struct iSCSIEndpoint OtherEndInfo; struct Connection ConnectionList[MaxSupportedConns]; }; Procedure descriptions - Receive-a-In-PDU(transport connection, inbound PDU); check-basic-validity(inbound PDU); Start-Timer(timeout handler, argument, timeout value); Build-And-Send-Reject(transport connection, bad PDU, reason code); E.2. Within-command Error Recovery Algorithms E.2.1. Procedure Descriptions Recover-Data-if-Possible(last required DataSN, task control block); Build-And-Send-DSnack(task control block); Build-And-Send-RDSnack(task control block); Build-And-Send-Abort(task control block); SCSI-Task-Completion(task control block); Build-And-Send-A-Data-Burst(transport connection, data-descriptor, task control block); Satran, et al. Standards Track [Page 234] RFC 3720 iSCSI April 2004 Build-And-Send-R2T(transport connection, data-descriptor, task control block); Build-And-Send-Status(transport connection, task control block); Transfer-Context-Timeout-Handler(transfer context); Notes: - One procedure used in this section: Handle-Status-SNACK- request is defined in Within-connection recovery algorithms. - The Response processing pseudo-code, shown in the target algorithms, applies to all solicited PDUs that carry StatSN - SCSI Response, Text Response etc. E.2.2. Initiator Algorithms Recover-Data-if-Possible(LastRequiredDataSN, TCB) { if (operational ErrorRecoveryLevel > 0) { if (# of missing PDUs is trackable) { Note the missing DataSNs in TCB. if (the task spanned a change in MaxRecvDataSegmentLength) { if (TCB.StatusXferd is TRUE) drop the status PDU; Build-And-Send-RDSnack(TCB); } else { Build-And-Send-DSnack(TCB); } } else { TCB.Reason = "Protocol service CRC error"; } } else { TCB.Reason = "Protocol service CRC error"; } if (TCB.Reason == "Protocol service CRC error") { Clear the missing PDU list in the TCB. if (TCB.StatusXferd is not TRUE) Build-And-Send-Abort(TCB); } } Receive-a-In-PDU(Connection, CurrentPDU) { check-basic-validity(CurrentPDU); if (Header-Digest-Bad) discard, return; Retrieve TCB for CurrentPDU.InitiatorTaskTag. Satran, et al. Standards Track [Page 235] RFC 3720 iSCSI April 2004 if ((CurrentPDU.type == Data) or (CurrentPDU.type = R2T)) { if (Data-Digest-Bad for Data) { send-data-SNACK = TRUE; LastRequiredDataSN = CurrentPDU.DataSN; } else { if (TCB.SoFarInOrder = TRUE) { if (current DataSN is expected) { Increment TCB.ExpectedDataSN. } else { TCB.SoFarInOrder = FALSE; send-data-SNACK = TRUE; } } else { if (current DataSN was considered missing) { remove current DataSN from missing PDU list. } else if (current DataSN is higher than expected) { send-data-SNACK = TRUE; } else { discard, return; } Adjust TCB.ExpectedDataSN if appropriate. } LastRequiredDataSN = CurrentPDU.DataSN - 1; } if (send-data-SNACK is TRUE and task is not already considered failed) { Recover-Data-if-Possible(LastRequiredDataSN, TCB); } if (missing data PDU list is empty) { TCB.SoFarInOrder = TRUE; } if (CurrentPDU.type == R2T) { Increment ActiveR2Ts for this task. Create a data-descriptor for the data burst. Build-And-Send-A-Data-Burst(Connection, data-descriptor, TCB); } } else if (CurrentPDU.type == Response) { if (Data-Digest-Bad) { send-status-SNACK = TRUE; } else { TCB.StatusXferd = TRUE; Store the status information in TCB. Satran, et al. Standards Track [Page 236] RFC 3720 iSCSI April 2004 if (ExpDataSN does not match) { TCB.SoFarInOrder = FALSE; Recover-Data-if-Possible(current DataSN, TCB); } if (missing data PDU list is empty) { TCB.SoFarInOrder = TRUE; } } } else { /* REST UNRELATED TO WITHIN-COMMAND-RECOVERY, NOT SHOWN */ } if ((TCB.SoFarInOrder == TRUE) and (TCB.StatusXferd == TRUE)) { SCSI-Task-Completion(TCB); } } E.2.3. Target Algorithms Receive-a-In-PDU(Connection, CurrentPDU) { check-basic-validity(CurrentPDU); if (Header-Digest-Bad) discard, return; Retrieve TCB for CurrentPDU.InitiatorTaskTag. if (CurrentPDU.type == Data) { Retrieve TContext from CurrentPDU.TargetTransferTag; if (Data-Digest-Bad) { Build-And-Send-Reject(Connection, CurrentPDU, Payload-Digest-Error); Note the missing data PDUs in