iSCSI Components

iSCSI (Internet Small Computer System Interface) on Linux, including iscsiadm, scsi_id, iscsid, and iscsid.conf.

  1. iscsiadm:

    • Description: iscsiadm is the command-line utility used to manage iSCSI initiators and targets on Linux systems.

    • Functionality:

      • Discovery: Used for discovering iSCSI targets available on the network.

      • Login/Logout: Initiates and terminates sessions with iSCSI targets.

      • Configuration: Allows configuration of iSCSI initiator settings, such as authentication, CHAP (Challenge-Handshake Authentication Protocol), timeouts, etc.

    • Usage:

      • Discovering available iSCSI targets:

        iscsiadm -m discovery -t st -p <target_IP>

      • Logging into an iSCSI target:

        iscsiadm -m node --login

      • Configuring initiator settings:

        iscsiadm -m node --op=update -n node.startup -v automatic

  2. scsi_id:

    • Description: scsi_id is a command-line utility that retrieves unique SCSI (Small Computer System Interface) identifiers from SCSI devices.

    • Functionality:

      • Identification: Provides a unique identifier for each SCSI device, typically based on attributes like vendor, model, serial number, etc.

    • Usage:

      • Retrieve SCSI identifier for a device:

        scsi_id -g -u -s /block/<device>

      • Example:

        scsi_id -g -u -s /block/sda

  3. iscsid:

    • Description: iscsid is the iSCSI initiator daemon that manages iSCSI connections and sessions.

    • Functionality:

      • Daemon: Runs in the background and handles iSCSI connection setup, authentication, and maintenance.

      • Session Management: Monitors and manages iSCSI sessions with targets.

    • Configuration: Controlled via /etc/iscsi/iscsid.conf file.

  4. iscsid.conf:

    • Description: Configuration file for iscsid, containing settings and parameters for the iSCSI initiator daemon.

    • Functionality:

      • Parameters: Configures initiator settings such as discovery mechanisms, authentication methods, timeouts, logging levels, etc.

    • Location: Typically located at /etc/iscsi/iscsid.conf.

Example Use Cases

  • Discovering iSCSI targets:

    iscsiadm -m discovery -t sendtargets -p <target_IP>

  • Logging into an iSCSI target:

    iscsiadm -m node --login

  • Configuring iscsid.conf: Edit /etc/iscsi/iscsid.conf to adjust settings like authentication, session timeouts, and logging levels.

Conclusion

Understanding these tools and configuration files is essential for effectively managing iSCSI storage connections on Linux systems. They facilitate the discovery, connection, and management of iSCSI targets, ensuring reliable and efficient access to remote storage resources. Always refer to the respective man pages (man iscsiadm, man scsi_id, etc.) for detailed usage instructions and additional configuration options available for each tool.

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