[스토리지] iSCSI (RFC 3720)

* 출처 - https://tools.ietf.org/html/rfc3720

1. Introduction

iSCSI (Internet Small Computer Systems Interface) 는 SCSI 패킷을 TCP/IP로 감싸 SCSI 장비를 네트워크로 관리할 수 있게 해주는 프로토콜이다.

iSCSI/SCISI 서버를 타겟 (Target), 클라이이언트를 이니시에이터 (Initiator) 라고 부른다.

2. Definitions and Acronyms

(1) Alias : 사용자 편의를 위한 iSCSI 이름 (문자열)

(2) CID (Connection ID) : 타겟과 이니시에이터 사이의 연결 (세션)의 ID. (고유값)

(3) Connection : 타겟과 이니시에이터 사이의 TCP 연결. 컨트롤 메시지, SCSI 커맨드, 파라미터, 데이터를 전달.

3. iSCSI Name Type

(1) iqn (iSCSI Qualified Name)

iSCSI 도메인 네임.

"iqn." 으로 시작

date code는 yyyy-mm 포맷.

4. iSCSI & SCSI Architecture model

4.1. SCSI to iSCSI Concepts Mapping Model

4.2. SCSI Architecture Model

5. Login Phase

5.1. Login Phase Start

-Protocol version supported by the initiator.

-iSCSI Initiator Name and iSCSI Target Name

-ISID, TSIH, and connection Ids

-Negotiation stage that the initiator is ready to enter.

6. Error Handling and Recovery

7. Standard Connection State Diagrams

7.1. State Descriptions for Initiators and Targets

(1) S1 : FREE - instantiation or connection closure 성공 후

(2) S2 : XPT_WAIT - 커넥션 생성 요청 이후 대기상태 (only for Initiator)

(3) S3 : XPT_UP - 로그인 프로세스 대기상태 (only for Target)

(4) S4: IN_LOGIN

- initiator: Waiting for the Login process to conclude, possiblyinvolving several PDU exchanges.

- target: Waiting for the Login process to conclude, possibly involving several PDU exchanges.

(5) S5: LOGGED_IN

- initiator: In Full Feature Phase, waiting for all internal, iSCSI, and transport events.

- target: In Full Feature Phase, waiting for all internal, iSCSI, and transport events.

(6) S6: IN_LOGOUT

- initiator: Waiting for a Logout response.

- target: Waiting for an internal event signaling completion of logout processing.

(7) S7: LOGOUT_REQUESTED

- initiator: Waiting for an internal event signaling readiness to proceed with Logout.

- target: Waiting for the Logout process to start after having requested a Logout via an Async Message.

(8) S8: CLEANUP_WAIT

- initiator : Waiting for the context and/or resources to initiate the cleanup processing for this CSM.

- target : Waiting for the cleanup process to start for this CSM.