Message-Id: 201701261140
Time: January 26th, 2017
Affected: Exchange Server, SharePoint
Impact: Malfunctions of access to the e-mail and SharePoint service

This morning at about 9:40 AM, the replacement of the Exchange 2010 Webmail interface with the Exchange 2016 Webmail interface was started after extensive tests and long preparations. The upgrade to the Exchange 2016 Webmail interface was successfully completed with a minimal interruption of approximately five minutes. After a short time, unexpected technical problems occured. For increased operational reliability, the webmail access under https://email.gwdg.de is distributed to the Exchange-servers by a pair of a geo-redundant load balancers. These load balancers were brought to their technical CPU performance limit by an unpredictable number of connections. Therefore, the E-Mail and SharePoint services were only partially available throughout the morning. This problem could not be resolved in a timely manner. It was therefore decided to abort the migration to Exchange 2016 and to re-enable the Exchange 2010 Webmail. The CPU-load on the load balancers reduced only slowly and Exchange 2010 Webmail could only be launched with a timely delay.

At the moment the causes for the immense load on the load balancers during the upgrade is being investigated. As soon as the failure analysis is secluded and a new upgrade can be completed successfully, a new date will be announced in due time. This new date will be on a weekend.

Please kindly excuse the disturbance and we truely regret the inconveniences arisen through the limited access to these services.