ADR-017: RVTools "MB" Values Treated as MiB (No Conversion)

Status: Accepted Date: 2026-02-19

Context

RVTools column headers use the label "MB" (e.g., "Provisioned MB") but the actual values are base-2 mebibytes, not SI megabytes.

Decision

Read RVTools storage values directly as MiB with no conversion factor applied.

Rationale

• RVTools documentation confirms values are base-2 mebibytes despite the "MB" label
• Cross-checking against LiveOptics exports of the same workloads produces matching totals without conversion
• Applying a 1.048576 (MB-to-MiB) conversion factor would introduce a 4.9% error — a bug, not a fix

Alternatives Considered

• Apply MB-to-MiB conversion: Produces systematically wrong results; a ~5% inflation in required capacity

Consequences

• Column alias dictionaries (ADR-003) map "Provisioned MB" to provisioned_mib with no numeric transformation
• All arithmetic treats the loaded values as MiB throughout the pipeline
• This decision must be revisited if a future RVTools version changes its storage units