FLASH OPTIMIZED, LOG-STRUCTURED LAYER OF A FILE SYSTEM

摘要

A flash-optimized, log-structured layer of a file system of a storage input/output (I/O) stack executes on one or more nodes of a cluster. The log-structured layer of the file system provides sequential storage of data and metadata (i.e., a log-structured layout) on solid state drives (SSDs) of storage arrays in the cluster to reduce write amplification, while leveraging variable compression and variable length data features of the storage I/O stack. The data may be organized as an arbitrary number of variable-length extents of one or more host-visible logical units (LUNs) served by the nodes. The metadata may include mappings from host-visible logical block address ranges (i.e., offset ranges) of a LUN to extent keys, as well as mappings of the extent keys to SSD storage locations of the extents. The storage location of an extent on SSD is effectively “virtualized” by its mapped extent key (i.e., extent store layer mappings) such that relocation of the extent on SSD does require update to volume layer metadata (i.e., the extent key sufficiently identifies the extent).

主权项

1. A method comprising:
organizing a storage array of solid state drives (SSDs) coupled to a node as at least one redundant array of independent disks (RAID) group; organizing data and metadata on the SSDs in a sequential log-structured layout, the data stored as extents of a logical unit (LUN) served by the node; gathering the extents to form at least one stripe written as a write operation that spans all of the SSDs in the RAID group; and controlling a frequency and a size of the write operation to sustain a streaming bandwidth to the SSDs and to override garbage collection in the SSDs.