Methods for allocating memory for logging data written by a host computer to a source virtual disk and for managing memory allocated to a data log, in a data storage system adapted to maintain redundant data storage sets at a destination location(s) are disclosed. The data storage system maintains a data log that may be activated when a destination volume is inaccessible. During the logging process the system implements an adaptive memory allocation algorithm that adjusts the log memory allocation increment as a function of the velocity of logging data written by the host computer(s). Similarly, during a merge process the system implements an adaptive memory deallocation algorithm that deallocates log memory in response to the velocity of logging data written by the host computer(s) and the velocity of merge data transmitted to the remote system. An amount of memory allocated to logging data may be compared with an amount of memory allocated to corresponding user data and, if greater, the data log terminated.