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LOG_BUFFER maximum size

Sreesankar GMApr 16 2015 — edited Apr 20 2015

Hi Guys,

I've got a question regarding LOG_BUFFER initialization parameter. What is the maximum size allowed for this value? I got from some online forums that high values doesn't benefit much, but there is no harm in increasing it. What I have is a very huge table to update - which I'm chunking using DIY parallelism (from Tom Kyte) and executing 5-6 chunks at a time. During the execution, most wait event reported is on 'log buffer space' event. As I understand, it is either due to slow log disks or improper log_buffer tuning. Before going into disk speeds, I would like to get clarity on LOG_BUFFER.

Now, I tried increasing the value, but whatever value I give in init.ora file, the 'show parameter log_buffer' doesn't go above 268427264 (I think that is almost 256MB). I have tried giving 2GB in the init.ora file but this doesn't go above 256MB. How is this upper limit calculated by Oracle? And how can I increase it?

Could you please help?

Oracle version: 11.2.0.3.0

OS: IBM AIX 7.1

Number of cores: 4 ; Number of VCPU : 4 ; So, that gives 16 CPUs

RAM: 40GB

SGA_MAX_SIZE: 15G

SGA_TARGET: 0

PGA_TARGET: 1G

If you need any more info, please do let me know.

This post has been answered by John Stegeman on Apr 16 2015
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