Techniques for selectively utilizing memory available in a redundant host system of a cluster are described. In one embodiment, a cluster of host systems, with at least one redundant host system, with each host system having a plurality of virtual machines with associated virtual machine (VM) reservation memory is provided. A portion of a data store is used to store a base file, the base file accessed by all the plurality of virtual machines. A portion of the memory available in the redundant host system is assigned as spare VM reservation memory. A copy of the base file is selectively stored in the spare VM reservation memory for access by all the plurality of virtual machines.