1. A system for tracking pool storage space reservations, the system comprising: at a storage entity having a pool of data storage space for storing data, the data storage space being divided into a plurality of slices: one or more portions of non-volatile memory, different from the data storage space, for storing slice reservation statistics and information about requests that affect slice reservation statistics, wherein the slice reservation statistics include information for determining an amount of reserved, unallocated slices; and a control module, implemented by a processor, for receiving an allocation or de-allocation request that affect slice reservation statistics, storing information about the allocation or de-allocation request in the portion of non-volatile memory, wherein storing the information about the allocation or de-allocation request in the portion of non-volatile memory is an atomic operation such that partial storage of the information is prevented, performing the allocation or de-allocation request, and updating the slice reservation statistics and clearing the information about the allocation or de-allocation request in the portion of non-volatile memory.