7.3. Managing target groups¶

7.3.1. Creating target groups¶

Before you create any target groups, assign the network with the iSCSI traffic type to a network interface on each node that you will add to a target group.

To create a target group, you will need a configuration file with a list of nodes to add to the group, as well as target WWNs and portals. For example:

[
  {
    "NodeId": "01baeabee73e4a0d",
    "WWN": "iqn.2013-10.com.vstorage:test1",
    "Portals": [
      {
        "Addr": "192.168.10.11",
        "Port": 3025
      }
    ]
  },
  {
    "NodeId": "0d90158e9d2444e1",
    "WWN": "iqn.2013-10.com.vstorage:test2",
    "Portals": [
      {
        "Addr": "192.168.10.12",
        "Port": 3025
      }
    ]
  },
  {
    "NodeId": "a9eca47661a64031",
    "WWN": "iqn.2013-10.com.vstorage:test3",
    "Portals": [
      {
        "Addr": "192.168.10.13",
        "Port": 3025
      }
    ]
  }
]

In this configuration file:

• NodeId is a node identifier that you can obtain from /etc/vstorage/host_id on a node.
• WWN is a target world wide name:
  • An IQN if iSCSI protocol is used, for example, iqn.2013-10.com.vstorage:test1 (you can only customize the last part after the colon).
  • A WWPN in NAA format if Fibre Channel protocol is used, for example, naa.21000024ff586d3b (you can obtain the port number from /sys/class/fc_host/host6/port_name).
• Portals is one or more target portals, IP address and port combinations that the target will be accessible at. The IP address Addr belongs to a public network interface on the node that handles the iSCSI traffic type. The port Port is optional and defaults to 3260, if omitted.

Once you have the configuration file, for example, tg1.json, you can create the target group with the vstorage-target tg-create command. For example, to create an iSCSI target group, run:

# vstorage-target tg-create -name tg1 -targets tg1.json -type ISCSI
{
  "Id": "3d8364f5-b830-4211-85af-3a19d30ebac4"
}

When you run the command, targets are created on the nodes specified in the configuration file and joined to the target group, target portals are created on the specified network interfaces and ports.

7.3.2. Starting and stopping target groups¶

When you create a target group, its targets are initially stopped. You can start them with the vstorage-target tg-start command. For example:

# vstorage-target tg-start -id 3d8364f5-b830-4211-85af-3a19d30ebac4

This command starts all targets in the group with the ID 3d8364f5-b830-4211-85af-3a19d30ebac4.

All targets in a group can either be running or stopped. So if you add targets to a group of running targets, the new targets will be started automatically.

To stop a target group, use the vstorage-target tg-stop command. For example:

# vstorage-target tg-stop -id 3d8364f5-b830-4211-85af-3a19d30ebac4

This command stops all targets in the group with the ID 3d8364f5-b830-4211-85af-3a19d30ebac4.

7.3.3. Listing target groups¶

You can list target groups with the vstorage-target tg-list command, which displays basic information about groups. For example:

# vstorage-target tg-list
[
  {
    "Id": "3d8364f5-b830-4211-85af-3a19d30ebac4",
    "Name": "tg1",
    "Type": "ISCSI",
    "Running": true,
    "ACL": false,
    "ChapAuth": false,
    "CHAP": {},
    "Mode": 0
  },
  {
    "Id": "78c3b51e-fd9a-485b-91ce-bc0a8171c89d",
    "Name": "tg2",
    "Type": "ISCSI",
    "Running": false,
    "ACL": false,
    "ChapAuth": false,
    "CHAP": {},
    "Mode": 0
  }
]

To print complete information about all target groups, use vstorage-target tg-list -all.

7.3.4. Printing details of target groups¶

To print the details of a specific target group, use the vstorage-target tg-status command. For example:

# vstorage-target tg-status -id faeacacd-eba6-416c-9a7f-b5ba9e372e16

This command prints the complete details of the target group with the ID faeacacd-eba6-416c-9a7f-b5ba9e372e16. One parameter to pay attention to is NodeState. It indicates whether a node is in sync with the target group, that is, aware of its current configuration. The following states can be shown:

• synced: the node is in sync with the target group.
• syncing: the node is syncing with the target group.
• failed: the node failed to sync with the target group (refer to the Error parameter for details).
• offline: the node is offline.
• disabled: the node is disabled and its target is offline.

7.3.5. Managing persistent reservations of target groups¶

SCSI-2 reservations allow initiators to gain exclusive access to a LUN and prevent other initiators from making changes to that LUN at the same time. Such reservations are typically released by the initiator after changes have been made to the LUN. They are, however, also released on initiator failures or logical unit resets. SCSI-3 introduces persistent reservations that remain in case of failures or resets and are released by the initiator when needed. They also allow multiple initiators to communicate with the LUN in a controlled manner.

In Acronis Cyber Infrastructure, persistent reservations are used mostly to support Microsoft Hyper-V nodes working in Failover Clusters.

SCSI persistent reservations are enabled by default. You can enable and disable them, for all volumes in the target group. Do the following:

# vstorage-target tg-pr -id <tg_ID> -enable
# vstorage-target tg-pr -id <tg_ID> -disable

Where <tg_ID> is the ID of the target group for which persistent reservations are set.

7.3.6. Deleting target groups¶

To delete a target group, use the vstorage-target tg-delete command. For example:

# vstorage-target tg-delete -id 3d8364f5-b830-4211-85af-3a19d30ebac4

This command deletes the target group with the ID 3d8364f5-b830-4211-85af-3a19d30ebac4.