In the upcoming weeks, Blizzard will be testing the effect of a live maintenance, where regular maintenance tasks are run during off-peak hours with the realms live. On Tuesday, December 26 there will be no scheduled downtime for weekly maintenance. Blizzard will perform all necessary maintenance tasks while the realms are live. Blizzard is anticipating the possibility that they may need to perform rolling restarts off-peak if they find that a realm restart is necessary. However, the downtime for each realm is estimated at less than 10 minutes if it was required.
Blizzard Entertainment.