Over two years I think we'd see about 2-3 AZ issues but only once I would consider it an outage.
Usually there would be high network error rates which were usually enough to make RDS Postgres fail over if it was in the impacted AZ
The only real "outage" was DNS having extremely high error rates in a single us-east-1 AZ to the point most things there were barely working
Lack of instance capacity, especially spot, especially for the NVMe types was common of CI (it used ASGs for builder nodes). It'd be pretty common for a single AZ to run out of spot instance types--especially the NVMe ([a-z]#d types)
Usually there would be high network error rates which were usually enough to make RDS Postgres fail over if it was in the impacted AZ
The only real "outage" was DNS having extremely high error rates in a single us-east-1 AZ to the point most things there were barely working
Lack of instance capacity, especially spot, especially for the NVMe types was common of CI (it used ASGs for builder nodes). It'd be pretty common for a single AZ to run out of spot instance types--especially the NVMe ([a-z]#d types)