In computing, the kernel is the main component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level. The kernel's responsibilities include managing the system's resources (the communication between hardware and software ...

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321 views

Linux cgroups cpuset w/ subs causes cgconfig not to start

I am having a problem trying to separate 2 groups using cpuset subsystem. This works fine, however if i go to add a subgroup to that group (in this case -- user1), cgconfig will fail to start with ...
2
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1answer
109 views

High shmmax value in Redhat 6.3

We are using Redhat 6.3 with 30G RAM to host our Postgres server. The (default) shmmax value is 68,719,476,736 In some forums I have read that having an shmmax value larger than the RAM causes ...
2
votes
1answer
317 views

/proc/<pid>/stat children CPU time

I've been running the following command on my linux box: watch -d -n 1 "cat /proc/19866/stat" The pid above is a pid of Nginx's master process - I would expect the following fields to be changing: ...
1
vote
1answer
335 views

Command apt-get -t wheezy-backports install linux-image-amd64

I have a server with Debian wheezy and kernel vmlinuz-3.2.0-4-amd64, hosted at OVH. I would like to upgrade the kernel. Normally at ovh, you can find some kernel already configured. but the files I ...
1
vote
1answer
152 views

kvm hypervisor kernel panic

My kvm hypervisor had been running with 20+ vps guests for a few months. But a few days ago it went to kernel panic. There were no abnormal operation that I found would cause the problem, except that ...
1
vote
1answer
231 views

backup files to a remote server with multiple versions using rsync hardlink option

To use rsync hard link option to backup files remotely so that remote backup server could keep multiple versions of the backups, both the link-dest directory and the target directory have to be on the ...
1
vote
1answer
162 views

EC2 kernel decision and issues with creating a new machine with my AMI

I could really use some advice. I started a new instance on EC2 using Amazon's AMI and during the deployment process I selected a Kernel ID of "Use Default". I then configured my server the way that ...
1
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1answer
153 views

How to package a custom kernel for Debian?

I've build a custom linux kernel from the vanilla source tree using the deb-pkg target: make deb-pkg After that package has been built I've got several .deb files. However I'd like to upload those ...
1
vote
1answer
475 views

CentOS OpenVZ fail to boot after kernel update

After upgrading to latest OpenVZ kernel CentOS server won't boot. When i try go boot the latest kernel server is stuck at this point: (note that images are taken from virtual kvm) ...
1
vote
1answer
397 views

How can I find the cause of a system hang from the system logs?

I am running a Ubuntu 10.04 LTS in an Amazon EC2 instance. The system suddenly became unresponsive. When I checked the log files I found the following errors in /var/log/syslog Feb 22 04:10:01 ...
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vote
1answer
287 views

OpenVZ with RHEL6 kernel & page cache?

After upgrading kernel from debian 2.6.32-openvz-amd64 to RHEL6 2.6.32-042stab035.1, I have problem with kernel page cache. Looks like no OpenVZ containers use page cache and now I have 10-15GB free ...
1
vote
1answer
458 views

Suggestions needed to debug why ps -ef gets stuck

Issue beginning - Few of my PID consume 100% cpu, I want to understand which script is executing that PID command. My debugging steps: strace ps -ef open("/proc/PID/status", O_RDONLY) = 6 read(6, ...
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0answers
239 views

Monitoring Linux Kernel Space Processing

I'm running two "services" that are served in linux kernel-space: Linux Netfilter Firewall ("iptables") Linux Virtual Server Loadbalancer ("IPVS", "LVS") Now I want to (performance-)monitor my ...
2
votes
0answers
41 views

BUG message on xenserver 6.5 - bad memory?

Several times a day I receive the following error in /var/log/messages. The server hangs and requires a reboot to respond again: Feb 1 13:44:54 xenserver-abfuqvrs kernel: [35023.166776] BUG: unable ...
2
votes
0answers
653 views

OpenVPN ERROR: could not insert 'tun': Unknown symbol in module, or unknown parameter (see dmesg)

I'm trying to configure OpenVPN on my Debian 7 VPN but I'm getting the following error ERROR: could not insert 'tun': Unknown symbol in module, or unknown parameter (see dmesg) I tried the ...
2
votes
0answers
273 views

Ubuntu 14.04 / Apache 2.4 causes kernel fault on Amazon EC2 medium instance

Got a disturbing crash while performing 'apachectl stop'. General system: $ uname -a Linux www.example.com 3.13.0-24-generic #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux ...
2
votes
0answers
147 views

