[Incident Report] There were significant issues on AP-1, but we identified it late as it wasn't by Health Checker.
Resource affected: AP-1 (Tokyo)
When: - 7:20 AM ~ 7:40 AM, June 23 2021 UTC (4:20 PM ~ 4:40 PM, June 23 2021 JST) - 5:20 AM ~ 5:40 AM, June 24 2021 UTC (2:20 PM ~ 2:40 PM, June 24 2021 JST)
Impact: Customers in ap-1 may have experienced chat response delay or failure.
Possible cause: There was an update for the defect of the open channel event, but it caused a heavy load on DB.
Next step: - The issue has been fixed at 14:40 on June 24 KST, and the system backed to normal immediately. - We will follow up on this through postmortem soon if there is any potential risk or not.