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 ...
0
votes
0answers
201 views
Atop shows problems with paging frequency
I have a debian server and when running "atop 1" the "PAG" row is nearly always red which shows an issue with the paging frequency. Here is an example
PAG | scan 10477 | stall 0 | ...
0
votes
0answers
84 views
FreeBSD - memory gap
I came across script that prints some memory informations and here is my output:
SYSTEM MEMORY INFORMATION:
mem_wire: 4133535744 ( 3942MB) [ 12%] Wired: disabled for paging out
mem_active: ...
0
votes
1answer
198 views
How to use Linux 3.3 BQL (Byte Queue Limits)? [closed]
How do I take advantage of the BQL (Byte Queue Limits) in Linux 3.3?
Do I just install the kernel?
Does it help with UDP traffic?
0
votes
1answer
208 views
net_device get_stats function, how to use? [closed]
I'm trying to write a linux kernel module to get stats from my NIC, I learned that a struct called net_device has a function called get_stats that returns a struct with a lot of statistics that I need ...
0
votes
0answers
352 views
Ubuntu 10.04 Server w/ root on LVM2, Cannot boot after kernel update
I am running an Ubuntu 10.04 Server with root on a md raid 5 / LVM2 volume. After a kernel update, boot hangs at initramfs saying it gave up waiting for root, "ALERT! /dev/disk/by-uuid/##..## does ...
8
votes
2answers
532 views
Linux Kernel Versioning: Debian Sid vs Ubuntu Precise
I have setup two machines:
On one machine I have installed Ubuntu Precise 12.04 beta and dist-upgraded to the latest packages.
On the other machine I have installed Debian Sid Unstable and ...
5
votes
2answers
2k views
Converting an EC2 AMI to vmdk image
I've come quite close to getting Amazon Linux to boot inside VirtualBox, thanks to this answer and these websites. A quick overview of the steps I've taken:
Launch EC2 instance with Amazon Linux ...
1
vote
1answer
268 views
Redhat Kernel patching advice
An audit has pointed out that a RHEL server I manage has not had the latest kernel patches applied. I'm confused about kernel patching and within RHEL in relation to RHEL dot releases i.e 5.2 , 5.3 ...
2
votes
1answer
1k views
Sporadic unspecific kernel panic
I'm experiencing seldom (so far about once a month) hard crashes on our ubuntu server 10.04 LTS box. The box itself is quite old (Dell PowerEdge 750 from 2004, Pentium4 2.8 GHz). I set up netconsole ...
3
votes
3answers
9k views
How to set shmall, shmmax, shmni, etc … in general and for postgresql
I've used the documentation from PostgreSQL to set it for example this config:
>>> cat /proc/meminfo
MemTotal: 16345480 kB
MemFree: 1770128 kB
Buffers: 382184 kB
...
2
votes
1answer
654 views
Build kernel headers to compile R1Soft hcp module
I'm running a Xen based VM with CentOS 5, and my hosting provider pushes kernel version 2.6.37.6 from the host machine (so no pv-grub).
[root@dev ~]# uname -r
2.6.37.6
I'm trying to install the ...
0
votes
1answer
192 views
ASUS PIKE 6480 doesn't work with debian?
I have DIYed an 1U server with [ASUS Z8NA-D6] motherboard, PIKE 6480
extended RAID card, and four SAS hard disk. And I can find this extended card's module in the linux kernel called mvsas. But fail ...
1
vote
2answers
386 views
New kernel compilation on CentOS
I'm trying to compile and install kernel 3.2.9 for CentOS 5.6.
I compiled new kernel and installed kernel modules:
make && make modules_install
I also created new initrd image:
mkinitrd ...
2
votes
1answer
610 views
Under what circumstances will Linux ignore the route table when choosing the MAC address for an outbound frame?
While debugging a problem with the networking configuration for a set of virtual machines running under KVM, I discovered a circumstance where the kernel in the guest VM has decided to stamp the ...
1
vote
1answer
48 views
Linux group keyring (eg request_key and add_key)
I'm working on building an application that needs to use the group keyring to share some sensitive data between processes with different owners. Whenever I try to access the group keyring (e.g."@g") ...
0
votes
2answers
735 views
Kernel update without reboot [duplicate]
Possible Duplicate:
Reloading a kernel “live” in CentOS / RHEL 6
How can i update kernel on Centos without reboot .?
I found ksplice but it is not supported for Centos.
...
