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Symlink DSpace
Symlink DSpace is the project of the Institute of Computer Science at
Masaryk University in Brno, Czech Republic. The main purpose of this project is to
modify the original DSpace to work with big files (e.g. video files) in a more
efficient way. The trick lies in using UN*X symbolic links on the file system
layer.
Why Symlink DSpace?
The classic way the original DSpace works is "copying" files into the
assetstore. All the files you want to have in DSpace have to be submitted via
DSpace webUI or imported with help of Import script. From one point of view
both ways works similarly. Submitting takes your locally stored file and
transfers it to the DSpace server where the file is stored. Generally submitting is
copying via network. Importing is copying naturally - files are copied from
one directory to another.
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- so it is necessary to have the files on some "mounted" disk). No copying, no
wasting. Because symlinks are done on the file system layer they are completely
transparent to DSpace - for DSpace they are real files. Disadvantage is only
that it is impossible to submit a file from a network connected computer (a
file that is stored on "unmounted" disk).
Installation
All you have to do to install and use Symlink DSpace is to download
the latest patch (for right version, now 1.3.2 only). In the <tt>$DSPACE_SRC</tt> directory run the following
commands:
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If you want to install DSpace from scratch then it is easy. Just download and
apply the patch (see above) and follow the classic installation steps (as
described in the DSpace manual).
Usage
To do correct symlinking you can't submit/import the real files you want to
have in DSpace!
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Now the file <tt> /disk1/data/video_file.avi </tt> is in DSpace (there is only a symlink in
the assetstore). For details (why submitting text file) see How does it work.
Be careful about the user permissions! The user under which the DSpace is running
has to be able to make symlinks to the file you want to ingest.
Symlink DSpace Import script provides a warning and writes a log file if you don't have
enough permissions to make the symlink. But WebUI doesn't give you any
warning! So if you submit the file via webUI and the file (bitstream) is not
accessible probably you don't have the permissions to make symlink.
Some useful tips
It is not effective to submit to DSpace manually. We are using automatically
generated (via bash shell scripts) structures that are then ingested through
Import script. We can recommend using Symlink DSpace this way.
video@fi
<tt>video@fi</tt> is the project of Faculty of Informatics and
Institute of Computer Science at Masaryk University in Brno, Czech Republic.
The goal of the project
is to store a large amount of video files. These video files are captured
lessons that are taught at the Faculty of Informatics.
How does it work
Symlink DSpace is not a big project. The code for making symlinks is
relatively simple. We found that rewriting the file ingest process in DSpace
is not effective - it is not easy to rewrite the code and it is not
comfortable to do rewriting with every new version of DSpace. It is more
pleasant for the system (and for the developer too 
) to only add some code.
This is the way we have chosen. Unfortunately it requires a small trade-off
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And we are finished. Simple and powerful.
Contact, additional information
For any questions and suggestions please contact us at dspace@muni.cz. Project presentation that were presented at DSUG 2006 (http://dsug2006.uib.no/
) in Bergen can be found http://library.muni.cz/symlinkdspace/ here.
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