Storage I/O card modes and jumpers

The 2748 and 2778 I/O cards can run in either compression mode or enhanced mode.

• Compression Mode: Compression mode should only be used when you want to run Integrated Hardware Disk Compression. In compression mode, the write cache size is 4 MB.
• Enhanced Mode: Enhanced mode has an enhanced write cache size. In enhanced mode, the write cache size for the 2748 I/O card is 26MB, and the maximum compressed write cache size for the 2778 I/O card is 104MB. Enhanced mode also provides support for Extended Adaptive Cache (by attachment of a read cache device) and Extended Adaptive Cache Simulator.

The following subtopics are included here:

• Setting or changing the mode of an I/O card.
• When an error regarding the mode of the storage I/O card appears, the error message indicates whether the jumper is missing or overridden.
  • If the error message is CPPEA20, the I/O card has overridden the mode set by the jumper. See Mode jumper has been overridden.
  • If the error message is CPPEA21, the I/O card has detected that the jumper is missing. See Mode jumper is missing.

• Related tasks
• Setting or changing the mode of an I/O card
  Provides detailed steps for setting or changing the mode of an I/O card.
• Mode jumper has been overridden
  Covers how to correct the error message that appears when the mode jumper has been overridden.
• Mode jumper is missing
  The error message CPPEA21 appears when the mode jumper is missing from the storage I/O card.

Setting or changing the mode of an I/O card

How to set or change the mode of an I/O card

The 2748 and 2778 I/O cards support two modes: compression and enhanced. The rear of the I/O card is marked with a C, indicating compression mode, and an E, indicating enhanced mode. Three pins on the rear of the I/O card determine the mode of the card, depending on which of the pins have a jumper placed on them.

The jumper may be moved at any time, but changes only take effect during a system IPL. Refer to the illustration below while changing the mode jumper.

Figure 3. Changing the mode jumper

1. Power off the system, ensuring that no jobs are currently processing (see Powering on and powering off).
2. Choose from the following options:
   • To set the mode of the card to compressed (C), place the jumper on the top and middle pins.
   • To set the mode of the card to enhanced (E), place the jumper on the middle and bottom pins.
3. Select the IPL type and mode.
4. Power on the system.

Mode jumper has been overridden

The error message CPPEA20 appears when the mode jumper has been overridden. This is due to cache data that is in a conflicting mode.

1. To begin correcting this error, examine the mode jumpers in the rear section of the storage I/O card.
   Note:
   The mode jumper is accessible without requiring the removal of the I/O card.
2. Choose from the following options:
   • If the mode jumper is not in the desired position, follow the steps in Setting or changing the mode of an I/O card.
   • If the mode jumper is in the desired position and any other I/O card or device reference codes occurred at about the same time as this error, contact your service representative.
   • If the mode jumper is in the desired position and no other I/O card or device reference codes occurred at about the same time as this error, then power the system down normally and IPL. See Powering on and powering off. This ends the procedure.

Mode jumper is missing

The error message CPPEA21 appears when the mode jumper is missing from the storage I/O card.

1. Locate the jumper.
2. Power off the system. See Powering on and powering off.
3. Install the jumper in the correct position. See Setting or changing the mode of an I/O card.
4. Power on the system. This ends the procedure.