The process, apparatus, and system estimate the size of a data block in a data buffer to efficiently recover the data block to the memory of a computer. The data block resides in a data buffer prior to being written to a destination medium. If the data block cannot be written to the destination medium, the process, apparatus, and system create a data block size estimate. The data block size estimate may be based on the size of the largest data block in the data buffer. Alternately, the data block size estimate may be based on the size of a data block in the memory of the computer. The computer reserves a memory space proportional to the data block size estimate and recovers the data block to the memory space.