F

FC/FibreChannel

Fibre Channel, or FC, is a high-speed network technology (commonly running at 1, 2, 4, 8, 16, 32, and 128 gigabit per second rates) primarily used to connect computer data storage to servers. Fibre Channel is mainly used in storage area networks (SAN) in enterprise storage. Fibre Channel networks are known as a Fabric because they operate in unison as one big switch. Fibre Channel typically runs on optical fiber cables within and between data centers.

Most block storage runs over Fibre Channel Fabrics and supports many upper level protocols. Fibre Channel Protocol (FCP) is a transport protocol that predominantly transports SCSI commands over Fibre Channel networks. Mainframe computers run the FICON command set over Fibre Channel because of its high reliability and throughput. Fibre Channel is the most popular network for flash memory being transported over the NVMe interface protocol.

The following Variants of FC are an overview of FC native speeds:

Fibre Channel Variants

NAME Line-rate Line coding Nominal throughp. per direction; MB/s Net throughp. per direction; MB/s Availability
1GFC 1.0625 8b10b 100 103.2 1997
2GFC 2.125 8b10b 200 206.5 2001
4GFC 4.25 8b10b 400 412.9 2004
8GFC 8.5 8b10b 800 825.8 2005
10GFC 10.51875 64b66b 1,200 1,239 2008
16GFC “Gen 5” 14.025 64b66b 1,600 1,652 2011
32GFC “Gen 6” 28.05 64b66b 3,200 3,303 2016
128GFC “Gen 6” 4×28.05 64b66b 12,800 13,210 2016

For more information please check the Wikipedia entry for SAN: https://en.wikipedia.org/wiki/Fibre_Channel where most of the info in this entry is from.

FUSE

FUSE (Filesystem in Userspace) is an interface for userspace programs to export a filesystem to the Linux kernel. The FUSE project consists of two components: the fuse kernel module (maintained in the regular kernel repositories) and the libfuse userspace library (maintained in this repository). libfuse provides the reference implementation for communicating with the FUSE kernel module.

A FUSE file system is typically implemented as a standalone application that links with libfuse. libfuse provides functions to mount the file system, unmount it, read requests from the kernel, and send responses back. libfuse offers two APIs: a “high-level”, synchronous API, and a “low-level” asynchronous API. In both cases, incoming requests from the kernel are passed to the main program using callbacks. When using the high-level API, the callbacks may work with file names and paths instead of inodes, and processing of a request finishes when the callback function returns. When using the low-level API, the callbacks must work with inodes and responses must be sent explicitly using a separate set of API functions.