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  • (approximate) - DMS tasks stop working

  • 14:10 GMT - Andy finds the the DMS tasks are not running

  • 15:30 GMT - Tasks restarted successfully after the whitelisting of DMS addresses

  • 14:20 GMT - Ticket opened with AWS Support to get information on why the DMS addresses were changed

  • 18:50 GMT - Response from AWS Support

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Root Cause(s)

  • DMS’s address change

    • Why did the DMS address change (& when might it happen again?)

  • Does this mean it’s a firewall thing? MySQL user too? Is there a more dynamic way that we can set this?

    • Use AWS Secrets Manager instead?

  • AWS Support mentioned that a host replacement occurred on both preprod/prod Replication Instances on - AWS Support was unable to get access to the records related to our DMS service issues back in October as the process logs are only kept for a limited time however there is a good chance that a host replacement also occurred in October. The public IPs would have been changed when the hosts were replaced.

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Action Items

Action Items

Owner

Add monitoring to DMS

https://hee-tis.atlassian.net/browse/TIS21-2443

Mitigate to prevent this from happening in the future

https://hee-tis.atlassian.net/browse/TIS21-2515

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Lessons Learned