MissingDataRange[]. send-recovery-R2T = TRUE; } else { if (current DataSN is not expected) { Note the missing data PDUs in MissingDataRange[]. send-recovery-R2T = TRUE; } if (CurrentPDU.Fbit == TRUE) { if (current PDU is solicited) { Decrement TCB.ActiveR2Ts. } if ((current PDU is unsolicited and data received is less than I/O length and data received is less than FirstBurstLength) or (current PDU is solicited and the length of this burst is less than expected)) { send-recovery-R2T = TRUE; Note the missing data in MissingDataRange[]. } Satran, et al. Standards Track [Page 237] RFC 3720 iSCSI April 2004 } } Increment TContext.ExpectedDataSN. if (send-recovery-R2T is TRUE and task is not already considered failed) { if (operational ErrorRecoveryLevel > 0) { Increment TCB.ActiveR2Ts. Create a data-descriptor for the data burst from MissingDataRange. Build-And-Send-R2T(Connection, data-descriptor, TCB); } else { if (current PDU is the last unsolicited) TCB.Reason = "Not enough unsolicited data"; else TCB.Reason = "Protocol service CRC error"; } } if (TCB.ActiveR2Ts == 0) { Build-And-Send-Status(Connection, TCB); } } else if (CurrentPDU.type == SNACK) { snack-failure = FALSE; if (operational ErrorRecoveryLevel > 0) { if (CurrentPDU.type == Data/R2T) { if (the request is satisfiable) { if (request for Data) { Create a data-descriptor for the data burst from BegRun and RunLength. Build-And-Send-A-Data-Burst(Connection, data-descriptor, TCB); } else { /* R2T */ Create a data-descriptor for the data burst from BegRun and RunLength. Build-And-Send-R2T(Connection, data-descriptor, TCB); } } else { snack-failure = TRUE; } } else if (CurrentPDU.type == status) { Handle-Status-SNACK-request(Connection, CurrentPDU); } else if (CurrentPDU.type == DataACK) { Consider all data upto CurrentPDU.BegRun as acknowledged. Free up the retransmission resources for that data. } else if (CurrentPDU.type == R-Data SNACK) { Satran, et al. Standards Track [Page 238] RFC 3720 iSCSI April 2004 Create a data descriptor for a data burst covering all unacknowledged data. Build-And-Send-A-Data-Burst(Connection, data-descriptor, TCB); TCB.SNACK_Tag = CurrentPDU.SNACK_Tag; if (there's no more data to send) { Build-And-Send-Status(Connection, TCB); } } } else { /* operational ErrorRecoveryLevel = 0 */ snack-failure = TRUE; } if (snack-failure == TRUE) { Build-And-Send-Reject(Connection, CurrentPDU, SNACK-Reject); if (TCB.StatusXferd != TRUE) { TCB.Reason = "SNACK Rejected"; Build-And-Send-Status(Connection, TCB); } } } else { /* REST UNRELATED TO WITHIN-COMMAND-RECOVERY, NOT SHOWN */ } } Transfer-Context-Timeout-Handler(TContext) { Retrieve TCB and Connection from TContext. Decrement TCB.ActiveR2Ts. if (operational ErrorRecoveryLevel > 0 and task is not already considered failed) { Note the missing data PDUs in MissingDataRange[]. Create a data-descriptor for the data burst from MissingDataRange[]. Build-And-Send-R2T(Connection, data-descriptor, TCB); } else { TCB.Reason = "Protocol service CRC error"; if (TCB.ActiveR2Ts = 0) { Build-And-Send-Status(Connection, TCB); } } } Satran, et al. Standards Track [Page 239] RFC 3720 iSCSI April 2004 E.3. Within-connection Recovery Algorithms E.3.1. Procedure Descriptions Procedure descriptions: Recover-Status-if-Possible(transport connection, currently received PDU); Evaluate-a-StatSN(transport connection, currently received PDU); Retransmit-Command-if-Possible(transport connection, CmdSN); Build-And-Send-SSnack(transport connection); Build-And-Send-Command(transport connection, task control block); Command-Acknowledge-Timeout-Handler(task control block); Status-Expect-Timeout-Handler(transport connection); Build-And-Send-Nop-Out(transport connection); Handle-Status-SNACK-request(transport connection, status SNACK PDU); Retransmit-Status-Burst(status SNACK, task control block); Is-Acknowledged(beginning StatSN, run length); Implementation-specific tunables: InitiatorProactiveSNACKEnabled Notes: - The initiator algorithms only deal with unsolicited Nop-In PDUs for generating status SNACKs. A solicited Nop-In PDU has an assigned