The letters in the value field can be in any order. Each letter turns on a different logging mode. Each letter's actual function is as follows for MSI version 1.1:
o - Out-of-disk-space messages
i - Status messages
c - Initial UI parameters
e - All error messages
w - Non-fatal warnings
a - Start up of actions
r - Action-specific records
m - Out-of-memory or fatal exit information
u - User requests
p - Terminal properties
+ - Append to existing file
! - Flush each line to the log
x - Extra debugging information. The "x" flag is available only on Windows Server 2003 and later operating systems, and on the MSI redistributable version 3.0, and on later versions of the MSI redistributable.
"*" - Wildcard, log all information except for the v and the x option. To include the v and the x option, specify "/l*vx".
Note This should be used only for troubleshooting purposes and should not be left on because it will have adverse effects on system performance and disk space. Each time you use the Add/Remove Programs tool in Control Panel, a new Msi*.log file is created.
Enable Windows Installer logging with Group Policies
You can enable logging with Group Policies by editing the appropriate OU or Directory Group Policy. Under Group Policy, expand Computer Configuration, expand Administrative Templates, expand Windows Components, and then select Windows Installer.
Double-click Logging, and then click Enabled. In the Logging box, enter the options you want to log. The log file, Msi.log, appears in the Temp folder of the system volume.
For more information about MSI logging, please see Windows Help. To do so, search using the phrase "msi logging" and select "Managing options for computers through Group Policy".
Note The addition of the "x" flag is available natively on Windows Server 2003 and later operating systems, and on the MSI redistributable version 3.0, and on later versions of the MSI redistributable.