Report Service error

Yesterday I helped a developer troubleshoot an issue he was experiencing with a report. The report is hosted on a SQL 2008 instance used for testing and was being viewed in a Win Form application using the Report Viewer control. We congigured the viewer control opens the reports as an image since this would be what the client sees when they print it. He couldn't tell me the exact error message but it referred to not being able to find the stream. He also stated that the report worked fine if he ran it with less data.

I first checked the execution log table in the report database and I saw he was getting a rendering error. Next I had him rerun the report in the viewer. This time he received a generic error saying that there was a problem. But if he clicked the page layout button to render the report in HTML the report ran fine.

My next step was to check the logs on the report server instance. Sure enough I found the error. It was an IO issue; not enough space on the drive. Luckily this was on a testing server and not production.

Now the testing server is not set up the same as a production server. This box is a jumble of programs and databases, running multiple SQL instances for 2000, 2005, and 2008. The report server temp database is on the same drive as the report server database and the error logs and dumps. At the time I saw this the drive had about 100 MB free. And while 100 MB isn't a lot of space nowadays, I would have thought it would have been enough to run the report (it had over 800 pages when we freed up space for it).

At this point I'm not sure where that image is being produced, in the reports database or the report temp database. I've never dug into the report temp db before. I'd like to head from anyone who has had similar problems, or can show me where else I should be looking.