Evolution of the CMS Computing Model towards Phase-2

The success of the physics program of the Compact Muon Solenoid (CMS) experiment critically depends on the availability of sufficient computing resources to store, process, and analyze data efficiently. The luminosity of HL-LHC and the upgraded detector promise scientific results of great impact. We describe the challenges posed by the event rates and complexity in the HL-LHC era on offline processing as well as the plans for the future computing model of the CMS experiment. We estimate the computing resources needed and provide a description of the modeling and assumptions used to determine those estimates. We also highlight the areas of research and development where we need to make investments, in particular in improving data processing applications and software related to the handling of the computing infrastructure. \ \noindent\it{N.B. This document is based on the written response of the CMS experiment to the charge of the LHCC Computing Model Review round in May 2020 and has been minimally edited for content and presentation.}