[Increased Error Rate and Latency] Service impact: Increased Error Rate and Latency

We continue to make progress towards resolving the impaired EC2 instances and degraded EBS volumes in a single Availability Zone (use1-az4) in the US-EAST-1 Region. At this time, we wanted to provide some more details on the issue. Beginning on May 7 at 4:20 PM PDT, we began experiencing an increase in instance impairments within the affected zone due to the loss of power during a thermal event. Engineers were automatically engaged within minutes and immediately began investigating multiple mitigations. By 9:12 PM PDT, we restored power to a subset of the affected infrastructure and observed some signs of recovery, which have remained stable. We continue working to bring additional cooling system capacity online, which will enable us to recover the remaining affected hardware in the impacted zone in a controlled and safe manner. Some AWS services, such as IoT Core, ELB, NAT Gateway, and Redshift, continue to see significant improvements in the recovery of their workflows. However, some customers will continue to see their affected EC2 instances and EBS volumes as impaired until we achieve full recovery. If immediate recovery is required, we recommend customers restore from EBS snapshots and/or replace affected resources by launching new replacement resources in one of the unaffected zones. Based on our current mitigation efforts, we expect full recovery to take several hours. We are prioritizing this issue and will provide another update by 6:30 AM PDT or sooner if additional information becomes available.