HP StorageWorks External Storage XP user guide (T1706-96006, June 2006)

External Storage XP user guide 29
CAUTION: When the Disconnect Subsystem or Disconnect Volume command is executed and all data in
cache memory is written to the external LU, the displayed information for Ex-Dev. Status in the Device list
becomes Disconnect.
Powering external arrays on or off
To power external arrays off
1. Stop read and write I/Os to the external LU that is mapped as a local array internal LDEV and is
located in the external array you want to power off.
2. Execute the Disconnect Subsystem command for the external array you want to power off.
Additional I/O to the external LU is stopped and all data in the local array cache memory is written to
the external LU (all data is destaged). For instructions, see ”Disconnecting external arrays or LUs” on
page 98.
3. Perform other operations required before powering the external array off.
4. Power the external array off.
CAUTION: After executing the Disconnect Subsystem command, if you need to use the mapped external
LU again, execute the Check Paths & Restore Vol. command.
To power external arrays on
1. Power on the external array containing the external LU that is mapped as a local array internal LDEV.
2. Execute the Check Paths & Restore Vol. command. For instructions, see ”Checking the connection
status and resuming external LU operations (Check Paths & Restore Vol.)” on page 100.
CAUTION: When powering the external array off after executing the Disconnect Subsystem command,
you cannot access the mapped external LU from the local array when you initially turn on the external
array. You must execute the Check Paths & Restore Vol. command to resume using the mapped external
LU. The Check Paths & Restore Vol. command checks the defined information and the actual status of the
external LU mapped as a local array internal LDEV. If the external LU is ready to be used as a mapped
volume, the LU is set to accept I/Os and you can resume using the LU as a mapped volume.
Using mapped external LUs from the host connected to the local array
The following sections describe examples of using the mapped external LU from the host connected the
local array.
Writing new data to mapped external LUs
Figure 9 shows an example of writing new data in the mapped external LU from the host connected to the
local array.
1. Use the External Storage XP GUI to map the LU in the external array as an internal LDEV of the local
array.
CAUTION: You must set IO Suppression mode to Disable.
You can select the mapped volume’s emulation type as required. If you select an emulation type for an
open-system (such as OPEN-V), go to step 2. If you select an emulation type for a mainframe system
(such as 3390-3), go to step 3.
For more information, see ”Mapping external LUs (Add LU)” on page 73.
2. For open-system emulation types (such as OPEN-V, which HP recommends), the status of the mapped
LDEV is set to Normal and is not automatically formatted. To optimally initialize the mapped LU’s data