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How to fix Virtual Disk Write Policy After Battery Learn Cycle (DCA V2)

Environment

Product Version
DCA V2
Firmware 2A00 or earlier 

Purpose

DCA V2 server runs a scheduled battery learn cycle. The virtual disks transition from WB (write back) to WT (write through) during this process. After the battery learn cycle completes the virtual disks write policy should revert, changing from WT to WB, but it does not revert and it cannot be changed.

Cause

This is a raid controller firmware bug for any firmware prior to 23.22.0-0020

How to determine the raid controller firmware version:  CmdTool264 -AdpAllInfo -aall | grep 'FW Package Build'

Procedure 1

This is the quickest solution to get the customer up and running with optimal performance across the cluster.

Follow the steps to resolve this issue:

  1. Download the latest firmware package for the V2. Currently, it is 2A01 which is found here https://download.emc.com/downloads/DL56289_2A01_Firmware_Update_Utility.tgz
  2. Transfer the firmware package to the mdw on the DCA.
  3. Scp the package to the server experiencing the issue. Example:
     scp dcav2_firmware_2A01.tgz sdw1:/tmp
  4. Make the directoryto put the package contents in and move the tarball to it.
    mkdir /tmp/upgrade  ;  mv /tmp/dcav2_firmware_2A01.tgz /tmp/upgrade/
  5. Untar the package to the temp directory created. Using /tmp/upgrade in this example
    cd /tmp/upgrade/  ;  tar xvfz dcav2_firmware_2A01.tgz
  6. Run a manual firmware upgrade on all raid controller present in the server
    CmdTool264 -AdpFwFlash -f MR59p3.rom -aALL
  7. Reboot is required for the firmware to take effect. Make sure to confirm with the customer that it is ok to do so. Recommended to stop the database for this activity.

Procedure 2

Here is the best solution to ensure this bug does not happen again is to upgrade the firmware on all servers in the DCA.

  1. Download the latest firmware package for the V2. Currently, it is 2A01 which is found here https://download.emc.com/downloads/DL56289_2A01_Firmware_Update_Utility.tgz
  2. Download the firmware update instructions found here: https://support.emc.com/docu56189_DCAv2_Firmware_Update_Utility_Instructions.pdf?language=en_US
  3. Follow the instructions to upgrade firmware on all servers in the DCA. 

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