Expand storage space with the iSCSI target service

iSCSI (Internet Small Computer System Interface) is an IP-based (Internet Protocol) storage network standard for linking data storage installations. By transferring SCSI commands over IP networks, iSCSI is used to simplify location-independent storage and retrieval via LANs (Local Area Networks) and WANs (Wide Area Networks).

iSCSI enables clients such as computers, servers and virtual machines to use storage from your NAS / STORAGE DEVICE as a virtual disk. Clients can partition and format virtual data media just like local data media, and use them as storage for the cloudplan data path.

Definition
iSCSI Target: An iSCSI target storage server
iSCSI initiator: iSCSI initiators connect to the targets and use their storage.
iSCSI LUN: is part of the space that initiators can use by connecting to the target.

Creating an iSCSI target using the example of a QNAP™ NAS
1. Go to Storage & Snapshots> iSCSI Storage.
2. Click New iSCSI Target.
3. Enter a name for the target and an alias, and then click Next.
4. Select Create iSCSI LUN and assign it to this target.
5. Go to Storage & Snapshots> Storage / Snapshot.
6. Select a volume.
7. Choose Create> New File-Based iSCSI LUN.
8. Select a storage pool.
9. Highlight Immediate Assignment and then click Next.
10. Enter the LUN name.
11. Specify the LUN capacity.
12. Assign the LUN to a target and then click Next.
13. Review the overview and then click Finish.

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Connection to an iSCSI target using an iSCSI initiator under Windows™
1. Find the Windows iSCSI initiator and run it.
2. Enter the IP address of the NAS under Targets> Target and click on Quick Connect. The iSCSI initiator searches for available iSCSI targets and adds them to the Detected Targets list.
3. Format the connected LUN as a disk with NTFS Files System in Windows using disk management.
4. Enter a name and a drive letter and save your entries.
5. The iSCSI LUN storage space now appears as a drive in Windows.

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Connect to an iSCSI target using an Open iSCSI initiator on Linux
1. Install the open-iscsi package.

# sudo apt-get install open-iscsi

2. Edit the iscsid.conf file

# sudo nano /etc/iscsi/iscsid.conf

    Change the following entries
        node.startup = automatic
    Optional: Insert the CHAP information for authentication.
        node.session.auth.username=username
        node.session.auth.password=pwd
    Save and close the file.

3. Restart the open-iSCSI service.

# /etc/init.d/open-iscsi restart

4. Detect all iSCSI targets on the iSCSI initiator.
In this example, the NAS IP address is 192.168.10.1 and the default iSCSI port is 3260.

# iscsiadm -m discovery -t sendtargets -p 192.168.10.1:3260

4. Check the available iSCSI nodes.

# iscsiadm -m node

5. Optional: Löschen Sie Knoten, mit denen Sie sich nicht verbinden möchten.

# iscsiadm -m node –op delete –targetname THE_TARGET_IQN

6. Restart the Open iSCSI service for login on all available nodes.

# /etc/init.d/open-iscsi restart

Linux displays a login message.
Example: Login session [iface: default, target: iqn.2004-04.com:TARGET:iSCSI.UbuntuXenial.B9281B, portal: 192.168.10.1,3260] [OK]

7. Check the device status with dmesg.

# dmesg | grep sd

In this example, the device name is /dev/sdb.

8. Create a partition.

# fdisk /dev/sdb

9. Format the partition.

# mkfs.ext3 /dev/sdb1

10. Create a target folder and mount the file system in this folder.

# mkdir /mnt/iscsi
# mount /dev/sdb1 /mnt/iscsi/

The storage target is now ready for use.

11. Finally, add an entry to /etc/fstab to mount the iSCSI drive during startup:

/dev/sdb1       /srv        ext4    defaults,auto,_netdev 0 0

12. Make sure everything works as expected by restarting the server.