Full Virus Scan on File Server

I have a file server with about 5TB of data on it. I run a full virus scan every Weds. night. The problem is that it takes about 4 days to run and it kill sthe proc so my users are affected. My question would be: What is the standard for doing full virus scans on file servers of this size? I don’t see how it would be acceptable to affect the users like this but I don’t see many options. Thanks for any info!