Using the ArcMap 10.1 Network Analyst Location-allocation solver, I am attempting to allocate 171,126 Census Output Area centroids (demand points) to 2624 secondary school (facilities) using distance as impedance, school-age population as demand point weight and school capacity as facility capacity. The L-A problem type I am using is the "maximise capacitated coverage" problem type. I require all schools to be included in the solution so I have set the "facility type" as "required" and the number of "facilities to choose" to 2624.
When I run the solver, no error messages are initially displayed and the process appears to be working. Arc takes approximately 5 minutes to "Compute OD lines" for all objects. The editing of the OD cost matrix values for use in the location-allocation problem type then appears to be carried out in a minute or two. Following this, "Locating facilities" briefly flashes up next to the progress bar before "Solve failed" is displayed. No error messages are produced.
From looking into the algorithms used in the process, it would appear that the solve failure occurs at the stage of the operation where (to quote ESRI help: "the location-allocation solver then generates a set of semi-randomized solutions and applies a vertex substitution heuristic (Teitz and Bart) to refine these solutions creating a group of good solutions".
Is anybody able to explain what may be causing this error and perhaps suggest some way I may be able to get around it?