LoadSim

LoadSim is a Microsoft provided performance measurement tool for Exchange. LoadSim ("Load Simulator") that mimics the effects of Outlook clients saturating the server with requests. LoadSim measures "hits-per-minute", i.e. how many operations per minute the server can support. Thanks to PostPath's drop-in compatibility, LoadSim can be run against the PostPath Server just as it is run against Exchange for performance comparison testing.

In the following test, identical hardware was configured with

a PostPath-on-Linux server and
an Exchange-on-Windows server

The same LoadSim test was carried out against the two setups, and the results compared.

The test reflects a weighted-average result (weighted according to Microsoft's preferences across all the LoadSim functions), with the PostPath server achieving a score of 3272 hits per minute vs. 589 for Exchange. In other words, the PostPath Server achieved a significant performance increase over Exchange in terms of hits-per-minute. The other comparisons show the relative throughput of some of the most commonly used operations, specifically sending and replying to messages, reading messages, and moving (or deleting) messages. Again, the PostPath Server emerges as dramatically faster.

Of course, we should note that many factors can affect performance - results will vary in different situations.

Technical Note
Server hardware used for Exchange and PostPath Server: CPU: Intel Pentium 4E, 3.4 GHz; MotherBoard: MSI 865PE Neo2-PS (MS-6728v2.0); Memory: 1GB (4 x 256 MB of Samsung M3 68L3223FTN_CCC); hard-drive: 80 GB Western Digital (WD800BB - 55JKA0).
LoadSim was run in saturation mode for 5 minutes. Exchange software used was Exchange 2003 and Windows 2003 using NTFS, all with all latest patches as at April 2006. PostPath was RedHat Enterprise Linux 4.2 using XFS filing system. Both servers were configured with default settings.
The "Sending" number includes the following LoadSim tests: send, reply, reply-all, forward. The "Reading" number reflects the LoadSim "Read" test. The "Moving" number includes the LoadSim move, delete, and deliver tests. The average result shows results across all tests weighted according to Microsoft's weighting algorithm.