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Downgrading Data ONTAP using the nondisruptive method

You can downgrade HA pairs within a Data ONTAP release family while maintaining storage system availability. This nondisruptive downgrade method has several steps: initiating a failover operation on one system, updating the "failed" system (and if necessary, its firmware), initiating giveback, and repeating the process on the other system.

Before you begin

Preparatory prerequisites must be satisfied.

Steps

  1. At the console of each storage system, enter the following command to verify that the HA pair is enabled:
    cf status

    If the HA pair is enabled, the cf status command output should be similar to the following:

    Cluster enabled, systemA is up.

    1. If not, enter the following command to enable it:
      cf enable
    2. Verify that the HA pair is re-enabled by entering the cf status command.
  2. Choose one of the following options depending on whether you have already installed new system files:
    If you... Then...
    Have already installed system files At the console of each system, enter the following command to activate the new code on the storage system's boot device:
    download

    The download command provides an acknowledgment similar to the following:

    Tue Jun 19 10:03:22 GMT [download.request:notice]:
    Operator requested download initiated
    download: Downloading boot device
    ......................
    download: Downloading boot device (Service Area)

    Then a message similar to the following appears:

    Tues Jun 19 10:11:51 GMT [download.requestDone:notice]:
    Operator requested download completed
    Note: The storage system console is unavailable until the download procedure is complete.
    Are installing and downloading system files in the same operation At the console of each system, enter the following command:
    software update url|file

    When you use the software update command without the -d option, the download command is executed by default.

  3. If CIFS is in use in System A, terminate it by entering the following command:
    cifs terminate -t nn

    nn is a notification period (in minutes) appropriate for your clients after which CIFS services are terminated. After that period of time, proceed to the next step.

  4. At the console of system B, enter the following command:
    cf takeover

    This command causes system A to shut down gracefully and leaves system B in takeover mode.

  5. Wait 8 minutes to ensure the following conditions:

    • Client multipathing (if deployed) is stabilized.
    • Clients are recovered from the pause in I/O that occurs during takeover.

      The recovery time is client-specific and may take longer than 8 minutes depending on the characteristics of the client applications.

  6. Enter the following command at the console of system B:
    cf giveback

    Attention: The giveback is not initiated and an error message is returned if any conditions such as the following are detected:
    • Open client sessions (such as CIFS sessions)
    • Long-running operations
    • Operations that cannot be restarted (such as tape backup or SyncMirror resynchronization)
    • Error conditions (such as disk connectivity mismatch between the nodes)

    If giveback is not initiated, complete the following steps:

    1. Address the condition described in the error message, ensuring that any identified operations are terminated gracefully.
    2. Enter the cf giveback command with the -f option:
      cf giveback -f

      For more information about the -f option, see the cf(1) man page.

    System A reboots with the new system configuration—a Data ONTAP version or other system firmware and hardware changes—and resumes normal operation as an HA pair partner.

  7. Repeat Step 4 through Step 6 to update the partner storage system.

    System B is brought down and updated while partner A is in takeover mode.