This is an Exadata wait event that occurs when a storage cell is starting and discovering disks.
Solutions
This is a normal part of starting up the storage cell in an Exadata system. If there are queries waiting on this, it means the storage cell has not yet started.
本文转自maclean_007 51CTO博客，原文链接:http://blog.51cto.com/maclean/1277888
