A StorageLink SR can provide direct access to high-performance storage, allowing the VMs in your XenServer environment to benefit from array-side enterprise storage services such as replication, de-duplication, thin provisioning, snapshots and cloning, data protection, and performance optimization.
StorageLink SRs use storage adapters to access different storage arrays on all common storage technologies including both NAS and SAN over either Fibre Channel or iSCSI. The features available on a given StorageLink SR depend on the capabilities of the underlying array. StorageLink SRs can co-exist with other SR types on the same storage array hardware, and multiple StorageLink SRs can be defined within the same resource pool.
Depending on your environment and goals, StorageLink provides three advantages:
By default, the XenServer block device-based storage inserts a Logical Volume manager on a disk, either a locally attached device (LVM type SR) or a SAN-attached LUN over either Fibre Channel (LVMoHBA type SR), iSCSI (LVMoISCSI type SR) or SAS (LVMoHBA type SR). When you use StorageLink to configure an SR, LUNs are directly mapped to virtual machines as VDIs. As a result, the array storage abstraction matches the VDI storage abstraction, which is helpful in environments that manage storage provisioning at an array level.
There are two methods of creating StorageLink SRs: allowing StorageLink to create the volume (default) or creating the volume in advance. The default method of creating SRs with StorageLink may not be optimal in all environments.
When StorageLink creates an SR (and the associated LUN and volume), StorageLink automatically creates the initiator group with the Linux operating system. Manually configuring initiator groups with other operating systems is not recommended.
To create a Fibre Channel SR using StorageLink, you should have an iSCSI license on the storage during the initial discovery phase of the NetApp storage controller or be running ONTAP 8.1. If neither one of these apply, create the SR by using the standard SR creation process (without StorageLink) as described in Creating a New SR.