Administrator Guide

About Multihost Access to Targets
In a shared storage environment, you must control computer access to iSCSI targets (volumes and snapshots), because multiple
computers writing to a target in an uncoordinated manner will result in volume corruption.
When an initiator tries to log in to a target, the group uses access control policies to determine if access should be authorized.
However, access control policies do not prevent multiple initiators, either on the same computer or dierent computers, from
accessing the same target. By default, the group disables multihost (shared) access to a target. Therefore, only one iSCSI qualied
name (IQN) can connect to a target at one time.
Restriction: If all group members are not running PS Series rmware version 5.0 or later, the group allows multihost
access to targets.
If you disable multihost access to a volume, when an initiator tries to log in to the volume:
• If an iSCSI initiator is not connected to the volume, the group uses access control policies to determine whether to authorize
access.
• If an initiator is connected to the volume, the group compares the IQN of the current connection to the IQN of the incoming
connection. If the IQNs are not the same, access is denied. If the IQNs are the same, the group uses access control policies to
determine whether to authorize access.
However, some environments might need multihost access to a target. You can enable multihost access to a target if you meet one
of the following conditions:
• Your cluster environment gives the initiators on each cluster computer a dierent IQN, and the environment can manage multiple
connections to a target. For example, the environment uses a Distributed Lock Manager or SCSI reservations.
• Your multipathing solution does not use the same IQN on all initiators, and you cannot modify the names to be the same.
• You use an environment, such as a virtual server, that can manage multiple connections to the same iSCSI target (for example,
through SCSI reservations).
• Initiators on a single computer do not use the same IQN.
In all cases, use access control policies as the primary method of protecting iSCSI targets in a group.
You can enable or disable multihost access when creating a volume. You can also modify a volume or snapshot and enable or disable
multihost access.
Allow or Disallow Multihost Volume Access
In a shared storage environment, you must control computer access to iSCSI targets (volumes and snapshots), because multiple
computers writing to a target in an uncoordinated manner will result in volume corruption.
You can allow or disallow multihost (shared) access to a volume. If you disallow multihost access to a volume, only one iSCSI qualied
name (IQN) can connect to the volume at one time. However, if you have a certain environment, you might want to allow multihost
access to a volume.
NOTE: Before disallowing multihost access to a volume, disconnect all initiators from the volume except one, unless the
initiators have the same IQN. If multiple initiators with dierent IQNs have connections to the volume, you cannot
disallow multihost access.
To allow or disallow multihost access to a volume:
1. Click Volumes.
2. Expand Volumes and then select the volume name.
3. Click Set access type to open the Set Access Type dialog box.
4. Choose to allow or disallow multihost access.
5. Click OK.
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About Volume-Level Security