Access Control Lists
Access Control Lists (ACLs) allows you to assign different permissions for different users or groups even though they do not correspond to the original owner or the owning group.
Brick is the basic unit of storage, represented by an export directory on a server in the trusted storage pool.
A cluster is a group of linked computers, working together closely thus in many respects forming a single computer.
Distributed File System
A file system that allows multiple clients to concurrently access data over a computer network
Filesystem in Userspace (FUSE) is a loadable kernel module for Unix-like computer operating systems that lets non-privileged users create their own file systems without editing kernel code. This is achieved by running file system code in user space while the FUSE module provides only a "bridge" to the actual kernel interfaces.
Gluster management daemon that needs to run on all servers in the trusted storage pool.
Geo-replication provides a continuous, asynchronous, and incremental replication service from site to another over Local Area Networks (LANs), Wide Area Network (WANs), and across the Internet.
Metadata is defined as data providing information about one or more other pieces of data. There is no special metadata storage concept in GlusterFS. The metadata is stored with the file data itself.
Namespace is an abstract container or environment created to hold a logical grouping of unique identifiers or symbols. Each Gluster volume exposes a single namespace as a POSIX mount point that contains every file in the cluster.
Portable Operating System Interface [for Unix] is the name of a family of related standards specified by the IEEE to define the application programming interface (API), along with shell and utilities interfaces for software compatible with variants of the Unix operating system. Gluster exports a fully POSIX compliant file system.
Redundant Array of Inexpensive Disks (RAID) is a technology that provides increased storage reliability through redundancy, combining multiple low-cost, less-reliable disk drives components into a logical unit where all drives in the array are interdependent.
Round Robin Domain Name Service (RRDNS) is a method to distribute load across application servers. It is implemented by creating multiple A records with the same name and different IP addresses in the zone file of a DNS server.
Trusted Storage Pool
A storage pool is a trusted network of storage servers. When you start the first server, the storage pool consists of that server alone.
Applications running in user space don’t directly interact with hardware, instead using the kernel to moderate access. Userspace applications are generally more portable than applications in kernel space. Gluster is a user space application.
A volume is a logical collection of bricks. Most of the gluster management operations happen on the volume.
.vol files are configuration files used by glusterfs process. Volfiles will be usually located at /var/lib/glusterd/vols/volume-name/. Eg:vol-name-fuse.vol,export-brick-name.vol,etc.. Sub-volumes in the .vol files are present in the bottom-up approach and then after tracing forms a tree structure, where in the hierarchy last comes the client volumes.
The machine which mounts the volume (this may also be a server).
The machine which hosts the actual file system in which the data will be stored.
Replicate is generally done to make a redundancy of the storage for data availability.
Once familiar with terminologies, Understand the Architecture of GlusterFS