Hi Tom: Ive added some new settings to GribServiceProvider that allows apps to control this behavior. GribServiceProvider.setIndexExtendMode(GribServiceProvider.IndexExtendMode.rewrite) will set the mode to rewrite the index whenever the original file length changes. It will be in the next 4.0 release. Im not yet sure what the default will be, best if IDV sets or allows user to set i guess. Ticket Details =================== Ticket ID: VKB-103067 Department: Support netCDF Java Priority: Normal Status: Open