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diff --git a/doc/admin-guide/en-US/markdown/glossary.md b/doc/admin-guide/en-US/markdown/glossary.md index 0febaff8f..0203319b0 100644 --- a/doc/admin-guide/en-US/markdown/glossary.md +++ b/doc/admin-guide/en-US/markdown/glossary.md @@ -1,10 +1,10 @@ Glossary ======== -Brick -: A Brick is the GlusterFS basic unit of storage, represented by an +**Brick** +: A Brick is the basic unit of storage in GlusterFS, 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 + represented by combining a server name with an export directory in the following format: `SERVER:EXPORT` @@ -13,15 +13,22 @@ Brick `myhostname:/exports/myexportdir/` -Cluster +**Client** +: Any machine that mounts a GlusterFS volume. + +**Cluster** : A cluster is a group of linked computers, working together closely thus in many respects forming a single computer. -Distributed File System +**Distributed File System** : A file system that allows multiple clients to concurrently access data over a computer network. -Filesystem +**Extended Attributes** +: Extended file attributes (abbreviated xattr) is a file system feature + that enables users/programs to associate files/dirs with metadata. + +**Filesystem** : 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 @@ -29,7 +36,7 @@ Filesystem Source: [Wikipedia][] -FUSE +**FUSE** : 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 @@ -38,26 +45,38 @@ FUSE Source: [Wikipedia][1] -Geo-Replication +**Geo-Replication** : Geo-replication provides a continuous, asynchronous, and incremental replication service from site to another over Local Area Networks (LAN), Wide Area Network (WAN), and across the Internet. -glusterd +**GFID** +: Each file/directory on a GlusterFS volume has a unique 128-bit number + associated with it called the GFID. This is analogous to inode in a + regular filesystem. + +**glusterd** : The Gluster management daemon that needs to run on all servers in the trusted storage pool. -Metadata +**Infiniband** + InfiniBand is a switched fabric computer network communications link + used in high-performance computing and enterprise data centers. + +**Metadata** : Metadata is data providing information about one or more other pieces of data. -Namespace +**Namespace** : 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. -Open Source +**Node** +: A server or computer that hosts one or more bricks. + +**Open Source** : 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 @@ -76,7 +95,7 @@ Open Source Source: [Wikipedia][2] -Petabyte +**Petabyte** : 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- @@ -89,7 +108,7 @@ Petabyte Source: [Wikipedia][3] -POSIX +**POSIX** : 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 @@ -97,34 +116,79 @@ POSIX Unix operating system. Gluster exports a fully POSIX compliant file system. -RAID +**Quorum** +: The configuration of quorum in a trusted storage pool determines the + number of server failures that the trusted storage pool can sustain. + If an additional failure occurs, the trusted storage pool becomes + unavailable. + +**Quota** +: Quotas allow you to set limits on usage of disk space by directories or + by volumes. + +**RAID** : 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. -RRDNS +**RDMA** +: Remote direct memory access (RDMA) is a direct memory access from the + memory of one computer into that of another without involving either + one's operating system. This permits high-throughput, low-latency + networking, which is especially useful in massively parallel computer + clusters. + +**Rebalance** +: A process of fixing layout and resdistributing data in a volume when a + brick is added or removed. + +**RRDNS** : Round Robin Domain Name Service (RRDNS) is a method to distribute load across application servers. RRDNS 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 +**Samba** +: Samba allows file and print sharing between computers running Windows and + computers running Linux. It is an implementation of several services and + protocols including SMB and CIFS. + +**Self-Heal** +: The self-heal daemon that runs in the background, identifies + inconsistencies in files/dirs in a replicated volume and then resolves + or heals them. This healing process is usually required when one or more + bricks of a volume goes down and then comes up later. + +**Split-brain** +: This is a situation where data on two or more bricks in a replicated + volume start to diverge in terms of content or metadata. In this state, + one cannot determine programitically which set of data is "right" and + which is "wrong". + +**Translator** +: Translators (also called xlators) are stackable modules where each + module has a very specific purpose. Translators are stacked in a + hierarchical structure called as graph. A translator recieves data + from its parent translator, performs necessary operations and then + passes the data down to its child translator in hierarchy. + +**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. -Userspace +**Userspace** : 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. -Volfile +**Volfile** : Volfile is a configuration file used by glusterfs process. Volfile will be usually located at `/var/lib/glusterd/vols/VOLNAME`. -Volume +**Volume** : A volume is a logical collection of bricks. Most of the gluster management operations happen on the volume. |