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Sharing Virtual Disks via iSCSI

Virtual disks can be shared using the iSCSI protocol. iSCSI is used to facilitate data transfers over intranets and manage storage over long distances. The protocol requires describing the hosts allowed to connect (called remote initiators), the endpoints on the appliance (called local targets) and a LUN (logical unit number) associated to the virtual disk for that connection.

iSCSI sharing concepts

iSCSI is composed of two major components: an iSCSI remote initiator (client initiating a connection) and an iSCSI local target (a storage resource located on a server, made available to clients). At the moment, Syneto Storage can only be configured as a target (other initiators will access its shared data).

Remote initiators and local targets are identified by strings using an iqn, wwn or eui format. See the RFC 3720 for details.

Remote initiators must be part of a  remote initiator group. Local targets can be part of a local target group, but it’s not mandatory. Initiator groups are used for sharing virtual disks to multiple initiators at the same time. Target groups are used to share a virtual disk via multiple targets at the same time.

Note: A target or an initiator cannot be part of multiple groups at the same time.

The image below presents an overview on the iSCSI sharing mechanism:

Sharing virtual disks using the Syneto Storage

These are the steps required to make a virtual disk available to one or more iSCSI initiators:

  1. Enable iSCSI sharing

  2. Click New initiator and enter its identifier and the group it will belong to (you can also create a new group at this step). Groups are collections of iSCSI initiators.
    Click Add and the new initiator will be added.

  3. If desired, create a local target and associate it to a group (click New target, enter its identifier and group, then click Add). However, creating a local target is not required, as a default local target is created when the machine is installed.

  4. Go to the page Data Management -> Folders / Virtual Disks and select the virtual disk you want to make available to the newly created remote initiator group. If you don’t have a virtual disk to share, first create one (see how on Folders and Virtual Disks).

  5. Select the iSCSI/FC share tab.

  6. Click on the new iSCSI share button (+), select the initiator group from step 6, the target group from step 4 (if you defined one; if not, make it available through all targets by leaving All selected) and choose a logical unit number (LUN). Click Add.

    Note: the LUN number must be unique for the selected initiator group (i.e. one remote initiator group can view only one virtual disk on the same LUN)

  7. At this point the hosts from the remote initiator group can access the virtual disk.

Configuring iSCSI initiators on different platforms