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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140 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 ...
2
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1answer
109 views

How to tell which device in /dev a kernel module added?

I have just compiled the QLogic qla2xxx FC driver on a CentOS6.4 host, and done echo 'alias scsi_hostadapter qla2xxx' >> /etc/modprobe.d/modprobe.conf cd /boot cp initramfs-$(uname -r).img ...
0
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1answer
335 views

Server hangs after typing reboot command

I have a Debian Wheezy installation with Xen in kernel. All is fine but ... when I type a reboot command or shutdown -r now, my server is stuck and I see only that info on screen: INFO: task ...
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2answers
811 views

Optimal kernel configuration and patches for KVM host

I have a server (single socket Nehalem w/ 24GB RAM) acting primarily as a KVM host containing a bunch of Windows Servers and a few (tickless) Linux instances. I usually compile my desktop kernels ...
3
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1answer
656 views

What does nf_conntrack.acct really do?

I've found the kernel parameter nf_conntrack.acct interesting, in that the kernel documentation merely says "Enable connection tracking flow accounting". I've appended this to grub and rebooted and I ...
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0answers
251 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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2answers
599 views

Why “lsmod | wc -l” not equal “ls /sys/module | wc -l”

Why do these two commands return different results? lsmod | wc -l 100 ls /sys/module | wc -l 138
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1answer
5k views

Unexpectedly shrunk window

I run a major media upload/download site and I noticed these: Is this serious or background noise due to the big file sizes and is there any tweaks I can add to /etc/sysctl.conf to improve and ...
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1answer
436 views

What is the purpose of /proc/config.gz

Please what is the purpose of the /proc/config.gz file in my Linux server filesystem? Is it some backup file, or it is an updated file by the Linux system? Can I change it?
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3answers
762 views

High CPU usage in random IP/Port UDP DDoS

I have been getting these UDP floods with random IPs and ports. randomip:randomport -> myip:randomport 0 byte payload For some reason it is using a lot of CPU. Here is the results of perf top -e ...
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1answer
613 views

What kernel module to compile for getting QOS service on Linux

We are developing on Linux system whose kernel had been compiled without QOS service years ago. Currently we want the QOS service back and plan to compile only the QOS-related kernel modules and ...
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1answer
469 views

Linux kernel option to force video card to stay on

I just installed Debian Wheezy 7.1.0 on an Intel vPro System (Intel Core i5-2520M, SuperMicro MBD-X9SCV-Q-O). Intel AMT's KVM works perfectly until Debian has completed booting and shows the login ...
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0answers
189 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. ...
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1answer
130 views

Xen: what are domU kernel config requirements for live migration?

We recently added iSCSI storage to two Xen servers running a mix of Gentoo and Ubuntu 10.04 and 12.04 domUs. When trying out live migration of domU I found that I can migrate just fine the Ubuntu ones ...
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2answers
239 views

continous kernel EIP errors

I am getting the following error time to time. Process is different at each time. What do you think about the error? What do you suggest? Kernel is Linux version 3.5.3 (developer@devel) (gcc ...
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1answer
176 views

Slackware 10.1 hangs at boot with kernel 3.x

In Slackware 10.1, what happens between rc.S and rc.M during boot? Trying to boot kernel 3.x (tried 3.4 and 3.10) on this box and it hangs right after rc.S finishes execution. 2.6 kernels boot up just ...
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1answer
55 views

forcing linux kernel 3 to recognize cdrom as hdX

I have a problem with older version of anaconda linux installer. I have upgraded kernel in my distro, however, when this anaconda boot with this 3.4.52 kernel, can NOT find cdrom. As far as I ...
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2answers
500 views

Moving a process to and from swap [closed]

I've got serveral processes (game servers) on my linux server that use up 50MB of RAM. They are not constantly being used, and I'd like to be able to run more instances than my RAM capacity allows. I ...
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2answers
1k views

What is using the RAM on this Ubuntu 12.04.2 server?

