LUN
Before creating a LUN, you need to create a volume first in Storage Manager.
LUN types with different features will be displayed in different colors:
- LUNs with new Advanced LUN features, which support instant snapshots.
- LUNs with Thin Provisioning, including LUNs with legacy Advanced LUN features.
- LUNs without Thin Provisioning; may have better performance in most cases.
Important:
- Only LUNs with new Advanced LUN features support instant snapshots. This type of LUN must be created on Btrfs volumes and are available in DSM 6.2 onwards.
To create a LUN:
- Click Create.
- Set the properties of this LUN.
- LUN name
- Location: You cannot modify the location after a LUN is created, but you can copy this LUN to another volume.
- Capacity: LUN size must be at least 1 GB. For LUNs with legacy Advanced LUN features, the size must be at least 10 GB size.
- Thin Provisioning: You cannot modify Thin Provisioning and space reclamation setting after a LUN is created.
- Advanced LUN features: LUNs with new Advanced LUN features on a Btrfs volume can provide instant snapshots, replication, and cloning.
- Allocation unit size: Only required when using LUNs with legacy Advanced LUN features. Please check the note below to optimize performance.
- Follow the wizard to complete the process.
Note:
- New LUNs cannot be created when a volume has less than 1 GB of free space.
- Advanced LUN features include snapshots, fast clone in the same volume, and storage acceleration commands, such as Microsoft Windows ODX and VMware VAAI.
- Enabling legacy Advanced LUN features may affect the I/O performance.
- The number of supported LUNs varies depending on DiskStation models. For detailed product specifications, please refer to www.synology.com.
Allocation unit size can be optimized for certain application servers such as Microsoft Exchange Server, SQL Server, and virtualization servers, as well as for storage acceleration technologies such as Microsoft Windows ODX or VMware VAAI.
For Standard LUNs with storage acceleration commands enabled, we recommend that you specify the allocation unit size for your application when using the direct connection from your application server or RDM (pass-through) methods. To leverage Synology's storage acceleration technology for Windows ODX, we suggest that you format the NTFS volume with the allocation unit size equal to (or larger than) the one you specified on DSM.
Note:
- Allocation unit size of each volume can be set only once.
To remove a LUN:
When removing a LUN, all data on the LUN will be deleted. Connections between the LUN and any mapped Targets will also be lost.
- Select the LUN you want to remove.
- Click the Remove button and follow the wizard to complete the process.
To edit a LUN:
- Select the LUN you want to edit.
- Click Edit.
- Edit the desired properties.
- Click OK to save the settings.
Note:
- To avoid data loss when editing LUN capacity, you can only make it larger than the current size.
- 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.
If your DiskStation serves as the storage backend of OpenStack Cinder, LUNs with storage acceleration commands will be used when creating Cinder volumes. Operations and management of the LUNs/Targets used by Cinder will be limited on your DiskStation.
- Cinder LUNs cannot be edited.
- Information such as the name, IQN, mapping, and masking of the Cinder Targets cannot be edited.
- You cannot map Cinder LUNs/Targets to general LUNs/Targets.
- You cannot take snapshots of Cinder LUNs via the DSM user interface nor edit, delete or restore snapshots of Cinder LUNs.
- LUNs cloned from Cinder LUNs/snapshots will become general LUNs.
To clone a LUN:
- Select the LUN you want to clone.
- Click Clone.
- Edit the name of the cloned LUN, and select the destination volume.
- Click OK to start cloning.
Additional Information
- You can use the clone feature to move a LUN to another volume.
- With Advanced LUN features, LUNs can be cloned quickly within the same volume.
- LUNs with the new Advanced LUN features can only be cloned to a Btrfs volume.
- When LUNs with legacy Advanced LUN features are cloned to a Btrfs volume, they are converted into LUNs with new Advanced LUN features. When they are cloned to another ext4 volume, legacy Advanced LUN features will be turned off.
- LUN properties will not change after cloning except for LUNs with legacy Advanced LUN features.
- While you are cloning LUNs without Advanced LUN features, it is recommended that you disconnect these LUNs to prevent failed cloning or data inconsistency.
Terminologies:
- Thin Provisioning: Thin Provisioning is a method for optimizing storage utilization by allocating storage space in a dynamic and on-demand manner.
- 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.
- Windows ODX: Offload Data Transfer (ODX) is a new data transfer technology developed by Microsoft in Windows Server 2012 and 8. ODX improves transfer performance by offloading some of the workload to the storage array.
If the data source and destination are located on LUNs that are located on the same volume, cloning will be processed by storage acceleration commands, which saves up to 99.9% of the storage space consumption and accelerates cloning at the same time.
- Target Mapping: Map the LUN to one or more targets.
- Synology Snapshot Manager: Synology Snapshot Manager is a software plug-in, allowing you to take application-consistent snapshots directly from DiskStation Manager (DSM).
- For VMware environment, you will need to install Synology Snapshot Manager on the Windows server where VMware vCenter Server is installed. When a snapshot is triggered on DSM, VMware vCenter Server will be notified and flush all the data from memory to the LUN on which the snapshot is taken to guarantee data consistency. Once the snapshot is complete, VMware vCenter Server will resume normal I/O operation of VMware datastore. Synology Snapshot Manager for VMware vCenter Server supports vSphere 5.1 or newer versions.
- For Windows environment, you will need to install Synology Snapshot Manager on your Windows server. When a snapshot is triggered on DSM, Synology Snapshot Manager will leverage Microsoft Volume Shadow Copy Service (VSS) technology to produce consistent point-in-time copies of data. Synology Snapshot Manager for Windows supports Windows Server 2008 R2, 2012 and 2012 R2.
- Synology Snapshot Manager can be downloaded free from www.synology.com.