Paper presented at CIDR 2020
Philippe presented our paper looking back at Open-Channel SSDs, their impact on the storage industry and the lessons we learned in the OX project. The paper was presented at the CIDR Conference, held for the first time in Amsterdam.
Open-Channel SSDs are storage devices that let hosts takefull control over data placement and I/O scheduling. In recent years, they have gained acceptance in data centers (e.g., Alibaba) and for computational storage (e.g., Pliops). Open-Channel SSDs require a host-based Flash Translation Layer (FTL) that manages the physical address space theyexpose. Open-source FTLs are now available for Open-Channel SSDs, providing either a generic yet tunable blockdevice interface (e.g., pblk, SPDK, OX-Block), or application-specific FTLs developed for a specific data system (e.g., LightLSM, OX-ELEOS). In this paper, we share our experience developing three of those FTLs in the context of the OX controller. We position Open-Channel SSDs in the SSD landscape and discuss their relevance for data systems. In particular, we argue that Open-Channel SSDs cannot be considered as a uniform class of devices. Our main contribution is a description of the key design decisions we took in OX related to Open-Channel SSDs. We reflect on lessons learned and propose hints for the co-design of data systemsand Open-Channel SSDs.