I have two servers in a pool with Nginx, PHP5-FPM and Memcached. For some reason, the first server in the pool seems to inexplicably lose about 2GB of RAM. I can't explain where it's going. A reboot ...
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1answer
703 views

Ubuntu 12.04 - Grub1 won't load new kernel

For some reason I can't get grub to load the new kernel. I tried removing the old kernels with aptitude and running update-grub but it still loads the old kernel - even though I've removed it! I ...
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1answer
1k views

Kernel parameters mem and dom0_mem in XenServer 6.1

We are running XenServer 6.1 in production, and recently had OOM-killer fire and eventually take down one of our blades. I noticed that in the kernel logs from the oom-killer instance that it seemed ...
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4answers
119 views

Can 3.2 kernel KVM VMs run in a 2.6 kernel host

So I got a Redhat6.2 and going to install it on a new IBM x3650 m4 server. However I want use Debian because I'm more familier with it. Since x3650 doesn't support Debian(I've tried but no luck), I ...
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1answer
1k views

Error setting capabilities, capability management disabled;

root@monitor:/opt/observium# service syslog-ng restart Stopping system logging: syslog-ng. Starting system logging: syslog-ngsyslog-ng: Error setting capabilities, capability management disabled; ...
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2answers
3k views

Disable ICMP Unreachable replies

I am using a Debian 6 - 64bit OS and my server is ddosed/flooded through udp protocol from time to time. I basically host game-servers and my firewall is set to rate-limit the packets on allowed ports ...
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2answers
125 views

How do I make OOM Killer more passive

I am able to compile a program with 1 GiB RAM on a VPS using old 2.6.x kernel. But when I tried to compile it on a VPS with 1.1 GiB RAM and 3.9.x kernel, the compiler always killed by OOM Killer. How ...
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1answer
409 views

Where to find source of an Amazon EC2 compatible kernel

I have some issues with finding the source code of Amazon EC2 compatible kernels. There is a tutorial in Amazon EC2 documentation of how to run instances with custom kernels, but those must be from ...
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4answers
156 views

If kernel type (64/32) is no indication of what bit your distribution is, how do I know what I'm running?

If kernel type (64/32) is no indication of what bit your distribution is, how do I know what I'm running? I'm on Ubuntu, and I just found out, to my surprise, you can use a 64 bit kernel on a 32 bit ...
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1answer
142 views

Pass kernel boot parameters from dhcpd.conf for a host group?

Is it possible to configure dhcpd.conf such that a specific host group would use an additional kernel boot parameter passed on to the kernel loading? Thanks!
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1answer
75 views

Enable CONFIG_VM_EVENT_COUNTERS without reboot/recompile

I have an Ubuntu 12.04 server that I am troubleshooting, and I would like to use iotop. However, it seems that 12.04 doesn't have CONFIG_VM_EVENT_COUNTERS enabled by default (required by iotop). I ...
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1answer
6k views

Testifying rasing net.core.somaxconn can make a difference

I got into an argument on the net.core.somaxconn parameter: I was told that it will not make any difference if we change the default 128. I believed this might be enough proof: "If the backlog ...
3
votes
1answer
131 views

IPSEC AES key length in kernel 3.9.3

I have a working ipsec-tools configuration which uses aes-ctr encryption with 224-bit key (192bit for key+32bit for nonce). Everything works well on 3.2.0 kernel. Here's what man setkey says about ...
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2answers
1k views

Can't build RocketRaid rr268x on Ubuntu 13.04

I am trying to build the kernel module for Ubuntu 13.04 but not having any luck, I have had this card working perfectly fine with 12.10 and the 3.5.0-27-generic kernel but since upgrading to 13.04 ...
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1answer
279 views

Proxmox 3.0 installation on any VPS

I have an account on digitialocean.com I create a droplet debian wheezy. I installed proxmox 3.0 manually via command line. At the end of installation I restarted the server but again it uses default ...
2
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1answer
1k views

Kernel oops on Linux running in VirtualBox breaks some IO-related functionality on the server

We are having problems with CentOS release 6.3 running in VirtualBox on Windows 7 machines. The symptoms are the following: Everything works as normal for several hours, even days. Then something ...
2
votes
2answers
162 views

How to get a kernel panic count [closed]

Is there any way to check the number of kernel panic that happened on a system ? If not, any idea on how to do make this new functionality ? I would like to hear about an answer for most Unix-like ...
2
votes
1answer
2k views

What does this kernel error mean and how should I respond?

