I am sorry to say that I am unlikely to be able to solve your problem since I cannot reproduce it. The fact that you are getting an IO failure means that when ncdump is run by php in that server environment, ncdump is not able to access that url or that in reading it it gets a read failure. Why that error should occur in only that environment is a mystery to me. Again, sorry that I cannot solve the problem. If you get any more information, please let me know. =Dennis Heimbigner Unidata Ticket Details =================== Ticket ID: DOE-704686 Department: Support netCDF Priority: Normal Status: Open