Since 2003 CNAF hosts the main INFN computing center, the Tier-1.
In the data center, besides the Tier-1 and a Tier-2 for the LHCb experiment (logically separated but actually part of the Tier-1 farm) also other resources are hosted: a small HPC cluster, a Tier-3 co-managed with the INFN Bologna Division, the services for the Grid infrastructure as well as INFN national services managed by other CNAF groups and the main GARR PoP.

The LHC experiments represent more than three quarters of the total resources funded at CNAF. They heavily use the Grid technology, on top of which they have built experiment-specific services to better support data management, job management and monitoring.
Besides LHC, the following experiments belonging to the High Energy Physics, Astrophysics and astro-particle domains are also supported at CNAF: CDF, KLOE, NA62, LHCf, ARGO-YBJ, AMS-02, Auger, CTA, Fermi/GLAST, MAGIC, OPERA, PAMELA, ICARUS, Borexino, XENON100, GERDA, DarkSide-50, CUORE, KM3NeT/NEMO, LHAASO, Virgo, JUNO.Support to the BaBar and SuperB experiment was dismissed during 2014.
Recently added experiments are KM3NeT, LHAASO and NA62.

Groups belonging to the Computational Chemistry and Biomedical domains access the center in an opportunistic way through Grid services. Moreover, local theoretical physics and astronomy groups access the Tier-1 resources and services.

Most of these non-LHC user communities use Grid technologies at some level, but in a few cases the activities are performed only locally or using ad-hoc tools. For a more complete description, please refer to the Experiment Support page.

In the following pictures the rapid growth of installed CPU and storage capacity in recent years is shown (CSN1 refers to HEP experiments at accelerator facilities, while CSN2 refers to astro and astro-particle physics experiments).

The Tier-1 operations are structured in 4 groups: the computing farm is managed by the Farming group, the Mass Storage System, the databases and the transfer service are managed by the Data Management group, the LAN and WAN connections of CNAF are managed by the Network group and, last but not least, the facilities of the center are managed by the Facility Management group.

Besides these groups, the Experiment Support group takes care of helping the research groups to efficiently exploit the Data Center infrastructure.

The overall coordination of the operations is responsibility of the Data Center manager, helped by the leaders of the above-mentioned groups and by a rotating deputy.