0
votes
1answer
384 views
How to start compiling Linux in a KVM virtual machine?
I want to learn more about the Linux kernel, which means I want to start compiling and testing my own kernel. I'm running Ubuntu 10.04 on my box, so I'll be using QEMU/KVM for virtualization.
I was ...
0
votes
1answer
272 views
Yum freezes on Running Transaction Check
Strace: http://pastebin.com/r8D39yLg Kernel:
2.6.18-274.12.1.el5.centos.plus #1 SMP Tue Nov 29 18:16:47 EST 2011 x86_64 x86_64 x86_64
GNU/Linux System: CentOS 5.7 64-bit
How to fix this ?
2
votes
1answer
722 views
Finding out TCP Initial Window segment size in linux
I run Centos
[user ~]$ cat /etc/redhat-release
CentOS release 6.2 (Final)
With kernel
3.0.4-x86_64-linode21
How do I check the TCP initial window size in my OS? I need to verify that the IW is ...
0
votes
1answer
503 views
iptables DNAT from loopback
I'm trying to understand the limitations of using iptables DNAT with loopback addresses. Consider we have an application which can connect only to 127.0.0.1; the obvious solution to make server and ...
1
vote
1answer
203 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
248 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 ...
0
votes
1answer
314 views
yum install kernel source
I'm installing dahdi on my Fedora 15 machine and when I try to build, I receive the following error
You do not appear to have the sources for the 2.6.38.6-27.fc15.x86_64 kernel installed.
The ...
0
votes
3answers
4k views
How long does it take to fsck a volume?
We are running website which is currently serving 3-5 million page views. Our site is file sharing site and so it contains 250,000 files and few thousand symbolic links.
The hard disk is a 1500GB ...
0
votes
0answers
226 views
xen domU kernel panic with “alignment check” on 2.6.32-5-xen-amd64
I'm running 2.6.32-5-xen-amd64 on a domU with Debian stable and 6 vcpus. Without changing anything in the architecture 3 days ago it started throwing kernel panics on high load. I've researched online ...
1
vote
2answers
232 views
Changing VPS provider, kernels changed…broke my iptables how do I fix it?
Hi guys I am changing host providers and I was running centOS 5.7 on my machine with the kernel 2.6.18-274.el5
On my new vps the kernel is 2.6.32.12 and the OS is centOS 5.6...they did not have 5.7
...
4
votes
1answer
88 views
What happens if a linux kernel argument is passed twice with different values?
As the question states, what if I pass
kernel /vmlinuz audit=1 audit=0
Will auditing enabled or disabled? Or will the kernel just freak out? Or is it undefined and will depend on the build of the ...
0
votes
0answers
268 views
How to write a netfilter kernel module and use it? [closed]
First, let me describe my application. Maybe I don't need to code anything. (Jump to "In Short" if impatient).
Application
I have a network (EtherCAT) that uses its own protocol of communication. It ...
4
votes
3answers
3k views
Interpreting cryptic kernel “page allocation failure” messages
I have a multi-user CentOS 6.1 database system running an application named ABC. The server is 64-bit, 8GB RAM and 6 vCPU (on VMWare ESXi 4). We get frequent dumps into the dmesg and the system logs ...
3
votes
2answers
265 views
How any routing protocol packet reaches(flows of operations) from NIC card (physical layer) to any Routing (OSPF/RIP/BGP) daemon?
The problem is rearding the routing protocol packet flow in any linux/unix device where multiple routing protocol daemons are running.
How any routing protocol packet reaches(flows of operations) ...
13
votes
2answers
16k views
Improving TCP performance over a gigabit network with lots of connections and high traffic of small packets
I’m trying to improve my TCP throughput over a “gigabit network with lots of connections and high traffic of small packets”. My server OS is Ubuntu 11.10 Server 64bit.
There are about 50.000 (and ...
1
vote
2answers
250 views
Issues debugging a kernel panic (custom kernel)
I'm looking to compile a custom kernel from the official source tree (kernel.org). The machine itself runs the latest stable RHEL kernel without issues but I can't seem to figure out why it's ...
0
votes
1answer
57 views
Understanding “forward” in linux
Which part of the linux is responsible for "forwarding" traffic between interfaces?
I know about "/proc/sys/net/ipv4/ip_forward" but which part of OS, kernel or a module is actually checking this ...
0
votes
0answers
142 views
Server is crashing - kernel panic - screenshot
Can anyone decipher whats going on in this screenshot : http://i.imgur.com/pJ8FV.jpg
My server keeps going down, my host rebooted it and took a photo of the monitor for me
Server config:
AMD 945 x4
...
