How to monitor duration of very long events?

[floko]

Hi all!
How would you go on monitoring the duration that a service is in state "Connected"?
Let's say I have 10 Instances of a service running on a Server, each instance writes its own logfiles.
At some point of time, another piece of software connects to one of these instances. this results in a certain message in this instance's logfile, i.e. Connected.
At some other time, another piece of software connects to a different instance of the service, which again results in a Connected message for this service.

I would like to get the duration of each instance that it is in state connected. If there was a Disconnect in-between, I am not interested in the overall sum, only in the current duration if it is Connected.

The problem here is that the Connected state can last very long, i.e. over 100 days, while my max bucket size is only 35 days.

So, is it even possible in these circumstances? If so, how?
Thanks!

[HiroshiSatoh · Accepted solution]

It is recommended to save the key fields (start time, disconnect time, instance name, state) in the LOOKUP file.
Updates the LOOKUP file when logging instance connection or disconnection is logged.

[floko]

Sorry for answering so late.
Your suggestion with lookup files was very helpful.
I marked it as Accepted Answer! 🙂