The following except is taken from the logwatch of a production LAMP web server I'm about to inherit. It is a dedicated Dell server running CentOS 5 with RAID 1 across two 1TB drives. I have little ...
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votes
3answers
563 views

Enable SMP on Debian i386?

I've been running a couple old HP machines on Debian for a while, and only recently noticed that they were only 'recognizing' and using one processor. cat /proc/cpuinfo only shows output for processor ...
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1answer
168 views

Fuse module for s3fs

I am trying to install the s3fs software. I however keep coming upon this error: $ sudo /usr/bin/s3fs bucketname /mnt fuse: device not found, try 'modprobe fuse' first $ modprobe fuse FATAL: Module ...
0
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1answer
202 views

Wndows Azure: “Linux Integration Services for Hyper-V has been removed.”

When I am trying to yum update my centos in Windows Azure, the following appeared Linux Integration Services for Hyper-V has been removed. Please reboot your system. So I reboot it. But ...
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1answer
66 views

How to update/maintain a patched kernel?

If I patch my linux kernel with grsecurity, will I still be able to update my system with yum (or apt-get)? Won't the updates available via yum be incompatible with my patched "non standard" version ...
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2answers
557 views

fix kernel on Xen Server hypervisor vps

I have a cloud server hosted at Rackspace, and they use Xen Server hypervisor. I was running Ubuntu 12.04, and really messed up by attempting to do a release upgrade manually. The hypervisor ...
2
votes
1answer
123 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 ...
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1answer
102 views

Multiple ethernet interface on one ethernet card

First I must say that I am new in linux and maybe I will ask trivial question. My job is to create 8 ethernet interface to be visible in kernel, but all of them should send and receive data through ...
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0answers
394 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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1answer
989 views

How can I diagnose and fix frequent 100% cpu utilization from kernel?

I have an Amazon EC2 micro instance running an old 2.6.16 kernel. It runs postfix, apache, and mysql. During normal loads, it's load average is around 0.05, and it runs this way 95% of the time or so. ...
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1answer
1k views

RHEL 6.0 upgrading kernel from 2.6.32-71.el6.x86_64 to 2.6.32-358.2.1.el6.x86_64

[root@localhost ~]# rpm -ivh kernel-2.6.32-358.2.1.el6.x86_64.rpm error: Failed dependencies: bfa-firmware < 3.0.3.1 conflicts with kernel-2.6.32-358.2.1.el6.x86_64 [root@localhost ~]# rpm ...
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2answers
397 views

“Never take kernel updates” — Any truth to this?

So I am having a discussion with a coworker today, and he let something out that I thought was bizarre, as I'm getting ready to apply security updates to one of our production servers. "You should ...
2
votes
2answers
3k views

Kernel 3.8, Apache2 with WSGI : INFO: task apache2 blocked for more than 120 seconds

We have upgraded our Kernel from 2.6.32 to 3.8.7 on a Debian system. We have a sharing with NFS to get the data for Apache2. And Nginx serves only static files as a proxy. Since we have installed the ...
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2answers
299 views

Check my Kernel for SELinux Support

I want to know if the kernel i am running has support for SELinux. What commands would i use to check this ?
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1answer
745 views

Adaptec RAID array was not detected after updating the kernel?

Continue from this topic, the newer kernel booted successfully but it doesn't see my sdc - which is a hardware RAID array (level 10). I'm sure the aacraid module is loaded: # grep aacraid ...