Daily Archives: July 18, 2008

About to load test DEF repositories

One of the core aims of the ROAD project is to load test DSpace, EPrints and Fedora repositories to see how they scale when it comes to using them as repositories to archive large amounts of data (in the form of experimental results and metadata). According to ROAR, the largest repositories (housing open access materials) based on these platforms are 191,51059,715 and 85,982 respectively (as of 18th July 208). We want to push them further and see how they fare.

DSpace for instance has in the past suffered from ongoing bad publicity and its own honesty relating to some issues in early versions where they suffered from some instability and slowness under load (user load and content load). One of the downsides of the web (well, of some of it’s users really) is that old reports stay archived on the web, and are read and believed with no consideration of changes that may have taken place in the interim. Many or most of these issues have now been sorted for the sort of scale that used to cause problems (100,000 items to 1/4 million items) and we need to re-evaluate the platform to see where it now breaks. Indeed the following report set out to test DSpace with 1 million items, and found no particular issues:

Testing the Scalability of a DSpace-based Archive, Dharitri Misra, James Seamans, George R. Thoma, National Library of Medicine, Bethesda, Maryland, USA

I’ve not looked very hard, but there was nothing obvious on the first page of Google results about EPrints scalability, but for Fedora I found this useful page: http://fedora.fiz-karlsruhe.de/docs/Wiki.jsp?page=Main

Our new load testing hardware has arrived. We have a standard spec server to perform the testing, and a beefy little number on which to run the repositories:

  • Two quad-core XEON processors
  • 16GB RAM
  • 6TB raw SATA disk (yes its slow, but cheap!)

We’ve not yet decided what tests we’ll run (get in contact if you have any suggestions!), but we have decided we’ll be using SWORD to perform the test deposits it allows us to throw identical packages at all three repositories which provides us with a level playing field.

We’ve done some initial work which showed some of the repositories fell down as soon as we tried to deposit more than a couple of items concurrently using SWORD, and others fell down at 50 concurrent deposits, but these are small implementation issues which have now been fixed, so full testing can start taking place.

More details will be blogged once we start getting some useful comparative data, however seeing as the report cited above took about 10 days to deposit 1 million items, it may be some weeks before we’re able to report data from meaningful tests on each platform.

These results will inform the next stage of the ROAD project which is to choose one of the repositories upon which to build a repository for the Robot Scientist, so the stakes are high!сайт для начинающих копирайтеров