Creating device addresses

The device address determines the access path to a device. A device can have up to eight access paths/device addresses on a Server Unit.

The device addresses must be unique within the configuration.

The device address consists of

• the channel path identifier,

• the 8-byte World-Wide Port Number of the port to which the controller is connected (wwpn operand of the CTL statement),

• the 2-byte Logical Unit Number via which the device is reached by the controller (lun operand of the DVC statement) and

Restrictions

1. A maximum of 256 devices (including the PAV alias devices) may be connected to a logical controller; their Logical Unit Numbers must be identical in the high-order byte. The alias addresses must differ from each other and from the low-order byte of all Logical Unit Numbers of the devices on this controller.

2. If multiple logical controllers are connected to the same port, i.e. with the same World-Wide Port Number, all the devices connected to these controllers must have different Logical Unit Numbers (exception: XPAV, see the “Introduction to System Administration”) [4].
   This can be achieved by devices connected to different logical controllers with the same World-Wide Port Number having a different high-order byte in their Logical Unit Number.
   It is, however, also possible to distribute devices whose Logical Unit Numbers are identical in the high-order byte over several logical controllers with the same World-Wide Port Number. They must then differ in the low-order byte of the Logical Unit Number.

3. In the case of a direct connection (WWPN='0000000000000000'), up to 256 devices can be generated on the channel.

4. Different access paths/device addresses for the same device must differ in the channel path identifier.

Generating a controller with more than 256 devices on one port

The hardware controller is divided into multiple logical controllers each with a maximum of 256 devices. The Logical Unit Numbers of the devices connected to it differ in their high-order byte. The first logical controller thus has ports 0000 - 00FF, the second logical controller ports 0100 - 01FF, and so on. This satisfies the first and second restrictions.

All logical controllers are reached via the same World-Wide Port Number.

 

Example of generating a controller with 2048 devices and 4 ports

The IOGEN statements are, for example:

*
* 4 channels (F0 through F3)
*
CHN F0,IBF,MODE=FCP
CHN F1,IBF,MODE=FCP
CHN F2,IBF,MODE=FCP
CHN F3,IBF,MODE=FCP
*
* 8 logical controllers (C0 through C7) each with 4 channel ports
* via 4 ports with World-Wide Port Numbers (wwpn1 through wwpn4); 
* 256 devices per logical controller
*
CTL C0,,(F0,0,wwpn1),(F1,0,wwpn2),(F2,0,wwpn3),(F3,0,wwpn4)
DVC F000,A5,D,0000,(C0),MULT=256          * Devices F000 ... F0FF *
*
CTL C1,,(F0,0,wwpn1),(F1,0,wwpn2),(F2,0,wwpn3),(F3,0,wwpn4)
DVC F100,A5,D,0100,(C1),MULT=256          * Devices F100 ... F1FF *
*
CTL C2,,(F0,0,wwpn1),(F1,0,wwpn2),(F2,0,wwpn3),(F3,0,wwpn4)
DVC F200,A5,D,0200,(C2),MULT=256          * Devices F200 ... F2FF *
*
CTL C3,,(F0,0,wwpn1),(F1,0,wwpn2),(F2,0,wwpn3),(F3,0,wwpn4)
DVC F300,A5,D,0300,(C3),MULT=256          * Devices F300 ... F3FF *
*
CTL C4,,(F0,0,wwpn1),(F1,0,wwpn2),(F2,0,wwpn3),(F3,0,wwpn4)
DVC F400,A5,D,0400,(C4),MULT=256          * Devices F400 ... F4FF *
*
CTL C5,,(F0,0,wwpn1),(F1,0,wwpn2),(F2,0,wwpn3),(F3,0,wwpn4)
DVC F500,A5,D,0500,(C5),MULT=256          * Devices F500 ... F5FF *
*
CTL C6,,(F0,0,wwpn1),(F1,0,wwpn2),(F2,0,wwpn3),(F3,0,wwpn4)
DVC F600,A5,D,0600,(C6),MULT=256          * Devices F600 ... F6FF *
*
CTL C7,,(F0,0,wwpn1),(F1,0,wwpn2),(F2,0,wwpn3),(F3,0,wwpn4)
DVC F700,A5,D,0700,(C7),MULT=256          * Devices F700 ... F7FF *