Redhat 6.4 configured to log Martian packets but is not logging ll header

I am trying to investigate the source of martian packets I have been seeing on several servers connected to the same subnet. The logging of martian packets has been enabled in /etc/sysctl.conf. ...
2
votes
0answers
109 views

Upgrading kernel on Debian server hosting Xen 3.2.1

I have a physical server running Debian 6 and Xen Hypervisor 3.2.1, and kernal -a says "2.6.26-1-xen-amd64". I have not updated for a long time, because when I run apt-get upgrade, one of the updates ...
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0answers
44 views

Upgrading CentOS from 6 to 7 has broken my boot sequence

I ran the upgrade assistant provided by CentOS for upgrading from CentOS 6 to 7. The upgrade appeared to have been a success, however my system now hangs when trying to boot up. (Keep in mind I have ...
1
vote
0answers
300 views

OpenVZ - updating kernel and all containers

Last night I upgraded to the latest kernel of openvz. I rebooted the host node. It came up with the latest kernel. However, the containers are still running the old kernel. What I did on the host ...
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0answers
55 views

collect previous kernel logs in linux after reboot

how to collect previous kernel logs in linux after reboot and how to search the old logs? Initially when system is rebooted the logs are not captured and found rest of the log's.But there is an error ...
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0answers
102 views

Linux kernel module “Unknown parameter” stops module from loading. How to load module anyway?

The following is happening on a Ubuntu 10.04 system I'm working on: The kernel is shipped with e1000 driver module version 7.3.21-k5-NAPI. This version of the module is causing problems. To fix, the ...
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0answers
24 views

Process identifier mask in z/OS

I've noticed a curious pattern to process identifier numbers on the z/OS system I'm working on (uname reports it as OS/390), they're either 1-4 digits long or 8 digits long but never in between. The ...
1
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0answers
219 views

demonstrate Automatic Hardware Clock Synchronization By the Kernel (11 minute mode) without ntpd

From the man page of hwclock: This mode (we'll call it "11 minute mode") is off until something turns it on. The ntp daemon xntpd is one thing that turns it on. You can Ok, I have a ...
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0answers
156 views

iptables xt_recent change in kernel without modules

is it possible to change xt_recent module parameters when it is compiled into kernel ? most of the info on internet suggest setting it by modprobe but that is not the case in my setup as I have ...
1
vote
0answers
231 views

FreeBSD XEN kernel not booting in XenServer 6.2

I have a XenServer 6.2 host, and I am trying to get a FreeBSD-9.1-i386 guest to run in PV mode. The installation of the guest is fine, but after a reboot with the new kernel the system does not boot. ...
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0answers
335 views

Xen hangs on boot when scrubbing RAM

I have a CentOS 5 server I can boot into the stock kernel just fine, but when I try kernel-xen, it gets stuck here: http://i.stack.imgur.com/wAI20.png When I try adding no-bootscrub to the kernel ...
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0answers
323 views

CentOS 6 won't load default (new) kernel, loads (another) older one instead

I am having a weird issue with a CentOS 6 system. I have upgraded the kernel twice now and when I reboot the system it still loads the older kernel. I also had a dc tech watch the screen as it ...
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0answers
325 views

UDP socket receive buffer size change on RHEL6.3

Our system used to work on RHEL5.3 And the socket receive buffer size is 64k. And that works fine. We can get message size up to 64k on UDP socket. But after system upgrade, it is running on RHEL6.3 ...
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0answers
694 views

“sched: RT throttling activated” KVM host - what does this mean?

Ubuntu 12.04 64bit - under a KVM parent. 32 cores. So we seem to be having some load issues. We have noticed this line in kern.log: "kernel: sched: RT throttling activated" What does this mean? Is the ...
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vote
0answers
197 views

what does setting kernel.shmall too high do?

I'd like to know what the kernel does when the value of kernel.shmall works out to being larger than the total amount of available memory (main memory + swap space). Is the value ignored and the ...
1
vote
0answers
296 views

Ubuntu - random reboot since 3.0 kernel

I have an Ubuntu Server that is now upgraded to 12.04 LTS server. Ever since I've upgraded from 10.10 to 11.04, when the kernel went from 2.6.38 to 3.0.anything, my machine would constantly randomly ...
1
vote
0answers
174 views

Find counts of ulimit quotas

So, we may have some sort of zainy leak in our software. We're using Mono and spawning many processes over the course of weeks/months. Eventually, we can't spawn anymore on our clients machines. It ...
1
vote
0answers
381 views

Does TIME_WAIT affect dynamic ports?

