iSCSI LUN
An iSCSI LUN (logical unit number) can be mapped to multiple iSCSI Targets to perform storage operations such as read or write. You can create up to 10 or 512 iSCSI LUNs* on a DiskStation.
Note: The number of supported iSCSI LUNs varies on DiskStation/RackStation models. For detailed product specification, please refer to Synology website.
Synology DiskStation provides 3 types of iSCSI LUNs:
Term explanations:
- Thin Provisioning: Thin Provisioning is a method for optimizing storage utilization by allocating storage space in a dynamic and on-demand manner. This setting is only available for iSCSI LUN (regular files).
- VMware VAAI: The VMware vStorage APIs for Array Integration (VAAI) can offload the work of the standard operations on virtual storage arrays to the iSCSI device in the VMware vSphere environment and optimize the storage performance.
- iSCSI Target Mapping: Map the iSCSI LUN to one or more iSCSI Targets.
To create an iSCSI LUN:
- Click Create.
- Select the iSCSI LUN type you want to create.
- Follow the wizard to complete the process.
Note: Advanced LUN features can only be enabled during initial iSCSI LUN creation. This setting cannot be changed afterwards.
To remove an iSCSI LUN:
By removing an iSCSI LUN, all data on the iSCSI LUN will be deleted. The connection between the iSCSI LUN and any mapped iSCSI Target will also be lost.
- Select the iSCSI LUN you'd like to remove.
- Click Remove.
- Click Cancel to abort or OK to confirm.
Note: Deleting VAAI LUNs on the DiskStation does not free up disk space immediately. Data is moved to a system reserved folder called @EP_trash and deleted piece by piece. For example, if a 100 GB VAAI LUN is deleted from the DiskStation, it might take approximately 15-20 minutes to free up the 100 GB of space on the disk volume.
To edit an iSCSI LUN:
- Select the iSCSI LUN you'd like to edit.
- Click Edit.
- Edit the Properties and Mapping to your preference.
- Click OK to save the settings.
Note: To avoid data loss when editing iSCSI LUN capacity, you can only make it larger than the current size.
To take an iSCSI LUN snapshot:
A snapshot of an iSCSI LUN is a point-in-time, read-only copy of an iSCSI LUN.
- Select the iSCSI LUN of which you want to take snapshots.
- Click Snapshot and choose Take a Snapshot.
- Enter the description for this snapshot and click OK.
To restore an iSCSI LUN:
Select a point-in-time snapshot to restore the data on an iSCSI LUN.
- Select the iSCSI LUN you want to restore.
- Click Snapshot and choose Snapshot Manager.
- Select a snapshot to which you want to restore and click Restore.
To clone an iSCSI LUN:
Make a writable copy of an iSCSI LUN or an iSCSI LUN snapshot.
- Select an iSCSI LUN from the left panel or an iSCSI LUN snapshot from Snapshot Manager.
- Click Clone.
- Follow the instructions to complete the process.
Note:
- LUN snapshot/restore and clone functions are only available on iSCSI LUNs with advanced LUN features.
- If you took a snapshot or created a clone, and the status turned out to be Abnormal/Crashed, please delete this snapshot/clone and create another one.
- If there are any connected iSCSI sessions associated with the LUN you are about to clone/restore or take snapshots of, to avoid possible data inconsistency, you must log off from the initiators and stop all related applications before proceeding.
- All changes to a LUN after a snapshot was created will be lost when you restore LUN to this snapshot.
- If the status of an iSCSI LUN changes to Unavailable, it means that some data-related errors occurred while accessing iSCSI LUN. In order to avoid severe data loss on your system, this iSCSI LUN will be temporarily inaccessible. Please contact Synology for support as soon as possible.