Provided are a method, system, and article of manufacture, wherein a plurality of processing nodes in a storage system are partitioned into a plurality of logical processing units, and wherein the plurality of logical processing units can respond to I/O requests from a host coupled to the storage system. At least two logical processing units are grouped, wherein data in a first storage coupled to a first logical processing unit of the least two logical processing units is mirrored by data in a second storage coupled to the second logical processing unit of the at least two logical processing units. In response to a failure of the first logical processing unit, an I/O request from the host is responded to via the second logical processing unit.