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<!-- This document was created with Syntext Serna Free. --><!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "docbookV4.5/docbookx.dtd" []>
<chapter>
<title>Glossary</title>
<glosslist>
<glossentry>
<glossterm>Brick</glossterm>
<glossdef>
<para>A Brick is the GlusterFS basic unit of storage, represented by an export directory on a server in the trusted storage pool. A Brick is expressed by combining a server with an export directory in the following format:</para>
<para><code>SERVER:EXPORT</code></para>
<para>For example:</para>
<para><filename>myhostname:/exports/myexportdir/</filename></para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Cluster</glossterm>
<glossdef>
<para>A cluster is a group of linked computers, working together closely thus in many respects forming a single computer.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Distributed File System</glossterm>
<glossdef>
<para>A file system that allows multiple clients to concurrently access data over a computer network.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Filesystem</glossterm>
<glossdef>
<para>A method of storing and organizing computer files and their data. Essentially, it organizes these files into a database for the storage, organization, manipulation, and retrieval by the computer's operating system.</para>
<para>Source: <ulink url="http://en.wikipedia.org/wiki/Filesystem">Wikipedia</ulink></para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>FUSE</glossterm>
<glossdef>
<para>Filesystem in Userspace (<acronym>FUSE</acronym>) 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 <acronym>FUSE</acronym> module provides only a "bridge" to the actual kernel interfaces.</para>
<para>Source: <ulink url="http://en.wikipedia.org/wiki/Filesystem_in_Userspace">Wikipedia</ulink></para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Geo-Replication</glossterm>
<glossdef>
<para>Geo-replication provides a continuous, asynchronous, and incremental replication service from site to another over Local Area Networks (<acronym>LAN</acronym>), Wide Area Network (<acronym>WAN</acronym>), and across the Internet.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>glusterd</glossterm>
<glossdef>
<para>The Gluster management daemon that needs to run on all servers in the trusted storage pool.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Metadata</glossterm>
<glossdef>
<para>Metadata is data providing information about one or more other pieces of data.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Namespace</glossterm>
<glossdef>
<para>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.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Open Source</glossterm>
<glossdef>
<para>Open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology.</para>
<para>Before the term open source became widely adopted, developers and producers used a variety of phrases to describe the concept; open source gained hold with the rise of the Internet, and the attendant need for massive retooling of the computing source code.</para>
<para>Opening the source code enabled a self-enhancing diversity of production models, communication paths, and interactive communities. Subsequently, a new, three-word phrase "open source software" was born to describe the environment that the new copyright, licensing, domain, and consumer issues created.</para>
<para>Source: <ulink url="http://en.wikipedia.org/wiki/Open_source">Wikipedia</ulink></para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Petabyte</glossterm>
<glossdef>
<para>A petabyte (derived from the SI prefix peta- ) is a unit of information equal to one quadrillion (short scale) bytes, or 1000 terabytes. The unit symbol for the petabyte is PB. The prefix peta- (P) indicates a power of 1000:</para>
<para>1 PB = 1,000,000,000,000,000 B = 10005 B = 1015 B.</para>
<para>The term "pebibyte" (<acronym>PiB</acronym>), using a binary prefix, is used for the corresponding power of 1024.</para>
<para>Source: <ulink url="http://en.wikipedia.org/wiki/Petabyte">Wikipedia</ulink></para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>POSIX</glossterm>
<glossdef>
<para>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 (<acronym>API</acronym>), along with shell and utilities interfaces for software compatible with variants of the Unix operating system. Gluster exports a fully <acronym>POSIX</acronym> compliant file system.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>RAID</glossterm>
<glossdef>
<para>Redundant Array of Inexpensive Disks (<acronym>RAID</acronym>) 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.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>RRDNS</glossterm>
<glossdef>
<para>Round Robin Domain Name Service (<acronym>RRDNS</acronym>) is a method to distribute load across application servers. <acronym>RRDNS</acronym> is implemented by creating multiple A records with the same name and different IP addresses in the zone file of a DNS server.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Trusted Storage Pool</glossterm>
<glossdef>
<para>A storage pool is a trusted network of storage servers. When you start the first server, the storage pool consists of that server alone.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Userspace</glossterm>
<glossdef>
<para>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.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Volfile</glossterm>
<glossdef>
<para>Volfile is a configuration file used by glusterfs process. Volfile will be usually located at <filename>/var/lib/glusterd/vols/VOLNAME</filename>.</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Volume</glossterm>
<glossdef>
<para>A volume is a logical collection of bricks. Most of the gluster management operations happen on the volume.</para>
</glossdef>
</glossentry>
</glosslist>
</chapter>
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