External Storage XP user guide 27
Figure 8 Alternate path mode is Single mode with alternate paths in Standby only
NOTE: External disk arrays with Active/Standby (A/S) controllers, such as the MSA, are an
example of Figure 8. A notable characteristic of using A/S controller disk arrays as external storage
is that there is typically only a single port to the owning controller. Paths to the non-owning external
controller’s ports are shown as Standby status. I/O load balancing does not occur across external
controllers.
Turning a disk array’s power on or off
This section describes procedures for turning the power on or off at the local disk array and external disk
array after External Storage XP operations have begun.
These procedures use the following commands:
• Disconnect Subsystem
Execute the Disconnect Subsystem command from the Command View XP or XP Remote Web Console
GUI when you need to perform maintenance or stop the local disk array or external disk array. This
command cancels acceptance of all host I/O operations to the external LU mapped as the internal XP
LDEV. All outstanding data in cache memory on the local disk array intended for the external LU is
written (de-staged) to the external LU.
For instructions on executing the Disconnect Subsystem command, see ”Disconnecting external disk
arrays or external LUs” on page 85.
NOTE: To disconnect an individual LU, use the Disconnect Volume command. To delete a single
external LU’s mapping, use the Disconnect Volume command and then the Delete LU command. For
instructions, see ”Deleting external LU mappings (Delete LU)” on page 92.
• Check Paths & Restore Vol.
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