Re: Weird database hanging

The waits for 'block change tracking buffer space' are very high entering into the problem. These are not normal events. One client of mine with a very heavily utilized system using block change tracking has not had a session wait on this even in the past month. Unfortunately this event is not documented in the Reference Manual, but we could conjecture (sorry Alex) that it caused by unresponsive I/O wherever the BCT file is. After these linger for a while, we start so see serious waits on a variety of other stuff (SQ eneueue, shared pool latch, cursor pin). There is nothing in Metalink on 'block change tracking buffer space'.
I would seek confirmation from Oracle on the meaning of this event, but in the mean time, I would try to find out if there was a problem with the storage where the block change tracking file is located. 

Jeremiah Wilton
ORA-600 Consulting
http://www.ora-600.net

Don Seiler wrote:

I ran a similar query to give all sums by event and minute from 11:15
to 11:45 (the alert log items first popped up at 11:23).

http://pastebin.com/m426111d8

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