Clear the cache memory

[Mousa55]

Hi All,
i Want to know how to clear the RAM Cache memory in HP-UX withot reboot the server
Note: i have rp8420 unix server dividing to 4 partition, ad 11i O.S version

thanks

Thanks & Regards

[Zeev Schultz]

Lets clarify first what is "RAM cache memory".
Buffer cache?

Basically,you can't delete deliberately contents of system memory - it will cause OS to panic.
So I beleive that you mean something else than system memory or buffer cache memory?

[Mousa55]

Hi
yes i want to know how to clear countent of buffer cache memory becuse some application in oracle needed it to this

thanks

[Dennis Handly · Accepted solution]

>I want to know how to clear the RAM Cache memory in HP-UX without reboot the server

You can't. You must reboot to change the kernel parms: dbc_max_pct dbc_min_pct
You can of course let the kernel adjust the memory usage until the next time your reboot.

Here are some threads:
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1177682
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1169524
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1146263
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1120231
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1095627
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1081391
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1059252

[Moderator edit: The above links are no longer valid.]

[Ivan Ferreira]

Maybe you are talking about shared memory. In that case, the ipcrm command can you.

http://schogini.us/wordpress/index.php/2005/11/01/oracle-linux-management/

BTW, I see in your profile "I have assigned points to 81 of 304 responses to my questions."

Please keep asigning points to the answers that you get.

Have a nice day.

[Moderator edit: The above link is no longer valid.]

[Zeev Schultz]

Buffer cache as was said is not online tunable.
Strongly suggest to read "buffer cache tuning" part of this doc:

http://docs.hp.com/en/7779/commonMisconfig.pdf

I'd say try manually setting dbc_max|min_pct as it fits best your application.

[Moderator edit: Removed the broken link. Please refer to https://support.hpe.com/]

[Matti_Kurkela]

Maybe the command "sync" is what you're looking for? (see "man 1m sync")

Note that there should be a process named "syncer" running, unless you've disabled it: it runs the "sync" operation automatically in every 30 seconds.

MK

[Emil Velez]

buffer cache entries get cleared out when you unmount a filesystem. Buffer cache always contains the most recent blocks that were filesystem accessed.

I think what you are discussing is shared memory. IF you are dealing with a 64 bit version of oracle that should not be a problem as long as shmmax is set correctly.

[Dennis Handly]

>Emil: I think what you are discussing is shared memory. IF you are dealing with a 64 bit version of oracle that should not be a problem as long as shmmax is set correctly.

My assumption is that the Oracle documentation mentions shmmax and also says to reduce dbc_max_pct & dbc_min_pct.