8.11 Adding Disks Used for Mirroring among Servers

When adding disks used for mirroring among servers, configure iSCSI device according to this procedure.

When adding disks to both nodes, after performing this procedure on a node, perform the same procedure on the other node.

Add disks.
On the node where the disks are added, modify the target settings to add the information of the added disks.
2-1. Execute targetcli to enter the interactive mode.
```
# targetcli
```
2-2. Register a disk or a partition of a local node where the mirroring among servers is performed.
```
/> /backstores/block/ create storage_name device_path
```
Point
- Specify any character string for storage_name.
- For device_path, specify the path for the by-id file of a disk or a partition on a local node which is used for the mirroring among servers.
  In an Azure environment, a NIFCLOUD environment, or an environment where the by-id file does not exist, do not specify the path for the by-id file, but create a partition in the disk where the gpt disk label is set, and specify the path for the by-partuuid file for that partition.
Execution example
```
/> /backstores/block/ create storage1 /dev/disk/by-id/scsi-3500000e111c56611
```
2-3. Confirm iqn name.
```
/> /iscsi/ ls
```
Execution example
```
  /> /iscsi/ ls
  o- iscsi ..................................................................... [Targets: 1]
    o- iqn.2003-01.org.linux-iscsi.node1.x8664:sn.2613f8620d98 .................... [TPGs: 1]
      o- tpg1 ........................................................ [no-gen-acls, no-auth]
        o- acls ................................................................... [ACLs: 0]
        o- luns ................................................................... [LUNs: 0]
        o- portals ............................................................. [Portals: 0]
```
This example shows that iqn name is "iqn.2003-01.org.linux-iscsi.node1.x8664:sn.2613f8620d98".
2-4. Connect the device registered in step 2-2.
```
/> /iscsi/iqn_name/tpgX/luns create /backstores/block/storage_name
```
Point
- Specify the iqn name confirmed in step 2-3 to iqn_name.
- Specify the directory name (such as tpg1) created in iqn_name directory to tpgX.
- Specify the storage name registered in step 2-2 to storage_name.
Execution example
```
/> /iscsi/iqn.2003-01.org.linux-iscsi.node1.x8664:sn.2613f8620d98/tpg1/luns create \
/backstores/block/storage1
```
2-5. End the interactive mode of targetcli. This operation records the settings.
```
/> exit
```
Execute the following on both nodes to rescan iSCSI session.
```
# iscsiadm -m session --rescan
```

Confirm that LUN was added on both nodes.

# iscsiadm -m session -P 3

Execution example

  # iscsiadm -m session -P 3
  iSCSI Transport Class version xxxxxxxx
  version xxxxxxxx
  Target: iqn.2003-01.org.linux-iscsi.node2.x8664:sn.c585c8864f22
      Current Portal: 192.168.56.10:3260,1
      Persistent Portal: 192.168.56.10:3260,1
          **********
          Interface:
          **********
  ...
          iSCSI Connection State: LOGGED IN
          iSCSI Session State: LOGGED_IN
          Internal iscsid Session State: NO CHANGE
  ...
          ************************
          Attached SCSI devices:
          ************************
          Host Number: 12 State: running
          scsi12 Channel 00 Id 0 Lun: 0
              Attached scsi disk sdd State: running
  ...
  Target: iqn.2003-01.org.linux-iscsi.node1.x8664:sn.2613f8620d98  (*1)
      Current Portal: 192.168.56.20:3260,1
      Persistent Portal: 192.168.56.20:3260,1
          **********
          Interface:
          **********
  ...
          iSCSI Connection State: LOGGED IN
          iSCSI Session State: LOGGED_IN
          Internal iscsid Session State: NO CHANGE
  ...
          ************************
          Attached SCSI devices:
          ************************
          Host Number: 13 State: running
          scsi13 Channel 00 Id 0 Lun: 0
  ...
          scsi13 Channel 00 Id 0 Lun: 2                        (*2)
              Attached scsi disk sde State: running            (*3)
  ...

This example shows that sde (*3) for LUN2 of (*2) was added in the target "iqn.2003-01.org.linux-iscsi.node1.x8664:sn.2613f8620d98" of (*1).