RE: "wait for scn from all nodes" wait in RAC
- From: "Hameed, Amir" <Amir.Hameed@xxxxxxxxx>
- To: <Cary.Millsap@xxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Sat, 16 Jul 2005 13:05:35 -0400
Cary,
Based upon the explanation of this event, it seems like a legitimate
concern. As for whether this event was a dominant contributor to the
response time of an important business task, the answer is, I don't know
at this point and I will have to isolate this by looking at waits at
various time intervals and then see what ran during that time to narrow
it down. But, it seems that this issue is not really dependent on a
business event; it is the time it is taking for the roundtrip for the
confirmation of the SCN so that the LGWR can write the redo. We are
using three private gigabit interconnects and in theory there is enough
bandwidth available to the IC path.
Amir
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Cary Millsap
Sent: Friday, July 15, 2005 4:47 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: "wait for scn from all nodes" wait in RAC
Amir,
Only you can tell us whether the issue is of legitimate concern,
right? :-)
Is the event a dominant contributor to the response time of an
important business task?
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
Nullius in verba
Visit www.hotsos.com for curriculum and schedule details...
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Hameed, Amir
Sent: Friday, July 15, 2005 3:14 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: "wait for scn from all nodes" wait in RAC
Does anyone know what this wait (wait for scn from all nodes) is
about in RAC. We are currently running a test on a two-node RAC/11i
instance. Statspack is showing this wait among the top five (at #5). We
are using the "broadcast on commit" scheme as it is recommended by
Oracle for 11i instances. Per Metalink, this event is related to the
broadcast scheme that we are using. But what does it really mean and at
what point it becomes a matter of concern? Any feedback will be
appreciated.
Thank you
Amir
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