Oracle Cloud Infrastructure Documentation

iSCSI Commands and Information

Block volumes attached with the iSCSI attachment type use the iSCSI  protocol to connect a volume to an instance. See Volume Attachment Types for more information about volume attachment options.

Once the volume is attached , you need to log on to the instance and use the iscsiadm command-line tool to configure the iSCSI connection. After you configure the volume, you can mount it and use it like a normal hard drive.

To enhance security, Oracle enforces an iSCSI security protocol called CHAP  that provides authentication between the instance and volume.

Note

You do not need to run the iSCSI commands for attachments to volumes configured for the Ultra High Performance level. The Block Volume Management plugin runs the iSCSI commands to configure the iSCSI connection.

For these volumes, you need to ensure that you have configured the required prerequisites and that the Block Volume Management plugin is installed and enabled. For more information, see the following topics:

Accessing a Volume's iSCSI Information

When you successfully attach a volume to an instance, Block Volume provides a list of iSCSI information. You need the following information from the list when you connect  the instance to the volume.

  • IP address
    Note

    When an IP address is assigned to a volume attachment, it is a valid IP address and an iSCSI connection can be made to it. Block Volume does not guarantee the order the IP address is assigned.
  • Port
  • CHAP user name and password (if enabled)
  • IQN
Note

The CHAP credentials are auto-generated by the system and cannot be changed. They are also unique to their assigned volume/instance pair and cannot be used to authenticated another volume/instance pair.

The Console provides this information on the details page of the volume's attached instance. Click the Actions menu (Actions Menu) on your volume's row, and then click iSCSI Information. The system also returns this information when the AttachVolume API operation completes successfully. You can re-run the operation with the same parameter values to review the information.

See Attaching a Block Volume to an Instance and Connecting to a Block Volume for step-by-step instructions.

Recommended iSCSI Initiator Parameters for Linux-based Images

iSCSI attached volumes for Linux-based images are managed by the Linux iSCSI initiator service, iscsid. Oracle Cloud Infrastructure images use iSCSI default settings for the iscsid service's parameters, with the exception of the following parameters:

  • node.startup = automatic
  • node.session.timeo.replacement_timeout = 6000
  • node.conn[0].timeo.noop_out_interval = 0
  • node.conn[0].timeo.noop_out_timeout = 0
  • node.conn[0].iscsi.HeaderDigest = None

If you are using custom images, you should update the iscsid service configuration by modifying the /etc/iscsi/iscsid.conf file.