StatSN, which, when out of order, could trigger the out of order StatSN handling in Within-command algorithms, again leading to Recover-Status-if-Possible. - The pseudo-code shown may result in the retransmission of unacknowledged commands in more cases than necessary. This will not, however, affect the correctness of the operation because the target is required to discard the duplicate CmdSNs. - The procedure Build-And-Send-Async is defined in the Connection recovery algorithms. - The procedure Status-Expect-Timeout-Handler describes how initiators may proactively attempt to retrieve the Status if they so choose. This procedure is assumed to be triggered much before the standard ULP timeout. Satran, et al. Standards Track [Page 240] RFC 3720 iSCSI April 2004 E.3.2. Initiator Algorithms Recover-Status-if-Possible(Connection, CurrentPDU) { if ((Connection.state == LOGGED_IN) and connection is not already considered failed) { if (operational ErrorRecoveryLevel > 0) { if (# of missing PDUs is trackable) { Note the missing StatSNs in Connection that were not already requested with SNACK; Build-And-Send-SSnack(Connection); } else { Connection.PerformConnectionCleanup = TRUE; } } else { Connection.PerformConnectionCleanup = TRUE; } if (Connection.PerformConnectionCleanup == TRUE) { Start-Timer(Connection-Cleanup-Handler, Connection, 0); } } } Retransmit-Command-if-Possible(Connection, CmdSN) { if (operational ErrorRecoveryLevel > 0) { Retrieve the InitiatorTaskTag, and thus TCB for the CmdSN. Build-And-Send-Command(Connection, TCB); } } Evaluate-a-StatSN(Connection, CurrentPDU) { send-status-SNACK = FALSE; if (Connection.SoFarInOrder == TRUE) { if (current StatSN is the expected) { Increment Connection.ExpectedStatSN. } else { Connection.SoFarInOrder = FALSE; send-status-SNACK = TRUE; } } else { if (current StatSN was considered missing) { remove current StatSN from the missing list. } else { if (current StatSN is higher than expected){ send-status-SNACK = TRUE; Satran, et al. Standards Track [Page 241] RFC 3720 iSCSI April 2004 } else { send-status-SNACK = FALSE; discard the PDU; } } Adjust Connection.ExpectedStatSN if appropriate. if (missing StatSN list is empty) { Connection.SoFarInOrder = TRUE; } } return send-status-SNACK; } Receive-a-In-PDU(Connection, CurrentPDU) { check-basic-validity(CurrentPDU); if (Header-Digest-Bad) discard, return; Retrieve TCB for CurrentPDU.InitiatorTaskTag. if (CurrentPDU.type == Nop-In) { if (the PDU is unsolicited) { if (current StatSN is not expected) { Recover-Status-if-Possible(Connection, CurrentPDU); } if (current ExpCmdSN is not Session.CmdSN) { Retransmit-Command-if-Possible(Connection, CurrentPDU.ExpCmdSN); } } } else if (CurrentPDU.type == Reject) { if (it is a data digest error on immediate data) { Retransmit-Command-if-Possible(Connection, CurrentPDU.BadPDUHeader.CmdSN); } } else if (CurrentPDU.type == Response) { send-status-SNACK = Evaluate-a-StatSN(Connection, CurrentPDU); if (send-status-SNACK == TRUE) Recover-Status-if-Possible(Connection, CurrentPDU); } else { /* REST UNRELATED TO WITHIN-CONNECTION-RECOVERY, * NOT SHOWN */ } } Command-Acknowledge-Timeout-Handler(TCB) { Retrieve the Connection for TCB. Retransmit-Command-if-Possible(Connection, TCB.CmdSN); Satran, et al. Standards Track [Page 242] RFC 3720 iSCSI April 2004 } Status-Expect-Timeout-Handler(Connection) { if (operational ErrorRecoveryLevel > 0) { Build-And-Send-Nop-Out(Connection); } else if (InitiatorProactiveSNACKEnabled){ if ((Connection.state == LOGGED_IN) and connection is not already considered failed) { Build-And-Send-SSnack(Connection); } } } E.3.3. Target Algorithms Handle-Status-SNACK-request(Connection, CurrentPDU) { if (operational ErrorRecoveryLevel > 0) { if (request for an acknowledged run) { Build-And-Send-Reject(Connection, CurrentPDU, Protocol-Error); } else if (request for an untransmitted run) { discard, return; } else { Retransmit-Status-Burst(CurrentPDU, TCB); } else { Build-And-Send-Async(Connection, DroppedConnection, DefaultTime2Wait, DefaultTime2Retain); } } E.4. Connection Recovery Algorithms