Elastic block storage (EBS) with the storage-compute disaggregated architecture stands as a pivotal piece in today's cloud. EBS furnishes users with storage capabilities through the elastic solid-state drive (ESSD). Nevertheless, despite the widespread integration into cloud services, the absence of a thorough ESSD performance characterization raises critical doubt: when more and more services are shifted onto the cloud, can ESSD satisfactorily substitute the storage responsibilities of the local SSD and offer comparable performance? In this paper, we for the first time target this question by characterizing two ESSDs from Amazon AWS and Alibaba Cloud. We present an unwritten contract of cloud-based ESSDs, encapsulating four observations and five implications for cloud storage users. Specifically, the observations are counter-intuitive and contrary to the conventional perceptions of what one would expect from the local SSD. The implications we hope could guide users in revisiting the designs of their deployed cloud software, i.e., harnessing the distinct characteristics of ESSDs for better system performance.

翻译：采用存储-计算分离架构的弹性块存储（EBS）是当今云环境中的关键组件。EBS通过弹性固态硬盘（ESSD）为用户提供存储能力。然而，尽管ESSD已广泛集成于云服务中，但其性能特征的缺失引发了一个关键疑虑：当越来越多的服务迁移至云端时，ESSD能否令人满意地替代本地SSD的存储职责并提供可比性能？本文首次针对该问题，对来自亚马逊AWS和阿里云的两款ESSD进行了性能表征。我们提出了云端ESSD的隐性契约，其中包含四项观测结果及对云存储用户的五项启示。具体而言，这些观测结果与人们对本地SSD的传统认知相悖且反直觉。我们希望这些启示能够引导用户重新审视其已部署云软件的设计，即通过利用ESSD的独特特性来提升系统性能。