Spotlight on Oracle 11.0 - Getting Started Guide

Cell Balance Alarm (Exadata)

The Cell Balance alarm is raised when there is an unequal distribution of work-load between the Exadata Storage Servers (Cells).

The source of this alarm could be:

• A new Exadata Storage Server (Cell) has been added, or an existing Cell has been restarted.
• An Exadata Storage Server (Cell) has failed.
• Services have failed on an Exadata Storage Server (Cell).

Actions to take:

• Rectify any hardware problems.
• Check the management services on the Exadata Storage Servers (Cells).

The balance metric is based on total reads and writes for each cell. To determine whether there is an unequal distribution of work-load the Kruskal-Wallis Non Parametric test (to a 95% probability) is applied to the 30 most recent historical values. For installations where there are two Exadata Storage Servers the Mann-Whitney U test is used.