E.4.1. Procedure Descriptions Build-And-Send-Async(transport connection, reason code, minimum time, maximum time); Pick-A-Logged-In-Connection(session); Build-And-Send-Logout(transport connection, logout connection identifier, reason code); PerformImplicitLogout(transport connection, logout connection identifier, target information); PerformLogin(transport connection, target information); CreateNewTransportConnection(target information); Build-And-Send-Command(transport connection, task control block); Connection-Cleanup-Handler(transport connection); Satran, et al. Standards Track [Page 243] RFC 3720 iSCSI April 2004 Connection-Resource-Timeout-Handler(transport connection); Quiesce-And-Prepare-for-New-Allegiance(session, task control block); Build-And-Send-Logout-Response(transport connection, CID of connection in recovery, reason code); Build-And-Send-TaskMgmt-Response(transport connection, task mgmt command PDU, response code); Establish-New-Allegiance(task control block, transport connection); Schedule-Command-To-Continue(task control block); Notes: - Transport exception conditions, such as unexpected connection termination, connection reset, and hung connection while the connection is in the full-feature phase, are all assumed to be asynchronously signaled to the iSCSI layer using the Transport_Exception_Handler procedure. E.4.2. Initiator Algorithms Receive-a-In-PDU(Connection, CurrentPDU) { check-basic-validity(CurrentPDU); if (Header-Digest-Bad) discard, return; Retrieve TCB from CurrentPDU.InitiatorTaskTag. if (CurrentPDU.type == Async) { if (CurrentPDU.AsyncEvent == ConnectionDropped) { Retrieve the AffectedConnection for CurrentPDU.Parameter1. AffectedConnection.CurrentTimeout = CurrentPDU.Parameter3; AffectedConnection.State = CLEANUP_WAIT; Start-Timer(Connection-Cleanup-Handler, AffectedConnection, CurrentPDU.Parameter2); } else if (CurrentPDU.AsyncEvent == LogoutRequest)) { AffectedConnection = Connection; AffectedConnection.State = LOGOUT_REQUESTED; AffectedConnection.PerformConnectionCleanup = TRUE; AffectedConnection.CurrentTimeout = CurrentPDU.Parameter3; Start-Timer(Connection-Cleanup-Handler, AffectedConnection, 0); } else if (CurrentPDU.AsyncEvent == SessionDropped)) { for (each Connection) { Connection.State = CLEANUP_WAIT; Connection.CurrentTimeout = CurrentPDU.Parameter3; Satran, et al. Standards Track [Page 244] RFC 3720 iSCSI April 2004 Start-Timer(Connection-Cleanup-Handler, Connection, CurrentPDU.Parameter2); } Session.state = FAILED; } } else if (CurrentPDU.type == LogoutResponse) { Retrieve the CleanupConnection for CurrentPDU.CID. if (CurrentPDU.Response = failure) { CleanupConnection.State = CLEANUP_WAIT; } else { CleanupConnection.State = FREE; } } else if (CurrentPDU.type == LoginResponse) { if (this is a response to an implicit Logout) { Retrieve the CleanupConnection. if (successful) { CleanupConnection.State = FREE; Connection.State = LOGGED_IN; } else { CleanupConnection.State = CLEANUP_WAIT; DestroyTransportConnection(Connection); } } } else { /* REST UNRELATED TO CONNECTION-RECOVERY, * NOT SHOWN */ } if (CleanupConnection.State == FREE) { for (each command that was active on CleanupConnection) { /* Establish new connection allegiance */ NewConnection = Pick-A-Logged-In-Connection(Session); Build-And-Send-Command(NewConnection, TCB); } } } Connection-Cleanup-Handler(Connection) { Retrieve Session from Connection. if (Connection can still exchange iSCSI PDUs) { NewConnection = Connection; } else { Start-Timer(Connection-Resource-Timeout-Handler, Connection, Connection.CurrentTimeout); if (there are other logged-in connections) { NewConnection = Pick-A-Logged-In- Connection(Session); } else { NewConnection = Satran, et al. Standards Track [Page 245] RFC 3720 iSCSI April 2004 CreateTransportConnection(Session.OtherEndInfo); Initiate an implicit Logout on NewConnection for Connection.CID. return; } } Build-And-Send-Logout(NewConnection, Connection.CID, RecoveryRemove); } Transport_Exception_Handler(Connection) { Connection.PerformConnectionCleanup = TRUE; if (the event is an unexpected