Table 30 Restrictions on Remote Command Device

Item

Restriction

 

 

Emulation type

OPEN-V

 

 

Number of LDEVs in an external volume

1

 

 

Cache mode

Disable

 

 

Minimum capacity

96,000 Blocks (about 47 MB)

 

 

Maximum capacity

4 TB

 

 

•The remote command device cannot be identified by the port discovery or volume discovery of XP External Storage.

•When an external storage system (A) has a remote command device (B) [that is, when a command device in another external storage system (C) is mapped to this external storage system (A)], make sure that the remote command device (B) does not have the smallest LUN ID on the port in the external storage system (A).

•You cannot execute I/Os to the remote command device.

•You cannot set the command device disable on the remote command device.

•You cannot set the command device security on the remote command device.

•Do not set the command device security on the external storage system side for the command device that is mapped as a remote command device.

•You cannot create a LUSE volume using a remote command device.

•You cannot create CVs using the VLL function in the remote command device.

•Cache Residency Manager is not available on the remote command device.

Mapping a Command Device as a Remote Command Device

The command devices that can be mapped as remote command devices appear in the Device column of the Volume Operation window as shown in Table 29 (page 121).

To map a command device, select a command device that can be mapped and follow the procedure in “Mapping an External Volume Automatically” (page 67).

Using XP Continuous Access or XP Continuous Access Journal with Remote Command Device

When you want to use XP Continuous Access or XP Continuous Access Journal with a remote command device, you need two different kinds of ports, which are an initiator port for XP Continuous Access or XP Continuous Access Journal and an external port for the remote command device. However, if you set the Initiator/External MIX mode, you will be able to use a port as both initiator port for XP Continuous Access or XP Continuous Access Journal and external port only for the remote command device.

Before you set the Initiator/External MIX mode, you need to prepare initiator ports and external ports in one port block of the Standard mode. You can set the Initiator/External MIX mode on the port block that consists of the initiator ports and external ports.

Figure 42 (page 123) shows the difference between the Standard mode and Initiator/External MIX mode. When the Standard mode is set to the ports, you have to connect the cables for both initiator port and external port. However, if you set the Initiator/External MIX mode, you just need to connect one cable, and you can use XP Continuous Access or XP Continuous Access Journal and remote command device.

122 Remote Command Devices