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ADR-042: Web Servers Default to Content Included (DRR=5)

Status: Accepted Date: 2026-02-19

Context

The DRR reference table distinguishes two web server subcategories: "content included" (DRR=5) and "content not included" (DRR=1.5). VM naming does not reliably indicate which subcategory applies.

Decision

VMs classified as web servers default to the "content included" subcategory (DRR=5).

Rationale

  • DRR=5 is the middle ground between best-case and worst-case for web workloads
  • "Content included" (static assets, media files) is a common web server configuration in enterprise environments
  • DRR=1.5 for "content not included" (pure reverse proxy, load balancer) would be pessimistic for most real-world web servers
  • Users can override to DRR=1.5 for servers they know are content-free

Alternatives Considered

  • Default to content not included (DRR=1.5): More conservative but likely to understate the actual reduction ratio for most web servers; requires more user overrides

Consequences

  • Sizing reports may be optimistic for environments with many pure-proxy web servers that users do not override
  • The review step is important for accurate results; pre-sales engineers should be trained to ask customers about web server content types
  • Consistent with the project's general philosophy: show a reasonable default, require explicit user action to change to a more conservative estimate