How to create an iSCSI target LUN on your QNAP NAS

What is iSCSI and how can you benefit from it?
iSCSI, (Internet Small Computer System Interface), an Internet Protocol (IP)-based storage networking standard for linking data storage facilities. By carrying SCSI commands over IP networks, iSCSI is used to facilitate data transfers over intranets and to manage storage over long distances. iSCSI can be used to transmit data over local area networks (LANs), wide area networks (WANs), or the Internet and can enable location-independent data storage and retrieval. (Quoted from Wikipedia.)

An all-in-one storage solution with high ability of expansion and low establishment cost is often sought by most SMB storage infrastructure planners who have budget concerns and overall ease of deployment. With the iSCSI service on QNAP Turbo NAS, it can instantly be served as your storage expansion or backup destination of the application servers, such as database server, mail server, or Time Machine (for Mac OS X 10.5 or later) in the business environment. This article demonstrates how you can use the iSCSI target service on QNAP NAS for storage expansion on different operating systems. See below for the usage scenario.

Things to know before we start
In between the relationship of your computer and the storage device, your computer is called an 'initiator' because it initiates the connection to the device, which is called a 'target'.

Note: It is NOT suggested to connect to the same iSCSI target with two different clients (iSCSI initiators) at the same time, unless you are using clustering technologies. Otherwise, this may lead to data crash or disk damage.

To begin, simply follow the step-by-step guide below.

Create an iSCSI target volume
Login your QNAP NAS as an administrator. Go to 'Disk Management' > 'iSCSI' > 'TARGET MANAGEMENT' > 'Create New iSCSI Target' to create a new iSCSI target.

If it is the first time you go to that panel, you will be prompted to use the configuration wizard (If not, you can click "Quick Configuration Wizard").

Just click "OK".

Select on of the following options:

• Create an iSCSI Target with a mapped LUN
• Create only the Target
• Create only the LUN.

In our case, we choose to create "iSCSI Target with a mapped LUN". Click "NEXT".

Click "NEXT" again.

Enter the target name and its alias:

Target Name: This will be a part of your iSCSI target name.

Target Alias: This will be an alias that you can choose to easily identify the target.

Once done, click "NEXT"

The next window allows you to set up password authentication to the target you are creating. You are free to activate the authentication and set up a user name and a password (please refer to the manual). In our example, we will not use authentication. Click "NEXT".

On the next windows we will define your LUN properties:

• LUN Allocation:
  Thin provisioning: The space is allocated only when needed. Advantages of Thin Provisioning on QNAP NAS: With thin provisioning, you can flexibly allocate the disk space (on iSCSI LUN) to the server applications to expand the storage capacity anytime regardless of their current storage size. The adding of the storage space on the servers can be easily done on different operation systems by the iSCSI initiator. Thin provisioning allows efficient storage management since the system administrator has to monitor only the storage capacity of one single server (QNAP NAS) rather than extra hard drives or tapes on other sub-storage systems. Over-allocation is allowed since the storage capacity of the NAS can be expanded by Online RAID Capacity Expansion
  Instant Allocation: The space will be allocated now. If you create a 50 GB LUN, then 50 GB will be immediately reserved for that LUN. (Note that the creation will also take more time because of that process).
• LUN Name: The name that you want to give to your LUN.
• LUN Location: The location where you want to create the LUN. You can choose any volume present on your NAS. For each one you will see the available free space.

Let's use "Thin provisioning" and create a LUN named "MyLunName" with 1 GB capacity. Then click "NEXT".

You will see a summary of your configuration choices:

Click "NEXT". The target and the LUN will be created. You will see the last window showing the success of the operation.

You will see your new target on the "TARGET MANAGEMENT" page.

You can click the "+" icon in front of the target alias to develop your target information.

You will be able to see all the components we created before with your settings:

You can find:

• The target.
• The LUN.
• The 3 names you have chosen: mytargetname, MyEasyAliasName and MyLunName.
• The status of each target and LUN.

Now that your target is "Ready" and your LUN is "Enabled", you can connect to it from an iSCSI initiator installed on your operating system.

For more details about using advanced functionalities like ACL, map or unmap a LUN, please refer to the manual.