Here's an issue that a couple of customers have seen recently.  To prevent IAG logfiles from getting to large and filling your disk, it cleans the logs up periodically.  You can control this from the IAG console menu - Admin/Advanced Configuration.  Here you can control the logfile size at which IAG starts its cleanup, and the size of logs that you want IAG to stop at.  By default IAG will start cleaning up the oldest logs when logfiles reach 100Mb and stop when they are reduced to 50Mb, but on a busy IAG server you may want to increase this significantly.

The problem that you may see is that IAG appears not to honour the 'low water mark' and continues to delete files.  This may cause problems when you come to run Web Monitor reports and find that logfiles have been cleaned up from the \Whale-Com\e-Gap\logs\Events\ folder

This 'excess cleanup' occurs because the \Events\ directory is not the only place that IAG stores logfiles.  The IAG Logfile size is calculated based on these locations:

\whale-com\e-gap\logs\
\whale-com\e-gap\logs\Events\
\windows\system32\logfiles\w3svcX\

If you have any logfiles in either \logs\ or any of the IIS W3SVC log directories, these will count against the high and low water marks.  So you should see that even though you have less logs in \Events\ than you might expect, the overall size of the logs on the system after a cleanup will exactly match the low water mark.

If this is causing you problems when you run Web Monitor reports you should either:

1. Set your Log Cleanup settings to use larger values (rarely a problem with todays hard disks) or;

2. Make sure that you clean up \logs\ and \W3SVCX\ directories regularly.