60 new EC2 instances in az?

soft limit of 20 EC2 instances per region; increase form and retry the template after your limit has been increased.

Can’t connect

  • Security group port not open

  • no IG on VPN; no route

  • no public IP (EIP or public)

  • no NAT; NAT has packet forwarding disabled

Can’t connect EBS

  • EBS volume in wrong AZ

  • EBS volume in wrong

Can’t create more instances

  • Maxed out # of instances in VPC

AMI unavailable

  • AMIs are region specific; renamed when copied between regions


  • Increase instance size

  • GP to IOPS based storage

Placement group capacity error

  • Stop and start all instances


Load balancing not working between zones

  • Enable Cross-Zone Load Balancing

Instances not being added to ELB

  • Health check to long - could be # of checks or time between checks

  • Configure auto-assign public IP address

Traffic not reaching instances

  • Port mismatch

  • ELB SG is misconfigured

EC2 Access logs show ELB instance IP

  • Config ELB to forward source IP to instance

Auto Scaling

Instances start and stop

  • Scaling policy misconfigured - longer scale down threshold

Modify the Auto Scaling group cool-down timers & modify the Amazon CloudWatch alarm period that triggers your Auto Scaling scale down policy.