transport disconnect) { Connection.State = CLEANUP_WAIT; Connection.CurrentTimeout = DefaultTime2Retain; Start-Timer(Connection-Cleanup-Handler, Connection, DefaultTime2Wait); } else { Connection.State = FREE; } } E.4.3. Target Algorithms Receive-a-In-PDU(Connection, CurrentPDU) { check-basic-validity(CurrentPDU); if (Header-Digest-Bad) discard, return; else if (Data-Digest-Bad) { Build-And-Send-Reject(Connection, CurrentPDU, Payload-Digest-Error); discard, return; } Retrieve TCB and Session. if (CurrentPDU.type == Logout) { if (CurrentPDU.ReasonCode = RecoveryRemove) { Retrieve the CleanupConnection from CurrentPDU.CID). for (each command active on CleanupConnection) { Quiesce-And-Prepare-for-New-Allegiance(Session, TCB); TCB.CurrentlyAllegiant = FALSE; } Cleanup-Connection-State(CleanupConnection); if ((quiescing successful) and (cleanup successful)) { Build-And-Send-Logout-Response(Connection, CleanupConnection.CID, Success); } else { Build-And-Send-Logout-Response(Connection, Satran, et al. Standards Track [Page 246] RFC 3720 iSCSI April 2004 CleanupConnection.CID, Failure); } } } else if ((CurrentPDU.type == Login) and operational ErrorRecoveryLevel == 2) { Retrieve the CleanupConnection from CurrentPDU.CID). for (each command active on CleanupConnection) { Quiesce-And-Prepare-for-New-Allegiance(Session, TCB); TCB.CurrentlyAllegiant = FALSE; } Cleanup-Connection-State(CleanupConnection); if ((quiescing successful) and (cleanup successful)) { Continue with the rest of the Login processing; } else { Build-And-Send-Login-Response(Connection, CleanupConnection.CID, Target Error); } } } else if (CurrentPDU.type == TaskManagement) { if (CurrentPDU.function == "TaskReassign") { if (Session.ErrorRecoveryLevel < 2) { Build-And-Send-TaskMgmt-Response(Connection, CurrentPDU, "Allegiance reassignment not supported"); } else if (task is not found) { Build-And-Send-TaskMgmt-Response(Connection, CurrentPDU, "Task not in task set"); } else if (task is currently allegiant) { Build-And-Send-TaskMgmt-Response(Connection, CurrentPDU, "Task still allegiant"); } else { Establish-New-Allegiance(TCB, Connection); TCB.CurrentlyAllegiant = TRUE; Schedule-Command-To-Continue(TCB); } } } else { /* REST UNRELATED TO CONNECTION-RECOVERY, * NOT SHOWN */ } } Transport_Exception_Handler(Connection) { Connection.PerformConnectionCleanup = TRUE; if (the event is an unexpected transport disconnect) { Connection.State = CLEANUP_WAIT; Start-Timer(Connection-Resource-Timeout-Handler, Satran, et al. Standards Track [Page 247] RFC 3720 iSCSI April 2004 Connection, (DefaultTime2Wait+DefaultTime2Retain)); if (this Session has full-feature phase connections left) { DifferentConnection = Pick-A-Logged-In-Connection(Session); Build-And-Send-Async(DifferentConnection, DroppedConnection, DefaultTime2Wait, DefaultTime2Retain); } } else { Connection.State = FREE; } } Satran, et al. Standards Track [Page 248] RFC 3720 iSCSI April 2004 Appendix F. Clearing Effects of Various Events on Targets F.1. Clearing Effects on iSCSI Objects The following tables describe the target behavior on receiving the events specified in the rows of the table. The second table is an extension of the first table and defines clearing actions for more objects on the same events. The legend is: Y = Yes (cleared/discarded/reset on the event specified in the row). Unless otherwise noted, the clearing action is only applicable for the issuing initiator port. N = No (not affected on the event specified in the row, i.e., stays at previous value). NA = Not Applicable or Not Defined. Satran, et al. Standards Track [Page 249] RFC 3720 iSCSI April 2004 +-----+-----+-----+-----+-----+ |IT(1)|IC(2)|CT(5)|ST(6)|PP(7)| +---------------------+-----+-----+-----+-----+-----+ |connection failure(8)|Y |Y |N |N |Y | +---------------------+-----+-----+-----+-----+-----+ |connection state |NA |NA |Y |N |NA | |timeout (9) | | | | | | +---------------------+-----+-----+-----+-----+-----+ |session timeout/ |Y |Y |Y |Y |Y(14)| |closure/reinstatement| | | | | | |(10) | | | | | | +---------------------+-----+-----+-----+-----+-----+ |session continuation |NA |NA |N(11)|N |NA | |(12) | | | | | | +---------------------+-----+-----+-----+-----+-----+ |successful connection|Y |Y |Y |N |Y(13)| |close logout | | | | | | +---------------------+-----+-----+-----+-----+-----+ |session failure (18) |Y |Y |N |N |Y | +---------------------+-----+-----+-----+-----+-----+ |successful recovery |Y |Y |N |N |Y(13)| |Logout | | | | | | +---------------------+-----+-----+-----+-----+-----+ |failed Logout |Y |Y |N |N |Y | +---------------------+-----+-----+-----+-----+-----+ |connection Login |NA |NA |NA |Y(15)|NA | |(leading) | | | | | | +---------------------+-----+-----+-----+-----+-----+ |connection Login |NA |NA |N(11)|N |Y | |(non-leading) | | | | | | +---------------------+-----+-----+-----+-----+-----+ |target cold reset(16)|Y |Y |Y |Y |Y | +---------------------+-----+-----+-----+-----+-----+ |target warm reset(16)|Y |Y |Y |Y |Y | +---------------------+-----+-----+-----+-----+-----+ |LU reset(19) |Y |Y |Y |Y |Y | +---------------------+-----+-----+-----+-----+-----+ |powercycle(16) |Y |Y |Y |Y |Y | +---------------------+-----+-----+-----+-----+-----+ 1. Incomplete TTTs - Target Transfer Tags on which the target is still expecting PDUs to be received. Examples include TTTs received via R2T, NOP-IN, etc. 2. Immediate Commands - immediate commands, but waiting for execution on a target. For example, Abort Task Set. Satran, et al. Standards Track [Page 250] RFC 3720 iSCSI April 2004 5. Connection Tasks - tasks that are active on the iSCSI connection in question. 6. Session Tasks - tasks that are active on the entire iSCSI session. A union of "connection tasks" on all participating connections. 7. Partial PDUs (if any) - PDUs that are partially sent and waiting for transport window credit to complete the transmission. 8. Connection failure is a connection exception condition - one of the transport connections shutdown, transport connections reset, or transport connections timed out, which abruptly terminated the iSCSI full-feature phase connection. A connection failure always takes the connection state machine to the CLEANUP_WAIT state. 9. Connection state timeout happens if a connection spends more time that agreed upon during Login negotiation in the CLEANUP_WAIT state, and this takes the connection to the FREE state (M1 transition in connection cleanup state diagram). 10. These are defined in Section 5.3.5 Session Reinstatement, Closure, and Timeout. 11. This clearing effect is "Y" only if it is a connection reinstatement and the operational ErrorRecoveryLevel is less than 2. 12. Session continuation is defined in Section 5.3.6 Session Continuation and Failure. 13. This clearing effect is only valid if the connection is being logged out on a different connection and when the connection being logged out on the target may have some partial PDUs pending to be sent. In all other cases, the effect is "NA". 14. This clearing effect is only valid for a "close the session" logout in a multi-connection session. In all other cases, the effect is "NA". 15. Only applicable if this leading connection login is a session reinstatement. If this is not the case, it is "NA". 16. This operation affects all logged-in initiators. 18. Session failure is defined in Section 5.3.6 Session Continuation and Failure. Satran, et al. Standards Track [Page 251] RFC 3720 iSCSI April 2004 19. This operation affects all logged-in initiators and the clearing effects are only applicable to the LU being reset. +-----+-----+-----+-----+-----+ |DC(1)|DD(2)|SS(3)|CS(4)|DS(5)| +---------------------+-----+-----+-----+-----+-----+ |connection failure |N |Y |N |N |N | +---------------------+-----+-----+-----+-----+-----+ |connection state |Y |NA |Y |N |NA | |timeout | | | | | | +---------------------+-----+-----+-----+-----+-----+ |session timeout/ |Y |Y |Y(7) |Y |NA | |closure/reinstatement| | | | | | +---------------------+-----+-----+-----+-----+-----+ |session continuation |N(11)|NA*12|NA |N |NA*13| +---------------------+-----+-----+-----+-----+-----+ |successful connection|Y |Y |Y |N |NA | |close Logout | | | | | | +---------------------+-----+-----+-----+-----+-----+ |session failure |N |Y |N |N |N | +---------------------+-----+-----+-----+-----+-----+ |successful recovery |Y |Y |Y |N |N | |Logout | | | | | | +---------------------+-----+-----+-----+-----+-----+ |failed Logout |N |Y(9) |N |N |N | +---------------------+-----+-----+-----+-----+-----+ |connection Login |NA |NA |N(8) |N(8) |NA | |(leading | | | | | | +---------------------+-----+-----+-----+-----+-----+ |connection Login |N(11)|NA*12|N(8) |N |NA*13| |(non-leading) | | | | | | +---------------------+-----+-----+-----+-----+-----+ |target cold reset |Y |Y |Y |Y(10)|NA | +---------------------+-----+-----+-----+-----+-----+ |target warm reset |Y |Y |N |N |NA | +---------------------+-----+-----+-----+-----+-----+ |LU reset |N |Y |N |N |N | +---------------------+-----+-----+-----+-----+-----+ |powercycle |Y |Y |Y |Y(10)|NA | +---------------------+-----+-----+-----+-----+-----+ 1. Discontiguous Commands - commands allegiant to the connection in question and waiting to be reordered in the iSCSI layer. All "Y"s in this column assume that the task causing the event (if indeed the event is the result of a task) is issued as an immediate command, because the discontiguities can be ahead of the task. Satran, et al. Standards Track [Page 252] RFC 3720 iSCSI April 2004 2. Discontiguous Data - data PDUs received for the task in question and waiting to be reordered due to prior discontiguities in DataSN. 3. StatSN 4. CmdSN 5. DataSN 7. It clears the StatSN on all the connections. 8. This sequence number is instantiated on this event. 9. A logout failure drives the connection state machine to the CLEANUP_WAIT state, similar to the connection failure event. Hence, it has a similar effect on this and several other protocol aspects. 10. This is cleared by virtue of the fact that all sessions with all initiators are terminated. 11. This clearing effect is "Y" if it is a connection reinstatement. 12. This clearing effect is "Y" only if it is a connection reinstatement and the operational ErrorRecoveryLevel is 2. 13. This clearing effect is "N" only if it is a connection reinstatement and the operational ErrorRecoveryLevel is 2. F.2. Clearing Effects on SCSI Objects The only iSCSI protocol action that can effect clearing actions on SCSI objects is the "I_T nexus loss" notification (Section 4.3.5.1 Loss of Nexus notification). [SPC3] describes the clearing effects of this notification on a variety of SCSI attributes. In addition, SCSI standards documents (such as [SAM2] and [SBC]) define additional clearing actions that may take place for several SCSI objects on SCSI events such as LU resets and power-on resets. Since iSCSI defines a target cold reset as a protocol-equivalent to a target power-cycle, the iSCSI target cold reset must also be considered as the power-on reset event in interpreting the actions defined in the SCSI standards. When the iSCSI session is reconstructed (between the same SCSI ports with the same nexus identifier) reestablishing the same I_T nexus, all SCSI objects that are defined to not clear on the "I_T nexus loss" notification event, such as persistent reservations, are automatically associated to this new session. Satran, et al. Standards Track [Page 253] RFC 3720 iSCSI April 2004 Acknowledgements This protocol was developed by a design team that, in addition to the authors, included Daniel Smith, Ofer Biran, Jim Hafner and John Hufferd (IBM), Mark Bakke (Cisco), Randy Haagens (HP), Matt Wakeley (Agilent, now Sierra Logic), Luciano Dalle Ore (Quantum), and Paul Von Stamwitz (Adaptec, now TrueSAN Networks). Furthermore, a large group of people contributed to this work through their review, comments, and valuable insights. We are grateful to all of them. We especially thank those people who found the time and patience to take part in our weekly phone conferences and intermediate meetings in Almaden and Haifa, which helped shape this document: Prasenjit Sarkar, Meir Toledano, John Dowdy, Steve Legg, Alain Azagury (IBM), Dave