C# Cookbook

6.8. Changing the Maximum Size of a Custom Event Log

Problem

Custom event logs are created with a default maximum size of 512K. For some applications, this default may be too small or even too large. You need a way of programmatically modifying this size. If you are a system administrator, you might need to write a utility to modify this value.

Solution

There is no direct way of modifying the maximum size of an event log. However, the following method makes use of the registry to circumvent this limitation:

using System;
using Microsoft.Win32;

public void SetCustomLogMaxSize(string logName, int maxSize)
{
    RegistryKey key = Registry.LocalMachine.OpenSubKey
      (@"SYSTEM\CurrentControlSet\Services\Eventlog\" + logName, true);
    if (key == null)
    {
        Console.WriteLine(
          "Registry key for this Event Log does not exist.");
    }
    else
    {
        key.SetValue("MaxSize", maxSize);
        Registry.LocalMachine.Close( );
    }
}

Discussion

The FCL classes devoted to making use of the event log contain most of the functionality that a developer will ever need. Yet there are some small items that are not directly accessible using the event log API in the FCL. One of these is the manipulation of the maximum size of an event log. Event logs are initialized to a maximum size of 512K, after which the event log entries are overwritten by default.

There are cases where an application may produce many or very few entries in an event log. In these cases, it would be nice to manipulate the maximum size of an event log so that memory is used ...