Sessions wait on this event in Exadata when creating tablespaces, adding files to an existing tablespace or automatic expansion a data file because of DML operations, e.g. data is being loaded into a table. One of the performance gains of Exadata when creating of modifying files is that activity is offloaded to the storage cells rather than performed by the database server. This can make the process much faster and less impactful to the database server. To make sure this option is enabled by default, check the parameter "_cell_fast_file_create"=TRUE. Solutions This event should not be a major contributor to wait times. If there are excessive waits on this event, it indicates that file creation or extension is taking a long time or being done too often. Check the code that is creating datafiles and ensure file sizes and numbers of files are appropriate. If this is related to DML activity, check the autogrowth options on the tablespace to make sure it is sized large enough to prevent many small extensions.
本文转自maclean_007 51CTO博客，原文链接:http://blog.51cto.com/maclean/1277893
