DR Design Guides

How to Execute a DR Rehearsal Failover with DR Assistant

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Overview

This option is not a failover , it is a test failover that does not complete all the steps needed to failover users and applications. It does allow testing of write access to production data at a DR location.    It can be used in combination with network and host isolation documented here.

Considerations Before Using DR Rehearsal Mode

  1. Data is not protected on the source cluster while DR Rehearsal mode is enabled.
  2. Eyeglass blocks Uncontrolled Failover Attempt while DR Rehearsal mode is enabled, which means exposure to a real DR event during the DR Rehearsal test.
  3. Mandatory Configuration Change:  The longer you are in active DR Rehearsal and the more data modified during the testing,  the longer it will take to exit DR Rehearsal mode to revert the file system on the DR target to the pre-test state.  This is normal and expected.
    1. It is Mandatory to increase the failover timeout value to 3 hours minimum, to ensure this step does not timeout with the default of 45 minutes.
    2. Login to Eyeglass as admin user over ssh and then run this command:
      1. igls adv failovertimeout set --minutes 180 
  4. Access Zone, IP pool and SyncIQ mode will NOT redirect DNS or SPN and will not require production maintenance window.
  5. WARNING: DFS Mode will redirect users DFS mounts and will require an outage and maintenance window to use this failover mode.


DR Rehearsal Mode Diagram


What Steps Execute During DR Rehearsal Mode Enable

  1. The run SyncIQ step runs to sync data .
  2. DFS Mode :
    1. SMB Shares will be renamed to failover DFS folders during DR Rehearsal for write access testing.
  3. Access Zone, IP Pool, SyncIQ Mode:
    1. No client redirection - SmartConnect names will NOT be redirected to DR cluster.
  4. Allow writes step is completed for policies that are selected.
  5. The source cluster SyncIQ policies are disabled so that will not run while in DR Rehearsal mode.
  6. DR Dashboard will display Active for DR Rehearsal mode.

What Steps Execute During DR Rehearsal Revert

  1. The target cluster will have the disallow writes step execute blocking writes on the target cluster.
  2. DFS Mode:
    1. SMB Shares will be renamed and redirect users connections back to the source cluster.
  3. Access zone, IP Pool, SyncIQ Mode:
    1. No redirection is done, SmartConnect names and spn's were not redirected when entering DR Rehearsal mode.
  4. The source cluster will have the policy enabled.
  5. NOTE: The source cluster policy will not be run and will run on it's previous schedule.
  6. To force sync the source cluster changes to the DR cluster is a manual step by the administrator to run the Source cluster policy, which will cause all changes to the target cluster to be lost.
  7. To monitor progress of disallow writes, login to the DR cluster --> SyncIQ menu --> local targets --> find policy path and verify status is running.   A job report will only appear once this step completes.
  8. done.

How to Enable DR Rehearsal Mode


  1. Configure as per screenshot above and Click Next.
  2. Acknowledge  Support Process has been reviewed.

  3. Review Best practices example below.

  4. Select the Access Zone, IP pool or SyncIQ policies depending on the failover type configured for your environment, then click Next.

  5. Validation Summary Screen is presented and special acknowledgment required for DR Rehearsal Mode that confirms understanding this will stop Data sync between the clusters.  Acknowledge and Click Next.

  6. Final Screen is displayed with final acknowledgment required to Enter DR Rehearsal mode.
  7. Start the DR Rehearsal mode by clicking the start Failover button.

  8. The failover can be monitored with the watch button and use the copy to clipboard option to provide support with the log.
  9. When DR Rehearsal Mode is active a pop up window will appear with a link to next steps.  See example below.

  10. Done


How to Revert DR Rehearsal Mode


  1. Open DR Assistant.
  2. Select the same Source Cluster that was selected when you enabled Rehearsal Mode.
  3. Change Failover Mode to Revert DR Rehearsal mode.

  4. Complete the steps to validate and review acknowledgments.
  5. Start the Revert Failover job.
  6. Review the Failover log with Watch and Copy to Clipboard button.
  7. Once complete source to target cluster policies will be enabled to sync data on the previous schedule.
  8. Done.


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