Amazon EC2 Auto Scaling Introduces Reservations-First Capacity Allocation Strategy

AWS added a new Auto Scaling distribution strategy prioritizing the use of capacity reservations before balancing across Availability Zones to optimize resource utilization.

By Sofia Reed · Editorial pseudonym · 2026-07-03 · 1 min read

AI-ASSISTED REPORTING · RETROSPECTIVE ARCHIVE

Retrospective edition: 2026-07-03. Source published: 2026-06-30. Added to this archive: 2026-11-03. This briefing was prepared later from the linked announcement; it was not published on this website on the historical edition date.

The 'reservations-then-balanced' strategy directs Auto Scaling groups to first place instances into existing On-Demand Capacity Reservations or Capacity Blocks before evenly distributing additional capacity across Availability Zones.

This approach enables customers to maximize the use of pre-purchased capacity resources while maintaining the operational resilience of Auto Scaling. Available across all AWS commercial regions, the feature requires no extra fees beyond standard EC2 charges.

Source & further reading

Amazon EC2 Auto Scaling now supports reservations then balanced Availability Zone distribution ↗

Source published 2026-06-30. This report was prepared with AI assistance from the linked primary-source material. Claims and limitations should be checked against the original announcement or research.