Because of the increased size of some of the basic data types in 64-bit eDirectory environments, it needs an increased memory (approximately 20%) over the same instance of 32-bit eDirectory.
eDirectory running as a 32-bit application can only allocate 4 GB memory to the process which limits the amount of usable cache. The maximum size of the FLAIM cache in a 32-bit eDirectory instance is limited to 2.5 GB. This is not a limitation with 64-bit eDirectory, where process memory can grow beyond 4 GB.
The most significant setting that affects eDirectory performance is the cache. Therefore, 64-bit eDirectory performs better for DIBs larger than 1 GB. It is observed through tests that increasing the hit ratio on larger DIB by increasing the cache results in better performance.
When 32-bit eDirectory runs on a 64-bit operating system, a larger filesystem cache can result in a higher throughput even though the FLAIM cache is limited to 2.5 GB. The operating system automatically uses the available RAM for a filesystem cache.
64-bit eDirectory on a Linux x86_64 bit system performs better than the 32-bit eDirectory.
64-bit eDirectory on Solaris sparcv9 systems did not show significant difference in performance in comparison with the same 32-bit instance of eDirectory. With larger DIB sets, it shows increased performance due to a bigger FLAIM cache.