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A network share accesses data at the file level (SMB, NFS, or AFP), which is ideal for sharing data among multiple workstations. However, certain working environments require faster transfer rates than file level access can provide. To meet these demands, your NAS OS device supports the creation of iSCSI targets (Internet Small Computer System Interface). As opposed to network shares, iSCSI targets offer enhanced performance by accessing data at the block level. The NAS can also experience lower demand on its CPU when iSCSI is employed since the data is written directly to the volume. Shares that read and write data at the file level require more processing due to IP and networking protocols.
In addition to requiring faster transfer rates, many professional applications are optimized for use with local storage. Potential compatibility issues with standard network volumes include sharing data and network file formats. Therefore, NAS OS iSCSI targets mount on a workstation as local volumes. A workstation that connects to an iSCSI target is called an iSCSI initiator.
The iSCSI initiator must format the NAS's iSCSI target in a non-network file system, such as NTFS, HFS+, or FAT32. For example, an administrator allocates all or a portion of a RAID volume (RAID 1, RAID 5, SimplyRAID, etc.) to an iSCSI target. A workstation on the same network as the NAS becomes an iSCSI initiator. Upon first mounting the iSCSI target, the iSCSI initiator is prompted to format the disk, as would happen with standard local storage (DAS).
An administrator can allocate up to 8TB to an iSCSI target.
The performance offered by an iSCSI target is ideal for applications that use:
It is possible to boost performance even higher by:
For further information on RAID configurations, go to RAID modes. See Network for details on bonding.
In general, a single iSCSI initiator should use an iSCSI target. Once the iSCSI initiator disconnects from the iSCSI target, another initiator on the network can connect to it.
Advanced SAN clusters can be configured to manage multiple iSCSI targets and share them among workstations on the network. When adding a NAS OS iSCSI target to a SAN cluster, the administrator should choose Multiple sessions in the iSCSI target's advanced parameters.
Unless a SAN cluster properly administers it, sharing iSCSI targets can lead to high levels of corrupted data.
Follow the directions below to create an iSCSI target:
The Storage page for the volume provides the iSCSI target status below Associated iSCSI targets:
Choose the Connected to view the IP address of the workstation that has connected to the iSCSI target.
Advanced parameters for an iSCSI target may be changed following its creation.
To review the definitions of the parameters, see Create an iSCSI target.
IQN stands for iSCSI Qualified Name. The IQN field represents the:
The Option window allows you to revise the prefix for the naming authority.
Technical note on changing parameters: It is recommended that the iSCSI initiator disconnects from the iSCSI target before selecting Option. Certain changes to the Advanced parameters may not take effect until the iSCSI target reconnects to the initiator.
A workstation on the network can connect to the NAS's iSCSI target by acting as an iSCSI initiator. While it is not possible to list the directions on how to become an iSCSI initiator for every operating system or third-party application, note the following:
The steps below demonstrate a single connection to an iSCSI target using a Windows 7 workstation as the initiator. For the example, a CHAP has been configured on the iSCSI target only. Configurations will vary but you can review the instructions below and make adjustments for your operating system and network.
The Internet Storage Name Service (iSNS) manages multiple iSCSI targets on a network. Certain iterations of Windows Server include the iSNS feature. Using an iSNS can save time for each iSCSI initiator. For example, rather than searching the network for an iSCSI target, the initiator can look for a connection in a single location, the iSNS server. The iSNS server keeps tabs on all the iSCSI targets on the network, thus allowing the initiator to connect to one that is available.
Configure iSNS on your network server then review the instructions below to add your NAS's iSCSI target.
Enable iSNS server and enter its IP address:
Important info regarding iSCSI volume sharing: Mounting an iSCSI volume on multiple workstations at the same time will lead to serious file corruption. An exception can be found with SAN cluster environments that include servers and software dedicated to managing iSCSI volume sharing. An iSNS server is not considered to be a SAN cluster environment.
The steps below demonstrate a single connection to an iSNS server using a Windows 7 workstation as the initiator. Configurations will vary but you can review the instructions below and make adjustments for your operating system and network.