I think UREs due to problems with medium (magnetic layer) can be eliminated to arbitrarily small rate with more and better ECC. However I think (probably small)

I think UREs due to problems with medium (magnetic layer) can be eliminated to arbitrarily small rate with more and better ECC. However I think (probably small) part of the total URE rate are randomly occurring errors due to intermittent mechanical and electronic failures, mostly due to random environment influences. Eliminating those would require technology improvement beyond more ECC on the platter. Probably more ECC and higher quality of all components along the whole datapath. Maybe the above is wrong because UREs are just the unrecoverable medium errors. I can't find the official definition of URE rate.