Making Changes To Instance Configurations - HP StorageWorks SR2122 User Manual

Maintaining and Managing the Storage Router

Making Changes to Instance Configurations

Note:
cluster, always modify the configuration of a SCSI routing instance from the storage
router where the instance is currently active.
Frequently you will make changes to the SCSI routing instance configurations.
Changes include such actions as adding or deleting a target, adding or deleting a
LUN, remapping a target, or modifying access. It is important to understand the
ramifications of these changes on the IP hosts accessing the associated storage
resources. For example, changing the instance configuration may change the
device presentation to the IP host, effectively changing the name or number
assigned to the device by the host operating system. Certain instance
configuration changes, such as adding or deleting targets, adding or deleting
LUNs within a particular target, or adding or deleting entire instances may change
the order of the devices presented to the host. Even if the host is only associated
with one SCSI routing instance, the device order could make a difference.
Typically, the IP host operating system assigns drive identifications in the order
they are received based on certain criteria. For example, a Linux system assigns
drive identifications in the order they are received based on host, bus, target, and
LUN information. Changing the order of the storage discovery may result in a
changed drive identification. Applications running on the host may require
modification to appropriately access the current drives.
If an entire SCSI routing instance is removed, or there are no targets available for
the host, the host's iSCSI driver configuration file must be updated to remove the
appropriate reference before restarting the iSCSI driver. If a host's iSCSI
configuration file contains a reference to an instance which does not exist or has
no targets available for the host, the iSCSI driver will not complete a login and
will not discover targets associated with any SCSI routing instance.
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To assure that changes are correctly propagated to all storage routers within a
IP Storage Router SR2122-2 User Guide