QNAP Systems Ts 253 User Guide

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and the initiator. The target authenticates the initiator using the first set of username and 
password. The initiator authenticates the target using the Mutual CHAP settings.  
6. Click Next.        
7. Click Finish.        
8. A new target will be created.    
 
Creating iSCSI LUNs 
Follow the steps below to create a LUN for an iSCSI target: 
1. Click Create.        
2. Select iSCSI LUN only and click Next.          
3. Configure the following settings: 
LUN type 
LUN allocation method 
Name 
LUN location 
Capacity 
Alert threshold          
4. Click Next.          
5. Optional: Map the LUN to a target and click Next. 
Important: Selecting Do not map it to a target for now adds the newly created LUN to 
the unmapped iSCSI LUN list. You can add LUNs in this list to the iSCSI Target list at any 
time. 
6. Confirm the settings and click Next.          
7. Click Finish. 
The unmapped LUN is created and listed in the unmapped iSCSI LUN list. 
 
The description of each iSCSI target and LUN status is explained in the table below: 
Item Status Description 
iSCSI target Ready The iSCSI target is ready but no initiator 
has    connected to it yet. 
Connected The iSCSI target has been connected by an 
initiator. 
Disconnected The iSCSI target has been disconnected. 
Offline The iSCSI target has been deactivated and 
cannot be connected by the initiator. 
LUN Enabled The LUN is active for connection and is  
						

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visible to authenticated initiators. 
Disabled The LUN is inactive and is invisible to the 
initiators. 
  
Refer to the table below for actions (the Action button) available to manage iSCSI targets and 
LUNs: 
Action Description 
Deactivate  Deactivate a ready or connected target. Note that the connection from the 
initiators will be removed. 
Activate Activate an offline target. 
Modify Modify the target settings: target alias, CHAP information, and checksum 
settings. 
Modify the LUN settings: LUN allocation, name, disk volume directory, etc. 
Delete Delete an iSCSI target. All the connections will be removed. 
Disable Disable a LUN. All the connections will be removed. 
Enable Enable a LUN. 
Un-map Un-map the LUN from the target. Note that a LUN must first be disabled 
before it can be un-mapped. When clicking this button, the LUN will be 
moved to the un-mapped iSCSI LUN list. 
Map Map the LUN to an iSCSI target. This option is only available on the 
un-mapped iSCSI LUN list. 
View Connections View the connection status of an iSCSI target. 
 
Note: Some of the above options are not available if the iSCSI target is connected. 
 
Switching iSCSI LUNs between targets 
Follow the steps below to switch an iSCSI LUN between targets: 
1. Select an iSCSI LUN to un-map from its iSCSI target.        
2. Click Action > Disable.          
3. Click OK.          
4. Click Action > Un-map to un-map the LUN. The LUN will appear on the un-mapped iSCSI LUN 
list.        
5. Select the un-mapped iSCSI LUN.          
6. Click Action > Map to map the LUN to another target.           
						

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7. Select the target to map the LUN and click Apply.          
8. The LUN will be mapped to the target.  
 
After creating the iSCSI targets and LUN on the NAS, the iSCSI initiator installed on the computer 
(Windows PC, Mac, or Linux) can be used to connect to the iSCSI target and LUN and the disk 
volumes can be used as the virtual drives on the computer. 
  
Expanding iSCSI LUN capacity  
The NAS supports capacity expansion for iSCSI LUNs. To do so, follow the steps below:    
1. Locate an iSCSI LUN on the iSCSI target list.          
2. Click Action > Modify.  
3. Specify the capacity of the LUN. Note that the LUN capacity can be increased several times up to 
the maximum limit but cannot be decreased.          
4. Click Apply to save the settings. 
 
Note: For the type of LUN allocation, the maximum LUN capacity for both thin 
provisioning and instant allocation is 144TB or 250TB if the NAS has more than 4GB RAM.  
 
