cluster


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Related to cluster: Cluster analysis, Cluster Headaches

cluster,

in astronomy: see star clusterstar cluster,
a group of stars near each other in space and resembling each other in certain characteristics that suggest a common origin for the group. Stars in the same cluster move at the same rate and in the same direction.
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; galaxygalaxy,
large aggregation of stars, gas, dust, and usually dark matter, typically containing billions of stars. Recognition that galaxies are independent star systems outside the Milky Way came from a study of the Andromeda Galaxy (1926–29) by Edwin P.
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.

cluster

A group of stars whose members are sufficiently close to each other to be physically associated. Clusters range from dense congregations of many thousands of stars to loose groups of only a few stars. Current theories of stellar evolution suggest that stars form in associations, whose densest groupings remain bound as clusters while the other stars disperse; this view is supported by the relatively well-defined Hertzsprung–Russell diagrams of clusters, which indicate that cluster members are of essentially the same composition and age (see also turnoff point). Because the stars in a cluster are all at approximately the same distance, the observed differences in appearance are believed to be due mainly to differences in mass. An estimate of distance is obtained from the technique of main-sequence fitting. See globular cluster; open cluster.

Cluster

An ESA mission to study in three dimensions the shape and dynamic behavior of small-scale structures in the Earth's plasma environment. In effect, Cluster is examining ‘space weather’ – that is, the interaction between the particles of the solar wind and the Earth's magnetosphere. The mission consists of four identical 500-kg satellites, carrying the same 10 instruments. The satellites were carried into space in two pairs by Russian-made Soyuz rockets during the summer of 2000. The first pair, nicknamed Salsa and Samba, were launched July 16, followed by the second pair, Rumba and Tango, launched Aug. 9. The Cluster craft were scheduled to operate until 2005. The mission, which was designated Cluster II, was the replacement for an earlier failed mission. The original Cluster satellites were to have been sent into space together in June 1996, on an Ariane-5 rocket, but were destroyed when the rocket unexpectedly tilted and broke up soon after liftoff.

Cluster

Any configuration of elements that are grouped or gathered closely together.

cluster

[′kləs·tər]
(astronomy)
(computer science)
In a clustered file, one of the classes into which records with similar sets of content identifiers are grouped.
A grouping of hardware devices in a distributed processing system.
A group of disk sectors that is treated as a single entity by the operating system
(engineering)
A pyrotechnic signal consisting of a group of stars or fireballs.
A grouping of rocket motors fastened together.
(ordnance)
A collection of small bombs held together by an adapter for dropping.

cluster

i. Several bomblets forming part of a bomb as in cluster bomb. Once a bomb is released from the aircraft, individual bomblets are dispensed by the bomb.
ii. Two or more parachutes linked to support a single load.
iii. Several engines controlled by a single throttle.

cluster

1. Astronomy an aggregation of stars or galaxies moving together through space
2. Chem
a. a chemical compound or molecule containing groups of metal atoms joined by metal-to-metal bonds
b. the group of linked metal atoms present

cluster

(architecture)
Multiple servers providing the same service. The term may imply resilience to failure and/or some kind of load balancing between the servers. Compare RAIS.

cluster

(file system)
An elementary unit of allocation of a disk made up of one or more physical blocks.

A file is made up of a whole number of possibly non-contiguous clusters. The cluster size is a tradeoff between space efficiency (the bigger is the cluster, the bigger is on the average the wasted space at the end of each file) and the length of the FAT.

cluster

(1) Two or more systems working together. See clustering.

(2) Also called an "allocation unit" or "file allocation unit," it is a number of storage sectors treated as a unit. A cluster is the smallest unit of storage the operating system's file system can manage. That means if a 1KB file is stored in a system with a 4KB cluster (see table below), the 1KB file takes up 4KB of disk space.

Following are the cluster sizes for the various Windows file systems starting with Windows XP. When FAT32 came out, the reduction of cluster sizes from 16KB and 32KB down to 4KB saved a lot of space for small files. See file system, FAT, FAT32 and lost cluster.

                  Cluster Size Drive       FAT16       FAT32  Size        (1984)      (1996)

     8-32MB     512 bytes  --
    32-64MB     1KB         512 bytes
    64-128MB    2KB         1KB
   128-256MB    4KB         2KB
   256-512MB    8KB         --
 512MB-1GB     16KB         --
     1-2GB     32KB         --
     2-4GB     64KB         --
 256MB-8GB      --          4KB
     8-16GB     --          8KB
    16-32GB     --         16KB

                NTFS(1993)

     7-512MB    4KB
 512MB-1GB      4KB
   1GB-2GB      4KB
   2GB-2TB      4KB
   2TB-16TB     4KB
  16TB-32TB     8KB
  32TB-64TB    16KB
  64TB-128TB   32KB
 128TB-256TB   64KB
References in periodicals archive ?
Both in the gaps between galaxies that are clustered and in the lonelier neighborhoods outside those clusters, magnetic fields are remarkably strong, a scientific team reports.
1 enhances cluster and job management and supports the latest processor and interconnect technologies featured in HP Cluster Platforms, including the HP BladeSystem c-Class portfolio.
Scalable shared data storage, equally accessible by all nodes in the cluster, is an obvious vehicle to provide the requisite data storage and access services to compute cluster clients.
Chiba City will help advance open source projects such as VACM, the VA Cluster Manager, and will benefit the community immensely.
Simulations suggest monster clusters may lurk in the distant universe
Not available with existing cluster schedulers, Virtual Cluster data and analytics provide cluster owners with deep insight into cluster capacity and utilization information.
Clustered Failover/Fastback: Automatic failover enables computing resources to be transparently redirected across the cluster to alternative ports or controllers without business interruption.
The unseen matter forms small lumps that coalesce into bigger lumps, in the same way that visible stars group into galaxies and galaxies assemble into clusters.
Windows Compute Cluster Server 2003 is expected to be available on HP Cluster Platforms in the second half of the year.
These technology advances have removed many of the impediments encountered by early adopters of cluster computing technology.
He hopes other researchers will try to make a solid using this cluster, but he notes that scientists must first develop better ways to make large quantities of clusters in specific sizes.
Voltaire solutions supporting Microsoft Windows Compute Cluster Server 2003 are now available through Voltaire's original equipment manufacturer (OEM), integrator and reseller channels.