mirror of
https://github.com/gluster/glusterdocs.git
synced 2026-02-05 15:47:01 +01:00
5ba15a2b41
* Switch to latest mkdocs * Update travis to python3.6 * Fix for the JS error * Add themedir * Update the template to match latest base.html
216 lines
8.8 KiB
Markdown
216 lines
8.8 KiB
Markdown
Glossary
|
||
========
|
||
|
||
**Access Control Lists**
|
||
: Access Control Lists (ACLs) allow you to assign different permissions
|
||
for different users or groups even though they do not correspond to the
|
||
original owner or the owning group.
|
||
|
||
**Block Storage**
|
||
: Block special files, or block devices, correspond to devices through which the system moves
|
||
data in the form of blocks. These device nodes often represent addressable devices such as
|
||
hard disks, CD-ROM drives, or memory regions. GlusterFS requires a filesystem (like XFS) that
|
||
supports extended attributes.
|
||
|
||
**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 following format:
|
||
|
||
`SERVER:EXPORT`
|
||
For example:
|
||
`myhostname:/exports/myexportdir/`
|
||
|
||
**Client**
|
||
: Any machine that mounts a GlusterFS volume. Any applications that use libgfapi access
|
||
mechanism can also be treated as clients in GlusterFS context.
|
||
|
||
**Cluster**
|
||
: A trusted pool of linked computers working together, resembling a single computing resource.
|
||
In GlusterFS, a cluster is also referred to as a trusted storage pool.
|
||
|
||
**Distributed File System**
|
||
: A file system that allows multiple clients to concurrently access data which is spread across
|
||
servers/bricks in a trusted storage pool. Data sharing among multiple locations is fundamental
|
||
to all distributed file systems.
|
||
|
||
**Extended Attributes**
|
||
: Extended file attributes (abbreviated xattr) is a filesystem feature that enables
|
||
users/programs to associate files/dirs with metadata. Gluster stores metadata in xattrs.
|
||
|
||
**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
|
||
operating system.
|
||
|
||
Source [Wikipedia][Wikipedia]
|
||
|
||
**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 achieved by
|
||
running file system code in user space while the FUSE module provides
|
||
only a "bridge" to the actual kernel interfaces.
|
||
Source: [Wikipedia][1]
|
||
|
||
**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 daemon/service that manages volumes and cluster membership. It is required to
|
||
run on all the servers in the trusted storage pool.
|
||
|
||
**Geo-Replication**
|
||
: 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.
|
||
|
||
|
||
**Infiniband**
|
||
InfiniBand is a switched fabric computer network communications link
|
||
used in high-performance computing and enterprise data centers.
|
||
|
||
**Metadata**
|
||
: 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 usually in the
|
||
form of extended attributes
|
||
|
||
**Namespace**
|
||
: A 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.
|
||
|
||
**Node**
|
||
: A server or computer that hosts one or more bricks.
|
||
|
||
**N-way Replication**
|
||
: Local synchronous data replication which is typically deployed across campus
|
||
or Amazon Web Services Availability Zones.
|
||
|
||
**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-
|
||
(P) indicates a power of 1000:
|
||
|
||
1 PB = 1,000,000,000,000,000 B = 10005 B = 1015 B.
|
||
|
||
The term "pebibyte" (PiB), using a binary prefix, is used for the
|
||
corresponding power of 1024.
|
||
|
||
Source: [Wikipedia][3]
|
||
|
||
**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 utilities interfaces
|
||
for software compatible with variants of the Unix operating system
|
||
Gluster exports a POSIX compatible file system.
|
||
|
||
**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**
|
||
: Quota allows 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.
|
||
|
||
**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**
|
||
: The process of redistributing data in a distributed volume when a
|
||
brick is added or removed.
|
||
|
||
**RRDNS**
|
||
: 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.
|
||
|
||
**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.
|
||
|
||
**Scale-Up Storage**
|
||
: Increases the capacity of the storage device in a single dimension.
|
||
For example, adding additional disk capacity to an existing trusted storage pool.
|
||
|
||
**Scale-Out Storage**
|
||
: Scale out systems are designed to scale on both capacity and performance.
|
||
It increases the capability of a storage device in single dimension.
|
||
For example, adding more systems of the same size, or adding servers to a trusted storage pool
|
||
that increases CPU, disk capacity, and throughput for the trusted storage pool.
|
||
|
||
**Self-Heal**
|
||
: The self-heal daemon that runs in the background, identifies
|
||
inconsistencies in files/dirs in a replicated or erasure coded 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.
|
||
|
||
**Server**
|
||
: The machine (virtual or bare metal) that hosts the bricks in which data is stored.
|
||
|
||
**Split-brain**
|
||
: 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 programmatically which set of data is "right" and
|
||
which is "wrong".
|
||
|
||
**Subvolume**
|
||
: A brick after being processed by at least one translator.
|
||
|
||
**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 receives 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**
|
||
: 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.
|
||
|
||
**Virtual File System (VFS)**
|
||
: VFS is a kernel software layer which handles all system calls related to the standard Linux file system.
|
||
It provides a common interface to several kinds of file systems.
|
||
|
||
**Volume**
|
||
: A volume is a logical collection of bricks.
|
||
|
||
**Vol file**
|
||
: Vol files or volume (.vol) files are configuration files that determine the behavior of the
|
||
Gluster trusted storage pool. It is a textual representation of a
|
||
collection of modules (also known as translators) that together implement the
|
||
various functions required.
|
||
|
||
|
||
[Wikipedia]: http://en.wikipedia.org/wiki/Filesystem
|
||
[1]: http://en.wikipedia.org/wiki/Filesystem_in_Userspace
|
||
[2]: http://en.wikipedia.org/wiki/Open_source
|
||
[3]: http://en.wikipedia.org/wiki/Petabyte
|