Incorrect Recovery Guru message received for Write Back Caching – IBM System Storage

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Source

RETAIN tip: H206651

Symptom

Even though all Logical Unit Numbers (LUNs) are configured with Write Back (WB) cache disabled, the IBM DS Storage Subsystem still receives the following Recovery Guru message:

WB_CACHING_FORCIBLY_DISABLED

This Recovery Guru message did not clear until one of the LUNs was set using the Storage Manager Client Graphical User Interface (GUI) to WB cache enabled and then disabled again.

Affected configurations

The system may be any of the following IBM servers:

  • IBM System Storage DCS3700 Storage Subsystem, type 1818, any model
  • IBM System Storage DS3512, type 1746, any model
  • IBM System Storage DS3524, type 1746, any model
  • IBM System Storage DS3950 Express, type 1814, any model
  • IBM System Storage DS5020 Disk Controller (1814-20A), any model
  • IBM System Storage DS5100 Storage Controller, type 1818, any model
  • IBM System Storage DS5300 Storage Controller, type 1818, any model

This tip is not software specific.

This tip is not option specific.

The 7.77 and 7.83 firmware for the DS3500, DCS3700, DS5020, DS3950, DS5100, and DS5300 is affected.

Solution

This behavior will be corrected in a future release of the 7.8x firmware.

The target date for this release is scheduled for second quarter 2013.

The file is or will be available by selecting the appropriate Product Group, type of System, Product name, Product machine type, and Operating system on IBM Support’s Fix Central web page here

Workaround

To clear the Recovery Guru message, set one of the LUNs using the Storage Manager Client GUI to WB cache enabled and then disabled again.

Additional information

This issue is due to incorrect processing in the controller firmware related to the WB cache Recovery Guru message.

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