Introduction

Often abbreviated "LLStore", the Low Level Storage Interface is a critical component of Fedora.  It stores and provides access to the authoritative copy of all digital object XML (FOXML) and datastreams managed by a Fedora repository.

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Fedora's default LLStore module stores digital object XML and datastreams as individual files in a regular filesystem. However, there are several other options that can be configured.

General Configuration

If you don't want to use the default implementation or configuration options, you must configure the LLStore module before starting Fedora for the first time. Configuration is done within the server/config/fedora.fcfg file, by modifying the class and param values as appropriate for the LLStore implementation you are plugging in:

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Consult the documentation for each plug-in listed below for the specific class name and configuration options supported. Depending on the plug-in you are installing, you may also need to add one or more .jar files to the Fedora webapp's classpath (e.g. WEB-INF/lib).

Plug-Ins Provided by Fedora Commons

Akubra Low Level Storage (New)

Akubra is a newly-developed, generic "blob" storage API. The AkubraLowlevelStorage plug-in is included with Fedora 3.2 and acts as a bridge between Fedora and Akubra, so that Akubra implementations can be used to support low-level storage in Fedora.

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For more extensive information on Akubra, please refer to the Akubra Wiki Space.

Filesystem Low Level Storage (Mature)

This is Fedora's default storage option and requires no additional setup to use. It comes pre-configured with your Fedora installation to store all objects in $FEDORA_HOME/data/objects/, and all datastreams in $FEDORA_HOME/data/datastreams/. Paths are allocated based on the date the item was first created. For example, a datastream created on May 8th, 2009 might be located in the 2009/0508/20/48/ directory.

To change these locations, consult the fedora.fcfg file that came with your Fedora installation and change the indicated param values as desired.

S3 Low Level Storage (Experimental)

This plugin stores all object XML and datastream content on Amazon's Simple Storage System (S3) and serves as a good example of how a LowlevelStorage implementation can be built. However, we do not recommend the use of this plugin in production environments because:

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svn co https://svn.fedora-commons.svn.sourceforge.net/svnroot/fedora-commons/incubator/AmazonS3Storage

Third-Party Plug-Ins

iRODs Low Level Storage

This plugin was developed by the DICE Group and allows Fedora to use iRODs to store digital objects and datastreams.  It is based on the SRB plugin developed by the DART Project (see below).

For more information on this plugin, please visit https://www.irods.org/index.php/Fedora

SRB Low Level Storage

This plugin was developed by the DART Project and allows Fedora to use the Storage Resource Broker (SRB) to store digital objects and datastreams.

For more information on this plugin, please visit http://www.itee.uq.edu.au/~eresearch/projects/dart/outcomes/FedoraDB.php

Sun Honeycomb Low Level Storage

This plugin was developed by Sun Microsystems and allows Fedora to use the StorageTek 5800 Systemto store digital objects and datastreams.

For more information on this plugin, please visit http://opensolaris.org/os/project/honeycomb/

Rebuilder Support

Fedora's Rebuild Utility (fedora-rebuild) provides repository administrators with an automated way to reconstitute Fedora's higher-level indexes (the SQL database and the Resource Index) when upgrading Fedora, migrating to another SQL database, or recovering from inconsistencies.

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