Hi Sylvain,

   We don't support log report for more than 30 days at the moment. We'll take this as a request and check where this can be accommodated in our roadmap.

Btw, any particular reason for asking this request. We have the Availability summary report which you can get for any monitor. It gives a availability summary along with downtime details for the selected time period. 

-Jasper

Product Manager, Site24x7