Was recently checking free space on the C: drive of a server and discovered two HUGE (>400MB) files. ISALOG.BIN and ISALOG.BAK. I wonder what these are? Well :
Tracing takes place in the background, and has a negligible affect on ISA Server performance. A 400 megabyte (MB) file (%windir%\debug\isalog.bin) is created by Service Pack 2 on each computer running ISA Server services, to contain the tracing information.
We recommend that you use the default settings for this feature. However, if you want to modify the tracing mechanism, you can do so through the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ISATrace. To change the size of the file used by tracing, change the value of CircularlLogSizeMB. To disable tracing, change the BootTracing value to 0. This does not delete the file, which has to be deleted manually. After registry changes, restart the computer so that the changes take effect. If you create the registry key before installing Service Pack 2, and set the BootTracing value to 0, the tracing file will not be added during the installation, and tracing will not be enabled.
Interestingly they reside on the C: drive of our server even though ISA is on D:. We can't really see the need for them so perhaps we'll reduce their size since space is currently a bit of a premium.
It would have been nice to know that we'd lose almost 1GB of free space by installing ISA 2004 SP2! But now we do right?