スポット vs 予約 vs オンデマンド
ワークロードの中断許容度と安定性に応じた料金モデルの選び方。
概要とクイックアンサー
主要プロバイダーは同じコンピュートを3つの料金体系（オンデマンドの弾力性、スポット/プリエンプティブのオークション、予約コミット）で販売します。誤った選択はクラウド請求の典型的な失敗です。
レビュー日
2026-08-22
On-demand: the default you pay a premium for
On-demand is billed per second or hour with zero commitment. It is the right price for spiky, stateful, or hard-to-replicate workloads, and the wrong price for anything that runs 24/7 for months.
Spot: 60-90% off with an eviction notice
Spot instances are excess capacity sold at deep discounts with a short termination warning (30 seconds to 2 minutes depending on provider). They shine for batch jobs, CI runners, rendering, and fault-tolerant worker pools that checkpoint state externally.
Reserved and savings plans: commit to save
One-year and three-year commitments discount steady-state compute substantially on hyperscalers. Commit only after usage has been stable for several months, and prefer convertible terms if your instance mix may change.
A simple decision rule
Runs occasionally or must never be interrupted: on-demand. Interruptible and parallelizable: spot. Runs 24/7 with predictable size: reserved. Re-run this analysis every quarter as workloads change.
要点
- Spot discounts range from 60% to 90% across AWS, Azure, GCP, and Alibaba.
- Reserved commitments reward predictable steady-state workloads.
- Match the pricing model to workload interruptibility, not to habit.
関連するクラウド価格ガイドを見る
別のリージョン、プロバイダー、スペック構成、ワークロード設計を比較します。