For n transactions and a group commit of size m, this optimiza tion provides an average of 3nl2m forced-writes savings. In this simple analysis we assumed that only one member of each transaction resides at each node.
A detailed analysis of the group commit optimization is quite complicated since several parameters are involved: 1/0 rate, group size, nvmber of participants, response time, and time to allow the commit group to build up. Such analysis can be found in [4, 28].