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Cache memory settings for Linux

Posted on 2014-02-13
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Last Modified: 2014-02-25
Hi,

For an application we have a 4 node cluster. The first node 04 was rebuilt recently and we are noticing that it's caching lot of memory by the operating system

compared to the other 3 node. What setting on this machine should I look for to compare with the others

Please see the screen shot below and the machine with name 04 is caching almost 950 GB compared to the others

picture of 4 machines
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Question by:anshuma
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by:anshuma
anshuma earned 0 total points
ID: 39856897
These are 2 TB RAM machines and we don't want to cache so much as the cache scan is taking lot of resources
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by:Mazdajai
Mazdajai earned 166 total points
ID: 39858078
Cached memory often time is a normal behavior. Linux borrows unused memory for disk caching to speed system up. Node04 is also running half of the tasks as the other nodes. What is the baseline before you rebuild the operating system?

You can use vmstat to compare of each server. Try -  

vmstat -S M

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by:Sandy
Sandy earned 167 total points
ID: 39858251
check for /etc/sysctl.conf .. to me it seems like some kernel parameters need tweaking in node4.

TY/SA
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gheist earned 167 total points
ID: 39868713
Try slabtop command
All these parameters influence paging and cache:
https://www.kernel.org/doc/Documentation/sysctl/vm.txt
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by:anshuma
ID: 39885109
thank you very much
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