Dell EqualLogic PS6210XS EqualLogic Group Manager Administrator s Guide PS Ser - Page 114

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 different computers, from accessing the same target. By default, the group disables multihost (shared) access to a target. Therefore, only one iSCSI qualified name (IQN) can connect to a target at one time. Restriction: If all group members are not running PS Series firmware 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 different 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 qualified 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 different 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. 114 About Volume-Level Security