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Oracle 11g high memory usage dbw0 and dbw1 [message #562317] Tue, 31 July 2012 05:21 Go to next message
preet_kumar
Messages: 204
Registered: March 2007
Senior Member
We are using the 11g AMM feature and Memory_Target set to 96GB and total RAM on the Server is 128GB
Now the top and free shows up only 200MB memory free on the system.

There are 2 process dbw0 and dbw1 which consumes the top memory and this is 30GB per dbw.
Why is the dbw process taking up so much memory when there is not much load on the database.

Thanks
Preet
Re: Oracle 11g high memory usage dbw0 and dbw1 [message #562321 is a reply to message #562317] Tue, 31 July 2012 05:33 Go to previous messageGo to next message
Michel Cadot
Messages: 66934
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
Show us: copy and paste what you did and got.
I bet it does not use this memory just point to it.

Regards
Michel
Re: Oracle 11g high memory usage dbw0 and dbw1 [message #562323 is a reply to message #562321] Tue, 31 July 2012 05:45 Go to previous messageGo to next message
preet_kumar
Messages: 204
Registered: March 2007
Senior Member
Below given the copy paste from a test system which is having total 32GB RAM with same problem

TOP
Mem:  32868276k total, 32512932k used,   355344k free,   612780k buffers
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 4123 oracle    20   0 9871m 5.2g 5.2g S  0.0 16.7   3:48.30 oracle
 4121 oracle    20   0 9871m 5.0g 5.0g S  0.0 16.0   3:42.17 oracle

Free
total       used       free     shared    buffers     cached
Mem:      32868276   32526976     341300          0     612796   29244004
-/+ buffers/cache:    2670176   30198100
Swap:     33638392      19596   33618796

$ps -ef|grep 4123
00:03:48 ora_dbw1_11g

$ps -ef|grep 4121
00:03:42 ora_dbw0_11g


[Edit MC: add code tags and align columns]

[Updated on: Tue, 31 July 2012 06:03] by Moderator

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Re: Oracle 11g high memory usage dbw0 and dbw1 [message #562327 is a reply to message #562323] Tue, 31 July 2012 06:06 Go to previous messageGo to next message
Michel Cadot
Messages: 66934
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
The used memory showed here include the shared memory.

Please read OraFAQ Forum Guide and How to use [code] tags and make your code easier to read.
Make sure that lines of code do not exceed 80 characters when you format.
Indent the code, use code tags and align the columns in result.
Use the "Preview Message" button to verify.

Regards
Michel
Re: Oracle 11g high memory usage dbw0 and dbw1 [message #562339 is a reply to message #562317] Tue, 31 July 2012 07:20 Go to previous message
John Watson
Messages: 8201
Registered: January 2010
Location: Global Village
Senior Member
Linux will never have much free memory. This is a Good Thing. Any RAM that isn't needed for active processes will eventually be used for caching. .
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