A cooling canister includes a canister body and a sealing surface that seals with a subset of servers mounted in a rack. A cooling canister facilitates airflow isolation between subsets of servers mounted in a rack and is configured to couple with one or more fans that direct airflow through the subset of servers coupled with the cooling canister. In some embodiments, a cooling canister includes louvers configured to restrict airflow through empty rack slots to which the cooling canister is coupled.