Figure 6–2 shows modify performance on a hypothetical system. As expected, Directory Server offers top modify performance for a given system configuration when the whole data set fits into memory.
For large data sets better performance has been observed when database cache and entry cache are set to their minimum sizes and available memory is left to the operating system for use in allocating file system cache. As shown, performance improves when more of the data set fits into the file system cache.
For medium data sets, modify performance reaches its maximum as all entries fit into file system cache. As suggested in Basic Tuning Recommendations, keeping some database cache available ensures the modifications to remain cached between each database checkpoint.