Techniques for ensuring sufficient available storage capacity for data resynchronization or data reconstruction in a cluster of a hyper-converged infrastructure (HCI) deployment are provided. In one set of embodiments, a computer system can receive a request to provision or reconfigure an object on the cluster. The computer system can further calculate one or more storage capacity reservations for one or more host systems in the cluster, where the one or more storage capacity reservations indicate one or more amounts of local storage capacity to reserve on the one or more host systems respectively in order to ensure successful data resynchronization or data reconstruction in the case of a host system failure or maintenance event. If placement of the object on the cluster will result in a conflict with the one or more storage capacity reservations, the computer system can deny the request to provision or reconfigure the object.