RE: standby config --> FAL_SERVER / FAL_CLIENT
- From: <k.sriramkumar@xxxxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 11 Feb 2004 10:07:08 +0530
Hi Jonathan,
Thanks for highlighting the same. I have one question on this and hope =
you would help me out. This factor of three as I understand is that if a =
normal commit takes a factor time/wait? Pls explain) of x then maximum =
protection mode would be a factor of 3x.=20
Also this 3x factor is for a single standby instance and would increase =
3x times for every additional setup of standby databases. Is my =
understanding correct?
Best Regards
Sriram Kumar
-----Original Message-----
From: Jonathan Lewis [mailto:jonathan@xxxxxxxxxxxxxxxxxx]=20
Sent: Wednesday, February 11, 2004 1:45 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: standby config --> FAL_SERVER / FAL_CLIENT
Just clearing up a point on Maximum Protection
and the meaning of "(does not wait till its applied)".
Isn't this the option where lgwr has to wait for
confirmation that the redo has been written=20
into the standby log on the standby database=20
before writing to the online log on the primary=20
and acknowledging the commit.
One thing to watch out for with standby and
this option is the effect on commits within=20
pl/sql calls. Oracle does not wait for sync
if you issue a commit inside a pl/sql call,=20
issuing only one log sync write at the end=20
of the call - but if you switch to maximum protection,
then every commit inside the call becomes a
log sync call, and performance get much
worse. (I've had one report of a factor of
three for a piece of code doing lots of commits
inside a pl/sql loop).
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
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who can answer the questions, but the=20
person who can question the answers -- T. Schick Jr
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----- Original Message -----=20
From: <k.sriramkumar@xxxxxxxxxxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Tuesday, February 10, 2004 12:15 PM
Subject: RE: standby config --> FAL_SERVER / FAL_CLIENT
Hi Prem,
Yes there is a performance overhead with maximize protection. As I said =
=3D
earlier, the LGWR process is going to ship the log changes to the =3D
standby database (does not wait till its applied) and hence It boils =3D
down to the network connectivity that exists between the primary and the =
=3D
standby database. Your overhead is proportional to the network =3D
bandwidth. Pls test it with a real load before you put in production.
Best Regards
Sriram Kumar
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