Optimizing iSCSI Performance 
 
In environments that require high performance storage (virtualization, etc) users are recommended 
optimize the iSCSI and NAS hard disks performance in the following ways: 
Use instant allocation: When creating an iSCSI LUN, select Instant Allocation to achieve 
slightly higher iSCSI performance. However, the benefits of thin provisioning will be lost. 
Create multiple LUNs: Create multiple LUNs according to the number of processors on the NAS 
(this can be found in System Status > Resource Monitor). If the NAS has four processors, it is 
recommended to create four or more LUNs to optimize iSCSI performance. 
Use different LUNs for heavy load applications: Spread applications such as databases and 
virtual machines that need high read/write performance to different LUNs. For example, if there 
are two virtual machines which intensively read and write data on LUNs, it is recommended to 
create two LUNs so that the VM workloads can be efficiently distributed. 
 
Advanced ACL 
 
With the iSCSI advanced access control list (ACL), LUN masking policies can be configured for each 
connected initiator. If the connected initiator is not on the list, the Default policy will be applied to 
that initiator.    
 
Note: This function or its content is only applicable to some models. To check for  
						

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applicable models, please refer to the   product comparison table on the QNAP website. 
 
To use this feature, click Add a Policy. Enter the policy name and the initiator IQN, assign the 
access right for each LUN created on the NAS and click Apply. 
 
For descriptions on each field, refer to the table below:  
Field Description 
Read-only The connected initiator can only read the data from the LUN. 
Read/Write The connected initiator has read and write access rights to the LUN. 
Deny Access The LUN is invisible to the connected initiator. 
 
If no LUN masking policy is specified for a connected iSCSI initiator, the default policy will be applied. 
The system default policy allows read and write access from all the connected iSCSI initiators. Click 
the default policy and Edit to edit the default policy. To delete a policy, select a policy and click 
Delete. 
 
Note: Make sure at least one LUN has been created on the NAS before editing the default 
LUN policy. 
 
Hint: How do I find the initiator IQN? 
Start the Microsoft iSCSI initiator and click General. You can then find the IQN of the 
initiator. 
 
Snapshot 
 
QNAP Snapshot can be used with iSCSI LUNs and volumes in a QNAP NAS to achieve full protection. 
With the QNAP Snapshot Agent, the NAS provides application-consistent snapshots by capturing all 
data in memory and all transactions in process before performing the snapshot. The application will 
then be consistent and include all necessary data. In case of snapshot restoration, no data will be 
missing. 
 
On this page, you can take, manage, or restore application (or crash consistent) snapshots on 
block-based LUNs or check a list of servers with Snapshot Agent installed and set up remote snapshot 
replication jobs. 
 
Note:   
						

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Snapshot Replica (or volumes/LUNs replication between remote servers) is covered in 
Backup Station. For details, please refer to the Snapshot Replica chapter in Backup 
Station.  
Multiple snapshots can only be taken on block-based LUNs, and only one snapshot can 
be taken for file-based LUNs if you use the LUN Backup feature.  
Application consistent snapshots for iSCSI LUN are only available when the Snapshot 
Agent is used and for VMware and VSS-aware applications running on a Windows 
server.  
The function or its content is only applicable on some models. To check for applicable 
models, please refer to the product comparison table on the QNAP website. 
o A minimum of 4 GB RAM is required to use snapshots. 
o x51 series models only support up to 256 snapshots instead of 1024. The HS-251 
does not support snapshots. 
 
Taking a Snapshot 
After reserved space is set, you can take snapshots. To create a snapshot, follow these steps: 
1. Select a LUN from the list and click Snapshot > Take a Snapshot.  
2. Specify the snapshot name and duration to retain the snapshot. 
3. Select between Crash-consistent or application-consistent snapshot types. 
4. Click OK.  
 
