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Top wait event - control file sequential read [message #432185] Sun, 22 November 2009 17:30 Go to next message
oracleperm
Messages: 2
Registered: November 2009
Location: California
Junior Member
Hi friends,

From AWR reports, the top wait event is "control file sequential read". The control files are located on ASM diskgroup with raid 10 (mirror and stripe). How can I know the ASM disk(s) associated with the control files, and what disks are the hot disks that causing this wait event?

Any advice is greatly appreciated.

Thanks,

Jenny -
Re: Top wait event - control file sequential read [message #432197 is a reply to message #432185] Sun, 22 November 2009 23:19 Go to previous messageGo to next message
Michel Cadot
Messages: 64130
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
Database Reference
Annex C Oracle Wait Events
Section Descriptions of Wait Events
Paragraph control file sequential read

Regards
Michel
Re: Top wait event - control file sequential read [message #436668 is a reply to message #432197] Fri, 25 December 2009 00:58 Go to previous messageGo to next message
kuailingtong
Messages: 4
Registered: September 2009
Junior Member
Reading from the control file. This happens in many cases. For example, while:

Making a backup of the control files

Sharing information (between instances) from the control file

Reading other blocks from the control files

Reading the header block
Re: Top wait event - control file sequential read [message #436700 is a reply to message #432185] Fri, 25 December 2009 21:30 Go to previous message
BlackSwan
Messages: 25042
Registered: January 2009
Location: SoCal
Senior Member
Top wait event
In EVERY Top Wait Event list, one wait event will ALWAYS be on top as #1; by definition of the list.
Simply because any item, even #1, appears on this list does not mean this is a problem & needs to be fixed.
If the Top Wait Event accounts for only 5 seconds out of a 1 hour sample,
then reducing it to ZERO won't measurably improve overall application performance.

The actual Time Waited is required to determine if it is a problem or not.

[Updated on: Fri, 25 December 2009 21:31]

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