OS & Oracle

There are quite a few errors which you perphase meet when you begin to use EM in Windows. Such as: "Agent process exited abnormally during initialization" in system event log, "java.lang.Exception: Exception in sending Request :: null" in OEM Database Control Database Instance home page [...]

1. Introduce
The ASH(Active Session History) is the innovative improvement in 10g.
ASH records the activities of Oracle, sampling per second, if a session is using on CPU or waiting on resource, such as db file sequential read, log file sync, latch etc, then this session is considered to be active, and recorded down in the v$active_session_history [...]