By obtaining virtual machines (VMs) from infrastructure providers (InPs) according to the demand in public cloud services, service providers (SPs) can elastically provide network services to users. As the charging methods of VMs, reserved instance (RI) and on-demand instance (ODI) are widely used. For InPs, RI is more desirable than ODI thanks to easiness of estimating long-term revenue, risk aversion of occurring idle VM resources, and reduction of charging cost. In this paper, to improve the ratio of RI in VMs prepared by an InP, we propose VM trading methods in which idle RI of SPs with VM demand falling below the number of contracted RI are transferred to SPs with VM demand exceeding the number of contracted RI. As the VM trading mechanisms, we investigate two approaches: RI with self-help effort (RISE) and RI with mutual aid (RIMA). Through numerical evaluation using the demand pattern of commercial VoD service, we show that the proposed VM trading methods decrease the number of VMs required for ODI by about 50% to 100% and increase the ratio of RI by about 15% to 85%.

中文翻译：

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公有云中的虚拟机交易

根据公有云服务的需求，通过从基础设施提供商（InP）获取虚拟机（VM），服务提供商（SP）可以弹性地为用户提供网络服务。作为虚拟机的计费方式，预留实例（RI）和按需实例（ODI）被广泛使用。对于 InP 来说，RI 比 ODI 更可取，因为它易于估算长期收入，避免出现空闲 VM 资源的风险，以及降低收费成本。在本文中，为了提高由 InP 准备的 VM 中 RI 的比率，我们提出了 VM 交易方法，其中 VM 需求低于签约 RI 数量的 SP 的空闲 RI 转移到 VM 需求超过签约数量的 SP RI。作为 VM 交易机制，我们研究了两种方法：自助式 RI (RISE) 和互助式 RI (RIMA)。