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layout: default
navsection: installguide
title: Choosing which components to install
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Arvados consists of many components, some of which may be omitted (at the cost of reduced functionality.)  It may also be helpful to review the "Arvados Architecture":{{site.baseurl}}/architecture to understand how these components interact.

table(table table-bordered table-condensed).
|\3=. *Core*|
|"Postgres database":install-postgresql.html |Stores data for the API server.|Required.|
|"API server":install-api-server.html |Core Arvados logic for managing users, groups, collections, containers, and enforcing permissions.|Required.|
|\3=. *Keep (storage)*|
|"Keepstore":install-keepstore.html |Stores content-addressed blocks in a variety of backends (local filesystem, cloud object storage).|Required.|
|"Keepproxy":install-keepproxy.html |Gateway service to access keep servers from external networks.|Required to be able to use arv-put, arv-get, or arv-mount outside the private Arvados network.|
|"Keep-web":install-keep-web.html |Gateway service providing read/write HTTP and WebDAV support on top of Keep.|Required to be able to download files from Keep over plain HTTP in Workbench.|
|"Keep-balance":install-keep-balance.html |Storage cluster maintenance daemon responsible for moving blocks to their optimal server location, adjusting block replication levels, and trashing unreferenced blocks.|Required to free deleted data from underlying storage, and to ensure proper replication and block distribution (including support for storage classes).|
|\3=. *User interface*|
|"Single Sign On server":install-sso.html |Login server.|Required for web based login to Workbench.|
|"Workbench":install-workbench-app.html, "Workbench2":install-workbench2-app.html |Primary graphical user interface for working with file collections and running containers.|Optional.  Depends on API server, SSO server, keep-web, websockets server.|
|"Workflow Composer":install-composer.html |Graphical user interface for editing Common Workflow Language workflows.|Optional.  Depends on git server (arv-git-httpd).|
|\3=. *Additional services*|
|"Websockets server":install-ws.html |Event distribution server.|Required to view streaming container logs in Workbench.|
|"Shell server":install-shell-server.html |Synchronize (create/delete/configure) Unix shell accounts with Arvados users.|Optional.|
|"Git server":install-arv-git-httpd.html |Arvados-hosted git repositories, with Arvados-token based authentication.|Optional, but required by Workflow Composer.|
|\3=. *Crunch (running containers)*|
|"crunch-dispatch-slurm":crunch2-slurm/install-prerequisites.html |Run analysis workflows using Docker containers distributed across a SLURM cluster.|Optional if you wish to use Arvados for data management only.|
|"Node Manager":install-nodemanager.html |Allocate and free cloud VM instances on demand based on workload.|Optional, not needed for a static SLURM cluster (such as on-premise HPC).|