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Being a GridPP user isn't always straightforward. You might have thousands of CPU and terabytes of disk at your fingertips, but can you get your job to work on all of them - or any of them? Although there are many more grid users than there used to be, getting started on a grid, and getting it to do what you want, are still not for the faint hearted. Fortunately, there are people trying to make it easier. One of them is Steve Lloyd, GridPP's Collaboration Board Chair. As part of his work on the LHC's ATLAS experiment, Steve has been sending jobs to grids such as GridPP and EGEE for years. But although many of his jobs went off without a hitch, he found some just kept failing, even though they were sent to a working site that passed all the grid's tests. Six months ago, he decided to find out why. And as Chair of GridPP, he was in a position to get problems fixed. The result of Steve's work is a suite of three test jobs that run hourly on GridPP sites. The complexity of these test jobs range from submitting "Hello World" to analyzing a file of particle physics data using the latest ATLAS software. Details of the jobs and results are at its Web site. Steve explains: "When I first started running these tests, their success rate was only around 50%. I'd get a massive range of problems: broken resource brokers, difficulties with the information system, proxy certificates timing out, sites that didn't have the latest version of the ATLAS software, and even sites without the required compiler." Using the detailed log files provided by Steve's test jobs, and with the aid of the GridPP Deployment Team, each grid site got to the bottom of their problems. The test jobs now run at a 90% success rate - the plot below shows the sustained increase over 2007. This gives Steve some hope for future grid users. "I used to wonder how users would ever be able to analyse the ATLAS data on the grid. Now I'm more hopeful - but we've still got a lot of work to do."