CentOS 6.4 Core files

Posted on 2013-06-30
Last Modified: 2013-07-03

I have installed CentOS 6.4 64bit few days ago and noticed that the hard drive got full within few days. I looked in /tmp folder and noticed lots of core.numbers files ie core.1111 core.32323

These files are being created every few seconds.

ulimit -c shows zero which basically means that no core file should be created.

I would like to know why these files are being created? Apparently I need to know the application that is creating this file before debugging.

And how do I stop these files from being created?

Question by:ezzadin
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Expert Comment

by:Kerem ERSOY
ID: 39288726

Will you post your dmsesg output here?


Author Comment

ID: 39288775

Attached is the dmesg.

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Expert Comment

by:Kerem ERSOY
ID: 39288784
I did not find anything unusual here. Will you please post :


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Expert Comment

by:Kerem ERSOY
ID: 39288785
It seems that your system was configured to generate core dump files for crashes. I think we need to find what is causing crashes.
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Author Comment

ID: 39288812

here is sysctl:

# Kernel sysctl configuration file for Red Hat Linux
# For binary values, 0 is disabled, 1 is enabled.  See sysctl(8) and
# sysctl.conf(5) for more details.

# Controls IP packet forwarding
net.ipv4.ip_forward = 0

# Controls source route verification
net.ipv4.conf.default.rp_filter = 1

# Do not accept source routing
net.ipv4.conf.default.accept_source_route = 0

# Controls the System Request debugging functionality of the kernel
kernel.sysrq = 0

# Controls whether core dumps will append the PID to the core filename.
# Useful for debugging multi-threaded applications.
kernel.core_uses_pid = 1

# Controls the use of TCP syncookies
net.ipv4.tcp_syncookies = 1

# Disable netfilter on bridges.
net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0

# Controls the default maxmimum size of a mesage queue
kernel.msgmnb = 65536

# Controls the maximum size of a message, in bytes
kernel.msgmax = 65536

# Controls the maximum shared segment size, in bytes
kernel.shmmax = 68719476736

# Controls the maximum number of shared memory segments, in pages
kernel.shmall = 4294967296

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I didnt see anything is /var/log/messages.

I rebooted the system few minutes ago and it stopped creating the files...
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Accepted Solution

Kerem ERSOY earned 500 total points
ID: 39289292
In fact you don't have a core file setting in your sysctl file. For your system to create dump files like that you had something different in your sysctl. Something like this:

kernel.core_uses_pid = 1
kernel.core_pattern = /tmp/core-%e-%s-%u-%g-%p-%t
fs.suid_dumpable = 2

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But you don't.

There's one thing that comes to my mind that may be you have booted from a different kernel from CD or something which had these settings..

Is it possible that you've reboot from rescue kernel and set your your after boot ??

This is the only thing that I could come up with..


Author Comment

ID: 39290027
I actually had this box installed and configured in the office and had is running for few days then shut it down and moved it to our data-center and powered up.

The system started creating the dump file when it was powered up in the data-center, so as you mentioned maybe it just booted from rescue kernel and once the server was rebooted, it started normally.

In any case, thanks for your help.
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Expert Comment

by:Kerem ERSOY
ID: 39298354
You're welcome.

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