[CentOS] CentOS 3 vs. CentOS 4 Memory Utilization

Sat Feb 10 16:27:59 UTC 2007
Fred Kienker <fred at at4b.com>

-----Original Message-----
From: centos-bounces at centos.org [mailto:centos-bounces at centos.org]On
Behalf Of William Warren
Sent: Saturday, February 10, 2007 11:19 AM
To: CentOS mailing list
Subject: Re: [CentOS] CentOS 3 vs. CentOS 4 Memory Utilization


yes i did.  The 2.4x Rh kernels actually aren't right in their swapping 
behavior.  it really nailed my samba server here at the house and caused 
massive swapping and load issues on a friend's gaming server.  i don't 
know what it is about RH's 2.4x kernels but they swap and won't give the 
cache memory back.  I have more than 6 ipcop firewalls based on 2.4 
kernels(not RH) and they won't swap unless you actually exhaust physical 
memory.  The issue is the RH 2.4x kernels which for some reason continue 
to swap even with 500 MEGS of cache memory available to take back.  2.6x 
runs much better and actually obeys the swappiness commands.  Even the 
various patches done by Rh on the 2.4x kernel never reduces this behavior.

Les Mikesell wrote:
> William Warren wrote:
>> i moved away from Red Hat 2.4x kernels as they have an annoying 
>> tendency to swap instead of giving back cache.  I moved to Centos-4 
>> and i have vm.swappiness to zero and am using at most 144K of swap 
>> across 5 machines.
> 
> Did you see any real-world improvement from this?  The kernel may be 
> right in swapping out little-used parts of memory to release RAM for 
> something more likely to be active.
> 

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_______________________________________________


I HAVE to agree with this assessment. We tried everything issued from RedHat, patches, new kernels, and new
settings, and could never get this under control. Since we had no software tied to Version 3 we 
finally gave up and migrated all of our systems to Version 4. There have been no problems like
those we had with Ver. 3 since.

============================================ 
Fred Kienker 
AT4B 
5261 Sunset Trail 
Marietta, GA 30068 

Fred at at4b.com 
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