Note: Application-consistent snapshots capture all of the data from both volatile (RAM) 
and persistent storage (hard drives). Crash-consistent snapshots only capture the data 
from persistent storage. When restoring an application-consistent snapshot for a VM, all 
of the data (including data stored in volatile storage) will be restored. When restoring a 
crash-consistent snapshot, only data stored in the persistent storage will be restored.  
For Windows-based VMs, the application will need to support VSS and VSS Writer in 
order to take an application-consistent snapshot.  
The options (Application-consistent and Crash-consistent) will only appear after you 
install QNAP Snapshot Agent (this can be downloaded from the QNAP website). If this is 
not installed, all of the snapshots taken will be crash-consistent snapshots. 
 
Managing Snapshots 
You can revert, delete, and clone a snapshot, set up snapshot schedules, or restore snapshot files for 
LUNs or volumes. For more information on these functions, see Managing Snapshots with Snapshot 
Manager for volumes and LUNs.    
 
  
						

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Snapshot Agent 
QNAP Snapshot Agent supports VMware vCenter and Microsoft Volume Shadow Copy Service (VSS). 
Before taking snapshots from the NAS, the Snapshot Agent notifies vCenter or Microsoft Server to 
create VMware snapshots for each virtual machine and store those VMware snapshots to iSCSI LUNs 
(or to flush all the data into the iSCSI LUN,) thereby ensuring application consistent snapshots.  
 
To check connected servers with Snapshot Agent installed, click Snapshot > SnapAgent. On the 
SnapAgent page, you can check the agent IP, agent version, OS, LUN information, and status. Check 
www.qnap.com for details on Snapshot Agent.  
						

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Connecting to iSCSI Targets by Microsoft iSCSI Initiator on Windows 
 
Before you start to use the iSCSI target service, make sure you have created an iSCSI target 
with a LUN on the NAS and installed the correct iSCSI initiator for your OS. 
 
ISCSI initiator on Windows: 
Microsoft iSCSI Software Initiator is an official application for Windows that allow users to 
implement an external iSCSI storage array over the network. 
  
Using iSCSI initiator: 
Start the iSCSI initiator from Control Panel > Administrative Tools. Under the Discovery 
tab click Add Portal (or Discover Portal.) Enter the NAS IP and the port number for the 
iSCSI service. The available iSCSI targets and their status will then be shown under the 
Targets tab. Select the target you want to connect to and click Connect. You can click 
Advanced to specify login information if you have configured the authentication otherwise 
simply click OK to continue. Upon logging in, the status of the target will show Connected. 
 
After the target has been connected Windows will detect its presence and treat it as if a new 
hard disk drive has been added which needs to be initialized and formatted before we can use 
it. Go to Control Panel > Administrative Tools > Computer Management > Disk 
Management and you should be prompted to initialize the newly-found hard drive. Click OK 
then format this drive as you normally would when adding a new disk. After disk initialization 
and formatting, the new drive is attached to your PC. You can now use this iSCSI target as a 
regular disk partition.  
						

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Connecting to iSCSI Targets by Xtend SAN iSCSI Initiator on Mac OS 
 
This section shows you how to use Xtend SAN iSCSI Initiator on Mac OS to add the iSCSI 
target (QNAP NAS) as an extra partition. Before you start to use the iSCSI target service, 
make sure you have created an iSCSI target with a LUN on the NAS and installed the correct 
iSCSI initiator for your OS. 
 
About Xtend SAN iSCSI initiator: 
ATTOs Xtend SAN iSCSI Initiator for Mac OS X allows Mac users to utilize and benefit from 
iSCSI. It is compatible with Mac OS X 10.4.x to 10.6.x. For more information, visit:  
http://www.attotech.com/products/product.php?sku=INIT-MAC0-001 
 
Using Xtend SAN iSCSI initiator: 
Follow the steps below: 
1. After installing the Xtend SAN iSCSI initiator, you can find it in Applications. 
2. Click the Discover Targets tab and choose Discover by DNS/IP or Discover by iSNS 
according to the network topology. In this example, we will use the IP address to 
discover the iSCSI targets. 
3. Follow the instructions and enter the server address, iSCSI target port number (default: 
3260), and CHAP information (if applicable). Click Finish to retrieve the target list. 
4. The available iSCSI targets on the NAS will be shown. Select the target you want to 
connect to and click Add. 
 