0
votes
1answer
637 views
Is this a memory failure being logged (CentOS web server)
$ sudo tail /var/log/messages
Jan 30 13:47:58 www kernel: EDAC MC0: CE row 3, channel 0, label "": Corrected error (Socket=0 channel=1 dimm=1)
Jan 30 13:47:58 www kernel: EDAC MC0: CE row 3, channel ...
1
vote
1answer
274 views
debian package to ko file
I have downloaded hp-be2net_4.0.359.0-2_all.deb package which is used for NIC driver for linux.
I installed the above package using below command
dpkg --install hp-be2net_4.0.359.0-2_all.deb
Then ...
3
votes
4answers
612 views
Reloading a kernel “live” in CentOS / RHEL 6
When upgrading the kernel package on CentOS or RHEL 6, is it possible to load the new kernel without rebooting?
My gut tells me it's not, but if it were, it'd be handy - especially when compiling ...
3
votes
1answer
67 views
What is the way to update /lib/modules after copying disk to a different system?
I have transferred the disk of a a Hardyvirtual machine to another virtual machine with a different kernel but there is no equivalent of /lib/modules// on disk. How can the /lib/modules of the new ...
0
votes
2answers
492 views
Kernel Panic - not syncing :Attempted to kill init
I am facing this problem on my Debian5. I am running this server in Virtual Box.I have four os in this machine. But in this server only I get this message when I boot .
run init: /sbin/init : ...
0
votes
1answer
78 views
Debug kernel booting to blank screen
I have a machine which works fine with the precompiled 'generic' ubuntu kernel (3.0.0-13) but when I try to boot up the precompiled 'virtual' ubuntu kernel (3.0.0-13) it just puts me on a blank screen ...
1
vote
2answers
769 views
Kernel Printk: xx message suppressed
Hi I have a watchguard firewall, and I lost access to the firewall before xmas, therefore I visited the site, upgraded the firewall to the latest firmware but unfortunatly, I am now having similar ...
1
vote
2answers
2k views
Upgrading linux-headers-server and linux-image-server fails
apt-get upgradetold me that packages linux-headers-server linux-image-server were kept back, and thus this answer lead me to run apt-get install linux-headers-server linux-image-server.
However, the ...
-3
votes
2answers
224 views
Error in Virtual box with RHEL 6
While using Virtual Box in RHEL 6 at the time of starting virtual OS getting following error. Help me to resolve this.
Virtual Box version VirtualBox-4.1-4.1.8_75467_rhel6-1.i686
Operating System ...
2
votes
2answers
1k views
mkfs refuses to format device in the claim it's mounted when actually it is not
This is the problem:
root@ip-10-126-247-82:~# mkfs.ext4 /dev/xvda3
mke2fs 1.41.14 (22-Dec-2010)
/dev/xvda3 is mounted; will not make a filesystem here!
And this is the debugging:
...
1
vote
2answers
1k views
task blocked for more than 120 seconds
I'm getting a lot of stuff like this on my ec2 instance:
kernel: [141720.410047] INFO: task kjournald:14019 blocked for more than 120 seconds.
kernel: [141720.410205] INFO: task flush-202:112:2005 ...
6
votes
2answers
408 views
Kernel updates without rebooting
Similar to some of the topics touched on in this question, Rebooting servers for kernel updates, I was curious if there was a way in which one could apply kernel updates to the system without ...
0
votes
1answer
2k views
error: “net.ipv4.netfilter.ip_conntrack_max” is an unknown key
I have a problem on Ubuntu 10.04.3 LTS x64 with sysctl net.ipv4.netfilter.ip_conntrack_max
. If I run this command on shell, I get back an error:
error: net.ipv4.netfilter.ip_conntrack_max" is an ...
1
vote
0answers
316 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 ...
16
votes
2answers
846 views
What is the largest hardware clock update the Linux kernel “11-minute mode” can make?
When certain time-related programs (like ntpd) are running on a Linux system, the kernel will switch into so-called "eleven minute mode" (see the hwclock man page) whereby it will automatically update ...
1
vote
3answers
926 views
Reboot fails on RHEL 6.1 after kernel update on Amazon EC2
Everytime I start a new RHEL instance, I like to perform a yum update to start with the most up-to-date system. However, everytime I try to reboot the instance after that, the instance never goes ...
