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Re: swapinfo -tam HIGH (dbc_max_pct=50)

 
Akif_1
Super Advisor

swapinfo -tam HIGH (dbc_max_pct=50)

Hi,

OS:HPUX 11.11
Oracle Application 9.0.4
Problem:Memory usage high
RAM 8GB

My memory usage is very high 94% and i need an expert advice upon this issue,

#If i make changes to configurable parameter "dbc_max_pct" which is 50 now does this effect my Oracle Application Server 9.0.4 production environment.

#In case need to revert back old setting what backup to be taken and how to revert it back.

Note: Find an attach file which highlight top/swapinfo/iostat/vmstat info.

Have a good day to all........

Regard's
T(ogether) E(very one) A(chive) M(ore)
27 REPLIES 27
SoorajCleris
Honored Contributor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

Hi ,

you 80 % swap is already used, it shows that you have pageouts and there must be a memory crunch.

Before reducing the dbc_max_pct, you can check the usage of the parameter.

Do you have glance installed ?

if yes , check what is the current usage for buffercache.

What is the current buffer cache read write hit ratio, is that utilized?


when it was noticed for first time?

Is there any io issue , disk issue,


If you have kmeminfo, it will tell you where the memory is used (but log a case with HP if you have support )

Regards,
Sooraj
"UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity" - Dennis Ritchie
SoorajCleris
Honored Contributor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

### sorry 18% swap
"UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity" - Dennis Ritchie
Raj Briden
Frequent Advisor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

This problem is usually caused by the new dbc_min_pct and
dbc_max_pct kernel parameters. Your dbc_max_pct was probably
set at the default value of 50%, so it is consuming half of
your RAM over time, thus slowing performance and using memory.
SoorajCleris
Honored Contributor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

#In case need to revert back old setting what backup to be taken and how to revert it back. ==>


dynamic kernal parameter deosnt require reboot to take effext.

Regards,
Sooraj
"UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity" - Dennis Ritchie
Akif_1
Super Advisor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

Iam unable to get ouput from #glance command, My worried area is Oracle Application Server,when i make any changes to dbc_max_pct.

Regard's
T(ogether) E(very one) A(chive) M(ore)
Dennis Handly
Acclaimed Contributor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

>If i make changes to configurable parameter "dbc_max_pct" which is 50 now does this effect my Oracle Application Server 9.0.4 production environment.

Hopefully you'll be able to use more of RAM for your Oracle database. 50% is just too high.

>In case need to revert back old setting what backup to be taken and how to revert it back.

There will be no need to change it back. But you just do the same thing and change it to 50.

>Sooraj: dynamic kernel parameter doesn't require reboot to take effect.

This is 11.11, I don't think they are dynamic.
Akif_1
Super Advisor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

Hello Dennis,

I appreciate your response to my query, I will go ahead with the dbc_max_pct=20 of 8GB.

Hope while rebooting it will not effect any process.

does a /stand/vmunix backup is a safety to revert back incase of any failure.

Why i am more concern is that , this is a prodution server and it is building new kernel while making changes to dbc_max_pct.

Regard's
T(ogether) E(very one) A(chive) M(ore)
SoorajCleris
Honored Contributor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

Hi Dennis,

I was in a doubt ( so I put a common sentence :) ). I know in 11.23 its immediate. But I couldnt loggin 11.11 and check.

Thanks :)
"UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity" - Dennis Ritchie
SoorajCleris
Honored Contributor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

Yes,

booting from previous kernel will give you old settings.

1. It is recommended to take latest ignite before you make any changes.

2. Its always better to take a reboot before making any changes to ensure the server is booting fine currently. This will help you to isolate if any issues after the change.

Regards,
Sooraj
"UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity" - Dennis Ritchie