Cloud Computing Systems (CCSs) provides a computing capability through the Internet. It enables organizations or individuals to have a computing power without deploying and maintaining their own Information Technology infrastructure. As a cloud is realized on a vast scale cloud, it consumes an enormous amount of energy. Migration pattern, where several Virtual Machines (VMs) can be placed on a minimum number of active Physical Machines is called VMs Consolidation (VMC). Thus, this technique can be a practical approach for balancing electricity consumption and other QoS requirement in CCSs. Especially, VMC must meet the service quality requirements, minimization of both energy consumption and Service Level Agreement violation in CCSs. This paper presents a systematic survey of VMC in CCSs with particular attention to the VMC phases, metrics, objectives, migration patterns, optimization methods, and evaluation approaches of VMC. Our review study is presented based on the past literature with a focus on the type of hardware metrics, software metrics, objectives, algorithms, and architectures of VMC in CCSs.

云计算系统（CCS）通过Internet提供计算能力。它使组织或个人无需部署和维护自己的信息技术基础架构即可拥有计算能力。由于云是在大规模云上实现的，因此会消耗大量能量。在最小数量的活动物理机上可以放置多个虚拟机（VM）的迁移模式称为VMs Consolidation（VMC）。因此，该技术可能是在CCS中平衡功耗和其他QoS要求的实用方法。特别是，VMC必须满足服务质量要求，将CCS中的能耗和服务水平协议违规降至最低。本文对CCS中的VMC进行了系统的调查，并特别关注VMC的阶段，指标，VMC的目标，迁移模式，优化方法和评估方法。我们的回顾研究是基于过去的文献提出的，重点是CCS中VMC的硬件指标，软件指标，目标，算法和体系结构的类型。