How to use the iSCSI Target Service on the Synology DiskStation

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Overview

This article aims to illustrate to the administrator on how to use the iSCSI Target of the Synology DiskStation, introduced in DiskStation Manager 2.2. This article was written on DSM 3.0-1354


What is iSCSI?

iSCSI is a protocol to facilitate SCSI-based storage commands to be sent over ubiquitous network structures, such as a LAN or VPN. Using the iSCSI Target Service provides an illusion that a hard drive is locally attached to a computer, and will be managed by a local computer's operating system. In reality, the newly added disk is a virtual drive which exists on the Synology DiskStation. Because the hard drive is virtual, there is no need to add additional hardware to a computer, as the virtual drive is administered through a common network infrastructure.


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How to create an iSCSI Target on the Synology DiskStation

Overview: This article will guide the administrator in the basics of creating an iSCSI LUN on the DiskStation, which can be used with an iSCSI Target for Virtual Storage.


Step 1:

  • Login to the Synology DiskStation Manager as administrator
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Step 2:

  • Launch Storage Manager
  • Click Create
ISCSI-createTrg-dsm30-01.png

Step 3:

  • Select Custom and click next
ISCSI-createTrg-dsm30-02.png

Step 4:

  • Select Regular Files (File-Level) or Block-Level iSCSI LUN
    • File-Level iSCSI allows the creation of targets on existing storage volumes, so that storage may shared between the two storage systems. This guide will cover how to create File-level iSCSI.
    • Block-Level iSCSI allows for faster performance, but requires the usage of an entire storage volume. Using that wizard will involve additional steps to create the target compared to File-based iSCSI, and will be similar to creating a RAID volume on the DiskStation.
    • Further information about File/Block-level iSCSI is available here
ISCSI-createTrg-dsm30-03.png

Step 5:

  • Name: Enter a name for the iSCSI LUN
    • Tip: if using one LUN with one target - please consider using the following format structure to name the iSCSI LUN
    • Format Structure: iqn.yyyy-mm.domain:device.ID
      • Example: iqn.2010-10.Synology-iSCSI:VirtualDisk.01
  • Location: The Location of where the target will reside, if used on a multi-volume DiskStation
  • Thin Provisioning: Available for File-based iSCSI LUNs - this option will allow the iSCSI Target storage capacity to be dynamic and allocated on-demand.
    • Please make sure that the space of the iSCSI Target does not exceed the physical space of the DiskStation. Data loss or communication errors with the iSCSI Target can occur if proper storage management cannot be followed. The administrator of the DiskStation is responsible for managing the data storage capacities of the DiskStation
  • Capacity: Enter the capacity of the iSCSI Target in Gigabytes.
  • iSCSI Target Mapping: Please select Create a new iSCSI Target.
    • Introduced in DSM 3.0 - multiple LUNs can be mapped to a single target - this is used in advanced virtual storage environments, and should be done by experienced administrators only.
  • Click on Next
ISCSI-createTrg-dsm30-04.png

Step 6:

  • Name: Enter a name for the iSCSI Target
    • Tip: if using one LUN with one target - please consider using the following format structure to name the iSCSI LUN
    • Format Structure: iqn.yyyy-mm.domain:device.ID
      • Example: iqn.2010-10.Synology-iSCSI:VirtualDisk.01
  • IQN Enter the IQN name for the iSCSI Target
    • 128 characters maximum, includes letters, numbers, colons, dashes, and periods.
    • Format Structure: iqn.yyyy-mm.domain:device.ID
      • Example: iqn.2010-10.Synology-iSCSI:VirtualDisk.01
  • CHAP is used to authenticate iSCSI Initiators before using the iSCSI Target. Usage of the CHAP Authentication is optional.
    • Select a CHAP Method
      • CHAP will require initiators to be authenticated before accessing the target
      • Mutual CHAP will require both initiators and targets to authenticate each other before facilitating communications.
      • Additional information about CHAP can be found here
    • Name: a user name for the authentication
      • One to twelve characters, using letters or numbers
    • Password: a password for the user name, for authentication
      • 12 to 16 characters, using English letters or numbers
  • Click on Next
ISCSI-createTrg-dsm30-05.png

Step 7:

  • Please confirm final settings and click Apply
ISCSI-createTrg-dsm30-06.png

Step 8:

  • The new iSCSI LUN with a new iSCSI Target has been created.
ISCSI-createTrg-dsm30-07.png

Step 9:

  • Proceed with Further Reading Articles to mount the iSCSI Target on a computer, or use advanced methods of iSCSI.


iSCSI LUN Advanced Options

Overview: This section of the article will cover the advanced options of a File-based iSCSI LUN
Please make sure that an iSCSI LUN has been created that has been mapped to an iSCSI Target before proceeding with the iSCSI LUN Advanced Options.


Step 1:

  • Within the Storage Manager, (please make sure that the Storage Tab has been selected) select an iSCSI LUN and click on Edit and proceed to the Properties Tab
    • Name: The name of the iSCSI LUN
    • Location: The Location of the iSCSI LUN file if using a multiple volumes on the DiskStation
    • Capacity: The Capacity of the iSCSI LUN can be adjusted to a larger capacity.
  • Note: For Block-based iSCSI LUNs - the capacity of the LUN can be adjusted by selecting the LUN and click on Manage and proceed with the Volume Expansion of the Block-based LUN
ISCSI-lunAdvancedOptions-dsm30-01.png

Step 2:

Under the Mapping Tab - the LUN can be associated to many different Targets. Please note that this is an option for experienced administrators for specialized virtual storage environments.

ISCSI-lunAdvancedOptions-dsm30-01.png


iSCSI Target Advanced Options

Overview: This section of the article will cover the advanced options of the iSCSI Target
Please make sure that an iSCSI Target has been created with a mapped LUN before proceeding with the Advanced Options of an iSCSI Target.


Step 1:

  • Within the Storage Manager, select the iSCSI Target tab, select an iSCSI Target and click on Edit
ISCSI-trgAdvancedOptions-dsm30-01.png

Step 2:

  • Under the General Tab, the Name, IQN, and CHAP options can be adjusted
ISCSI-trgAdvancedOptions-dsm30-02.png

Step 3:

  • Under the Advanced Tab, the following options can be adjusted
    • CRC Checksum
      • Enable these options to have the iSCSI Initiator and Target to conduct CRC bit checking - this is typically reserved for those environments that need this level of error resiliency.
    • Allow multiple sessions from one or more iSCSI Initiators
      • Used for iSCSI MPIO or MC/S - to allow multiple sessions or Initiators to communicate with the same target.
        • If used by multiple iSCSI Initiators, using this function requires a cluster-aware file system, such as Vmware Virtual Machine File System, or Oracle Clustering File System. Failure to use a cluster-aware file system will result in data lost or corruption.
      • For further information about using the DiskStation within clustering environments, please look here
  • Segment Bytes
    • Adjusting the sending or receiving segment frame can yield differences in iSCSI performance, best to be used by experienced administrators only.
ISCSI-trgAdvancedOptions-dsm30-03.png

Step 4:

Under the Mapping Tab - the Target can be associated to many different LUNs. Please note that this is an option for experienced administrators for specialized virtual storage environments.

ISCSI-trgAdvancedOptions-dsm30-04.png

Step 5:

  • Under the Masking Tab - the Target can be made accessible or be denied by different iSCSI Initiators, based on the IQN of the iSCSI Initiator.
  • Further Information about Target Masking can be found here
ISCSI-trgAdvancedOptions-dsm30-05.png


Further Reading

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