You can configure the connection properties of selected iSCSI target in the Setup tab. Click 
the Status tab, select the target to connect to. Then click Login to proceed. The first time 
you login to the iSCSI target, a message will remind you the disk is not initialized. Click 
"Initialize…" to format the disk. You can also open "Disk Utilities" to initialize the disk. You 
can now use the iSCSI target as an external drive on your Mac.  
						

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Connecting to iSCSI Targets by Open-iSCSI Initiator on Ubuntu Linux 
 
This section shows you how to use the Linux Open-iSCSI Initiator on Ubuntu to add the iSCSI target as 
an extra partition. Before you start using the iSCSI target service, make sure you have created an 
iSCSI target with a LUN on the NAS and installed the correct iSCSI initiator for your OS. 
 
About Linux Open-iSCSI Initiator: 
The Linux Open-iSCSI Initiator is a built-in package in Ubuntu 8.04 LTS (and later). You can connect to 
an iSCSI volume at a shell prompt with just a few commands. More information about Ubuntu is 
available at http://www.ubuntu.com and for information and download location of Open-iSCSI, visit: 
http://www.open-iscsi.org 
 
Note: Snapshot LUNs are not supported by the Linux Open-iSCSI Initiator. 
 
Using Linux Open-iSCSI Initiator: 
Install the open-iscsi package. The package is also known as the Linux Open-iSCSI Initiator. 
 # sudo apt-get install open-iscsi 
 
Follow these steps to connect to an iSCSI target with Linux Open-iSCSI Initiator: 
You may need to modify the iscsid.conf for CHAP logon information, such as 
node.session.auth.username & node.session.auth.password. 
 # vi /etc/iscsi/iscsid.conf 
 
Save and close the file, then restart the open-iscsi service. 
 # /etc/init.d/open-iscsi restart 
 
Discover the iSCSI targets on a specific host, for example, 10.8.12.31 with default port 3260. 
 # iscsiadm -m discovery -t sendtargets -p 10.8.12.31:3260 
 
Check the available iSCSI nodes to connect. 
 # iscsiadm -m node 
 
** You can delete the nodes you do not want to connect to when the service is on with the following 
command: 
 # iscsiadm -m node --op delete --targetname THE_TARGET_IQN 
 
Restart open-iscsi to login all the available nodes. 
 # /etc/init.d/open-iscsi restart 
  
						

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You should be able to see the login message as below: 
Login session [iface: default, target: iqn.2004-04.com:NAS:iSCSI.ForUbuntu.B9281B, portal: 
10.8.12.31,3260] [ OK ] 
 
Check the device status with dmesg. 
 # dmesg | tail 
 
Enter the following command to create a partition, /dev/sdb is the device name. 
 # fdisk /dev/sdb 
 
Format the partition. 
 # mkfs.ext3 /dev/sdb1 
 
Mount the file system. 
 # mkdir /mnt/iscsi 
 # mount /dev/sdb1 /mnt/iscsi/ 
 
You can test the I/O speed using the following command. 
 # hdparm -tT /dev/sdb1 
 
Below are some iscsiadm related commands. 
Discover the targets on the host: 
 # iscsiadm -m discovery --type sendtargets --portal HOST_IP 
 
Login a target: 
 # iscsiadm –m node --targetname THE_TARGET_IQN --login 
 
Logout a target: 
 # iscsiadm –m node --targetname THE_TARGET_IQN --logout 
 
Delete a Target: 
 # iscsiadm –m node --op delete --targetname THE_TARGET_IQN