I've read a bit about TIME_WAIT connections, and know they should be harmless to my server (connection closed, so no resource connected with this socket). Recently, my server reached the magic ...
1
vote
0answers
152 views

Would OOM_Killer succeed if SIGKILL didn't?

Last week an user application turns out to hog one of my servers. It was exhausting the memory gradually and slowly. When I attempted to kill -9 PID the PID went in state D. While this was eating the ...
0
votes
0answers
9 views

Network Interfaces Cards and rx_short_length_errors and Linux Kernel

My machine (Linux OS) is counting packets with wrong length, it is a huge environment (GW's, Routers, Switches...) , so I would like to understand how NIC's behaving with these packets. -Does NIC's ...
0
votes
0answers
23 views

How to find what is causing a Kernel EventTracing error in the Event Log?

I am troubleshooting a Kernel EventTracing: "session failed to start with the following error: 0xc0000011" that pops up too many times in my event log. Every solutions I found in google were very ...
0
votes
0answers
28 views

How does a kernel patch propagate into distribution updates?

I have been affected by, and helped to debug, a kernel bug. A patch has been created by the maintainer of the module, and submitted. I am interested to know how the patch propagates through to binary ...
0
votes
0answers
12 views

EXSI4.0. 2 different kernels - one boots other locks up immediately, how to check initrd difference

I have a ESXI4.0.0 (v4) host, where I am trying to install a guest. The host machine is a regular Intel PC. I have 2 different ISO images (heavily modified version of SLES for a commercial product), ...
0
votes
0answers
103 views

How will updating kernel affect everything else?

I'm new to Linux and I'd like to try to upgrade kernel on my little NAS, but I don't really know how it will affect installed packages and user files, and do I really need to upgrade it? Plus the ...
0
votes
0answers
173 views

Strange memory usage behavior in GlusterFS machines

I'm running into a strange high memory usage problem in my environment. I have a two GlusteFS nodes that are serving 26 replicated volumes. Each morning, both servers will consume the majority of all ...
0
votes
0answers
241 views

Nodes crash with kernel panic due to some bugs in autofs4 module

Recently, my computing nodes started to crash very often. In a pool of ~100 nodes running Ubuntu 12.04 for scientific computing, a machine dies every hour with the following kernel panic message: ...
0
votes
0answers
127 views

Verify architecture of kernel file

Note: I am NOT interested in the currently running kernel, but on a kernel that I am going to boot and which is in a file in the filesystem. I am going to boot a new kernel. I have prepared grub.conf ...
0
votes
0answers
38 views

How do I configure kdump with extra_modules on ubuntu?

I need to configure extra modules to load with kdump (specifically, vga16fb.ko). On RHEL systems it's in /etc/kdump.conf, but ubuntu doesn't have this file. I've looked in /etc/default/kdump-config, ...
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0answers
545 views

Linode Kernel Headers

I am trying to install the Idera (R1soft) linux agent on a Linode running Ubuntu 12.04LTS. The agent requires a driver which in turn requires the kernel headers. Linode uses custom kernels though so ...
0
votes
0answers
186 views

yum update leads kernel error

When I do 'yum update', the following error is shown. Before running the suggested command, I shall better understand, what the cause is. Any advice? --> Finished Dependency Resolution Error: ...
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votes
0answers
541 views

Server crash : “unable to handle kernel paging request”

My fresh new Ubuntu webserver randomly crashes with the following error in the syslog. It doesn't respond anymore and I have to do a hard reboot. It happens almost one time a day. Server kernel is : ...
0
votes
0answers
115 views

Java causing kernel panic

I'm running quite a lot of computations on Ubuntu 12.04 (3.8.0-35-generic), application is written in Java (Oracle 1.7.0_45-b18) on a server which has 12 AMD cores. Typically the computations uses 10 ...
0
votes
0answers
120 views

Why does firehol generate an iptables ACCEPT rule on top?

Firehol generates iptables rules from a convenient configuration file. In my /etc/firehol/firehol.conf I have the following very simple configuration to allow incoming connections on http, https and ...
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votes
0answers
18 views

Cannot start OpenVZ container

When I try to start container I got Starting container... Opening delta /var/lib/vz/private/100/root.hdd/root.hdd Adding delta dev=/dev/ploop15117 img=/var/lib/vz/private/100/root.hdd/root.hdd (rw) ...