Nagle (CMU), David Black (EMC), John Matze (Veritas - now Okapi Software), Steve DeGroote, Mark Schrandt (Cisco), Gabi Hecht (Gadzoox), Robert Snively and Brian Forbes (Brocade), Nelson Nachum (StorAge), and Uri Elzur (Broadcom). Many others helped edit and improve this document within the IPS working group. We are especially grateful to David Robinson and Raghavendra Rao (Sun), Charles Monia, Joshua Tseng (Nishan), Somesh Gupta (Silverback), Michael Krause, Pierre Labat, Santosh Rao, Matthew Burbridge, Bob Barry, Robert Elliott, Nick Martin (HP), Stephen Bailey (Sandburst), Steve Senum, Ayman Ghanem, Dave Peterson (Cisco), Barry Reinhold (Trebia Networks), Bob Russell (UNH), Eddy Quicksall (iVivity, Inc.), Bill Lynn and Michael Fischer (Adaptec), Vince Cavanna, Pat Thaler (Agilent), Jonathan Stone (Stanford), Luben Tuikov (Splentec), Paul Koning (EqualLogic), Michael Krueger (Windriver), Martins Krikis (Intel), Doug Otis (Sanlight), John Marberg (IBM), Robert Griswold and Bill Moody (Crossroads), Bill Studenmund (Wasabi Systems), Elizabeth Rodriguez (Brocade) and Yaron Klein (Sanrad). The recovery chapter was enhanced with the help of Stephen Bailey (Sandburst), Somesh Gupta (Silverback), and Venkat Rangan (Rhapsody Networks). Eddy Quicksall contributed some examples and began the Definitions section. Michael Fischer and Bob Barry started the Acronyms section. Last, but not least, we thank Ralph Weber for keeping us in line with T10 (SCSI) standardization. We would like to thank Steve Hetzler for his unwavering support and for coming up with such a good name for the protocol, and Micky Rodeh, Jai Menon, Clod Barrera, and Andy Bechtolsheim for helping make this work happen. In addition to this document, we recommend you acquaint yourself with the following in order to get a full understanding of the iSCSI specification: "iSCSI Naming & Discovery"[RFC3721], "Bootstrapping Clients using the iSCSI Protocol" [BOOT], "Securing Block Storage Protocols over IP" [RFC3723] documents, "iSCSI Requirements and Satran, et al. Standards Track [Page 254] RFC 3720 iSCSI April 2004 Design Considerations" [RFC3347] and "SCSI Command Ordering Considerations with iSCSI" [CORD]. The "iSCSI Naming & Discovery" document is authored by: Mark Bakke (Cisco), Jim Hafner, John Hufferd, Kaladhar Voruganti (IBM), and Marjorie Krueger (HP). The "Bootstrapping Clients using the iSCSI Protocol" document is authored by: Prasenjit Sarkar (IBM), Duncan Missimer (HP), and Costa Sapuntzakis (Cisco). The "Securing Block Storage Protocols over IP" document is authored by: Bernard Aboba (Microsoft), Joshua Tseng (Nishan), Jesse Walker (Intel), Venkat Rangan (Rhapsody Networks), and Franco Travostino (Nortel Networks). The "iSCSI Requirements and Design Considerations" document is authored by: Marjorie Krueger, Randy Haagens (HP), Costa Sapuntzakis, and Mark Bakke (Cisco). The "SCSI Command Ordering Considerations with iSCSI" document is authored by: Mallikarjun Chadalapaka, Rob Elliot (HP) We are grateful to all of them for their good work and for helping us correlate this document with the ones they produced. Satran, et al. Standards Track [Page 255] RFC 3720 iSCSI April 2004 Authors' Addresses Julian Satran IBM Research Laboratory in Haifa Haifa University Campus - Mount Carmel Haifa 31905, Israel Phone +972.4.829.6264 EMail: Julian_Satran@il.ibm.com Kalman Meth IBM Research Laboratory in Haifa Haifa University Campus - Mount Carmel Haifa 31905, Israel Phone +972.4.829.6341 EMail: meth@il.ibm.com Costa Sapuntzakis Stanford University 353 Serra Mall Dr #407 Stanford, CA 94305 Phone: +1.650.723.2458 EMail: csapuntz@alum.mit.edu Efri Zeidner XIV Ltd. 1 Azrieli Center, Tel-Aviv 67021, Israel Phone: +972.3.607.4722 EMail: efri@xiv.co.il Mallikarjun Chadalapaka Hewlett-Packard Company 8000 Foothills Blvd. Roseville, CA 95747-5668, USA Phone: +1.916.785.5621 EMail: cbm@rose.hp.com Satran, et al. Standards Track [Page 256] RFC 3720 iSCSI April 2004 Full Copyright Statement Copyright (C) The Internet Society (2004). 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