The following is a great suggestion from Grant.
If you are using Archival-Style Transaction Logging and the Transaction Logs are not backed up frequently enough or if the backup solution fails and does not backup and flag the backed up log extents as free, this can lead to the drive filling up entirely and crashing Domino.
Here are some steps for how to set up an Event Generator monitoring for low disk space on your Transaction Log drive and then to send you an email so you have a chance to sort something out before it fills up the drive and crashes your server. For example, to monitor your E:\ drive you would do the following steps.
Open events4.nsf (Monitoring Configuration) database and open the "Event Generators" -> "Statistics" view, the click the "New Statistic Event Generator" button.
On the Basic tab, select the server to monitor and point to it from the drop-down list.
In the "Statistic to Monitor" section, choose "Single Instance Statistic" and select your drive letter from the drop-list. Choose the "Monitor as a number of bytes" option. See pic:
On the Threshold tab set it up as below, this will monitor for approx 5 Gig of space, set it to whatever you are comfortable with.
On the "Other" tab click the Create a new event handler for this event" button.
Click OK to save the Event Generator when prompted. The Handler Wizard will start up, click next and select the "Mail" option.
Select yourself from the drop-down list to receive the email, then click through to the Finish of the Wizard.
That's it! You will now have a corresponding "Event Handler" for that event and if you click on the "By Action" view under Event Handlers you should see a Mail action set to send you an email if ever the E:\ drive gets down to 5 Gig of space, and you'll have a chance to get the problem corrected.