Paper Title: Persistent Memory Instead of Cache for Metadata in Crimson

Paper Abstract: Crimson is a project to refactor ceph osd based on the shared-nothing seastar framework. The current Crimson SeaStore is mainly targeting NAND SSD because of their high performance-price ratio and is heavily optimized for random read and sequence write patterns. This presentation will extend the SeaStore framework to support other non volatile storage, mainly focusing on byte addressable random access devices such as optane Persistent Memory (PMEM). Current SeaStore support NAND SSD and use DRAM Cache to transient cache data, and use segment manager which partition device into segments and uses a cleaner to reclaim space; In this scenario, PMEM is as a persistent storage for metadata which is updated synchronously like memory since it has nearly the same speed and latency of DRAM, so needn't load metadata into DRAM Cache and also introduce a new PMEM manager which uses bitmap to allocate space. They still need to share some common paths, such as transaction commit and delta processing, with adjustments needed to adapt to the specialized I/O patterns.

Paper Author: Chunmei Liu, Senior Engineer, Intel

Author Bio: Chunmei Liu is a senior Cloud Orchestration Software Engineer in Intel System Software Engineering Group, who has over 15 years experience in network, virtualization and storage, such as Lenovo Firewall, open source virtualization Xen, Intel virtualization EVMM, Android, EMC CoprHD and CEPH. Currently she is working on SDS(software designed storage) project named CEPH, working on Crimson which is an improvement of CEPH OSD.