iSCSI Initiator for Linux


  • Package iscsi-initiator-utils

  • Package device-mapper-multipath


Install the iSCSI initiator and multipath tools:

yum install iscsi-initiator-utils
yum install device-mapper-multipath


  1. Create the default /etc/multipath.conf file and enable the multipathd service:

    mpathconf --enable --with_multipathd y
  2. Add the following to the /etc/multipath.conf file:

    devices {
            device {
                    vendor                 "LIO-ORG"
                    product                "TCMU device"
                    hardware_handler       "1 alua"
                    path_grouping_policy   "failover"
                    path_selector          "queue-length 0"
                    failback               60
                    path_checker           tur
                    prio                   alua
                    prio_args              exclusive_pref_bit
                    fast_io_fail_tmo       25
                    no_path_retry          queue
  3. Restart the multipathd service:

    systemctl reload multipathd

iSCSI Discovery and Setup:

  1. Enable CHAP authentication and provide the initiator CHAP username and password by uncommenting and setting the following options in the /etc/iscsi/iscsid.conf file:

    node.session.auth.authmethod = CHAP
    node.session.auth.username = myusername
    node.session.auth.password = mypassword

    If you intend to use mutual (bidirectional) authentication, provide the target CHAP username and password:

    node.session.auth.username_in = mytgtusername
    node.session.auth.password_in = mytgtpassword
  2. Discover the target portals:

    iscsiadm -m discovery -t st -p,1,2
  3. Log in to the target:

    iscsiadm -m node -T -l

Multipath IO Setup:

  1. The multipath daemon (multipathd) uses the multipath.conf settings to set up devices automatically. Running the multipath command shows that the devices have been set up in a failover configuration. Notice that each path has been placed into its own priority group:

    multipath -ll
    mpathbt (360014059ca317516a69465c883a29603) dm-1 LIO-ORG ,IBLOCK
    size=1.0G features='0' hwhandler='1 alua' wp=rw
    |-+- policy='queue-length 0' prio=50 status=active
    | `- 28:0:0:1 sde  8:64  active ready running
    `-+- policy='queue-length 0' prio=10 status=enabled
      `- 29:0:0:1 sdc  8:32  active ready running

    You should now be able to use the RBD image in the same way that you would use a normal multipath iSCSI disk.

  2. Log out of the target:

    iscsiadm -m node -T -u