Guidelines for defining a logical control unit for DS8000

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You can use these guidelines to define a logical control unit (LCU) for a DS8000 storage system.

You need the following information to define the logical control unit:
  • Which devices (arrays) are 3380 format, and which are 3390 format
  • Which devices have PAVs, and which do not
  • How many devices are defined for an LCU
    Notes:
    1. An LCU is equivalent to a logical subsystem (LSS). Like an LSS, an LCU can have a maximum of 256 logical devices or volumes.
    2. Every device has a single unit address (in range 00 - FF).
    3. An LCU can manage a maximum of 256 devices and identifies a device by the unit address.
Update the I/O configuration with the appropriate devices, according to the following guidelines:
  • Three device types are possible for 3380: 3380, 3380B, and 3380A.
  • Three device types are possible for 3390: 3390, 3390B, and 3390A.
  • Any non-PAV 3380 is a 3380, regardless of model.
  • Any non-PAV 3390 is a 3390, regardless of model.
  • Any 3380 PAV base is a 3380B.
  • Any 3390 PAV base is a 3390B.
  • Any alias of a 3380B, regardless of model, is a 3380A.
  • Any alias of a 3390B, regardless of model, is a 3390A.
  • Define only the actual base and alias devices to IOCP or HCD to avoid unnecessary definition of processor subchannels.
  • Define only the unit address range to IOCP or HCD as necessary for the installed devices in an LCU (64, 128, or 256). Defining the unit address range enables you to put more LCUs and devices on a channel path.

Ensure that you document the configuration you define for the DS8000 storage system. Except for the 3380 and 3390 models, the DS8000 configuration and the IOCP input must match.

Note: The CU device is a 2107/242x for any DS8000 device type. In HCD, you can use 3990 as a control-unit type for 3380 and 3390 devices. However, you must use 2107/242x as the control-unit type for 3380B, 3380A, 3390B, and 3390A devices.