3-2-4 iSCSI (Internet Small Computer System Interface) Explained

Key Concepts

• iSCSI Protocol
• iSCSI Initiator
• iSCSI Target
• iSCSI Sessions
• iSCSI Use Cases

iSCSI Protocol

iSCSI (Internet Small Computer System Interface) is a storage networking standard that allows block-level storage to be accessed over an IP network. It enables the use of existing Ethernet infrastructure for SAN (Storage Area Network) connectivity, reducing the need for specialized Fibre Channel hardware.

iSCSI Initiator

The iSCSI Initiator is a software or hardware component that initiates requests to an iSCSI Target. It resides on the server or client machine and is responsible for sending SCSI commands over the network to the iSCSI Target. The Initiator establishes and manages the connection to the storage device.

iSCSI Target

The iSCSI Target is the storage device or array that responds to requests from the iSCSI Initiator. It receives SCSI commands over the network and performs the corresponding actions on the storage media. The Target can be a physical storage device or a virtual storage resource.

iSCSI Sessions

An iSCSI Session is a connection between an iSCSI Initiator and an iSCSI Target. Multiple sessions can be established between the same Initiator and Target to improve performance and redundancy. Each session can handle multiple I/O operations simultaneously, enhancing the efficiency of data transfer.

iSCSI Use Cases

iSCSI is used in various scenarios, including:

• Remote Storage Access: iSCSI allows servers in different locations to access centralized storage over the network, enabling remote data access and management.
• Virtualization: iSCSI is commonly used in virtualized environments to provide shared storage for virtual machines, improving resource utilization and flexibility.
• Disaster Recovery: iSCSI can be used to replicate data to remote locations, ensuring data availability and recovery in case of a disaster.

Examples and Analogies

Think of iSCSI as a courier service that delivers packages (data) between different locations (servers and storage devices). The iSCSI Initiator is like the sender who prepares and sends the package, while the iSCSI Target is like the receiver who processes and stores the package. Multiple couriers (sessions) can be used to deliver packages simultaneously, ensuring fast and reliable delivery.

Another analogy is a shared kitchen in a dormitory. The iSCSI Initiator is like a resident who requests ingredients (data) from the kitchen (storage device), and the iSCSI Target is like the kitchen staff who prepares and provides the requested ingredients. Multiple residents (sessions) can request ingredients at the same time, ensuring efficient and smooth operation.