We've confirmed that all systems are back to normal with no customer impact as of 10/03, 11:44 AM UTC. Our logs show the incident started on 10/03, 06:38 AM UTC and that during the 5 hours and 6 minutes that it took to resolve the issue 25% of customers in West Europe may have seen duplication in audit logs and REST API data as well as some data loss.
Root Cause: The failure was due to an upstream component sending duplicate sets of data.
Incident Timeline: 5 Hours & 6 minutes - 10/03, 06:38 AM UTC through 10/03, 11:44 AM UTC
We understand that customers rely on Azure Log Analytics as a critical service and apologize for any impact this incident caused.