Which of the following are the 3 layers of SCSI Target Model? (Multiple Choice)

The SCSI Target Model, as implemented in modern storage systems and covered in the HCIA-Storage curriculum, is a three-layered architecture designed for modularity and flexibility.
1. Port Layer (Frontend): This layer handles the transport-specific protocols, such as iSCSI, Fibre Channel (FC), or FCoE. It is responsible for receiving SCSI commands from the network or fabric and passing them to the middle layer.
2. Middle Layer (Target Core): This is the protocol-agnostic core of the SCSI target. It processes the SCSI commands, manages task sets, and orchestrates the data flow between the port and device layers, independent of the specific transport or backend storage.
3. Device Layer (Backend/Backstore): This layer interacts directly with the underlying storage media. It translates the SCSI commands into operations for the specific backend, which could be a physical disk, a logical volume (LUN), or a file.

A. Network Layer: This term belongs to the OSI model. In the SCSI Target Model, network transport functions are managed by the Port Layer.

1. Huawei Certified ICT Associate - Storage V5.0 Training Material. (HCIA-Storage V5.0). In the module covering storage protocols

the SCSI Target architecture is detailed with its three distinct layers: Port Layer (frontend)

Middle Layer (target core)

and Device Layer (backend). This structure is fundamental to understanding how Huawei storage systems process I/O.

2. University of New Hampshire InterOperability Laboratory (UNH-IOL). Courseware and technical documents on storage protocols

including iSCSI and Fibre Channel

describe the target architecture. The Linux-IO (LIO) Target

a reference implementation

is explicitly structured into these three layers: fabric modules (Port)

the target core (Middle)

and backstores (Device). (Reference: UNH-IOL iSCSI Consortium educational materials).

3. Bovet

D. P.

& Cesati

M. (2005). Understanding the Linux Kernel

3rd Edition. O'Reilly Media. Chapter 14

"The Block Device Layer

" and related sections describe the I/O stack. While not a direct Huawei source

this academic-level text explains the layered model of the Linux I/O subsystem

upon which many modern storage target implementations

including SCSI

are based

showing the separation of transport

core logic

and device driver layers.