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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3answers
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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 ...
2
votes
1answer
138 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 ...
5
votes
2answers
5k views

What is creating the generated/autoconf.h?

We're trying to build a piece of software that demands the kernel source, not just the headers. So we downloaded the kernel source via the centos src rpm. However the autoconf.h is missing. We tried ...
0
votes
1answer
52 views

Diskless node. Unable to mount root fs via NFS

Server: CentOS 7 NFS root filesystem for client and Kernel: Slackware 14.1 I enabled "Root file system on NFS" and "IP: kernel level autoconfiguration" with "DHCP,BOOTP,RARP" support, recompiled the ...
3
votes
3answers
5k views

CentOS 6.5 new Kernel not active after reboot

Today I was running some yum updates and wanted to verify that everything went through fine by making sure I had a new kernel. To my surprise I noticed that CentOS was still running ...
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votes
1answer
35 views

Linux Server: Too Many Open Files

I have an application running on Linux Server. But server suddenly stopped responding but when I ping from other machine to server it allowed to ping but was not allowing to login into the server. Not ...
3
votes
2answers
748 views

CentOS 6.6 (Final) - yum kernel upgrade troubles

Well-being everybody, I'm a SysAdmin Junior managing 3 CentOS Virtual (Web)Servers, this morning I'm facing some troubles with package manager yum. As usual operation, this morning I've run the ...
0
votes
1answer
41 views

IBM - Kernel problems [closed]

I bought an IBM x3850 and wanted to install Ubuntu on it. Then it said, that it can not find hard drives... After some time i figured out that I need to type in the kernel parameter iommu=soft. The ...
0
votes
1answer
35 views

Simpler way to add eth0 support in initrd.img (Centos)

I am trying to deploy clone image via pxeboot on hard disk. For this I want to use dd tool. I am aware that there are few tools like fog and clonezilla which does similar thing but this is university ...
2
votes
0answers
157 views

How to disable perf subsystem in Linux kernel?

I'm running some benchmarks. My benchmark runner monitors the dmesg buffer between experiments, looking for anything which could impact performance. Today it threw this up: [2015-08-17 10:20:14 ...
0
votes
0answers
12 views

Xubuntu - Kernel panic [migrated]

I'm getting a sudden kernel panic error out of no where. I even tried Boot-Repair but ended up with no luck Here's my boot-repair information - http://paste.ubuntu.com/12107541/ I'm wondering is ...
2
votes
2answers
3k views

CentOS 6 Xen guest fails to boot after 'yum update'. Kernel?

I Seem to be having an issue with a Xen guest not booting after a yum update. DomU Configuration: #kernel = '/boot/solus-vmlinuz' #ramdisk = '/boot/solus-initrd.img' bootloader = ...
4
votes
1answer
279 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
1answer
60 views

Linux ext3 Directory index full - internals

Encountered a situation today on a server that has me wondering. Here's the scenario: Syslog shows: kernel: EXT3-fs warning (device sdb2): ext3_dx_add_entry: Directory index full! Found the ...
0
votes
0answers
13 views

OOM Killer when tcpdump is run in system with low memory

I am working on an embedded system with limited memory. Here is the dump from my vmstat: procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff ...
2
votes
2answers
3k views

How to find which HD controller module a running Linux system is using?

I have a problem with an HP ProLiant Microserver that won't boot with a Slackware 12 system using Linux 2.6.21.5 If I boot a recent version of System Rescue CD, the disk is recognized. So my ...
0
votes
0answers
42 views

Debian Jessie 8 idle on fresh install always a little too high, shows rcu_sched ksoftirqd kworker causing cpu load

Are the days of 0.0 cpu load on an "idle" server gone? I have another server (centos/redhat) 32GB ram that actually runs apache/MySQL/Lamp, mono, redmine/ruby, and other junk and its still shows me ...
1
vote
0answers
16 views

/proc/stat btime value change after boot

In a Linux server with the kernel 3.16, not virtualized, but with the ntp daemon active, the variable "btime" wich gives the time at which the system booted, change a few seconds before booting. For ...
3
votes
1answer
1k views

CentOS Tuned Equivalent For Debian

Running a few systems, a few are Debian which have been great. I have on the CentOS boxes tuned(tuned-adm) installed and setup for throughput. I searched all over Google and only found some articles ...
28
votes
2answers
16k views

Damaged /vmlinuz and /initrd.img symbolic links after Kernel uninstall

OS: Ubuntu 8.04 LTS Server Edition We just rolled back an kernel update using the following command: sudo apt-get remove linux-image-2.6.24-24-server The uninstallation was successful, but it had ...
0
votes
1answer
33 views

convert SLES11 SP1 vmlinuz-3.0.13-0.27-xen to VMware using vmware converter

I am looking to convert a XEN VM (SLES11 SP1 kernel vmlinuz-3.0.13-0.27-xen) to a VMware guest using the VMware converter tool. The VMware tool tell me conversion went fine. 100% OK, however, when I ...
1
vote
1answer
52 views

cpufrequency scaling with debian 8.1 and Intel XEON E5-1650 v3

I want my server with debian 8.1 not to use cpu scaling but always run at the highest possible frequency. I have installed cpufrequtils $ dpkg -l | grep cpufreq ii cpufrequtils ...
1
vote
3answers
850 views

debian kernel upgrade to 2.6.32-5-amd64 but uname still shows 686

I'm try to upgrade a debian system to 2.6 64 bit kernel with the command aptitude install linux-image-2.6.32-5-amd64 which works fine. The system reboots, /vmlinuz -> boot/vmlinuz-2.6.32-5-amd64 ...
0
votes
1answer
62 views

centos doesn't reply to icmp request

I have the following situation: Centos7, 2 NIC with following setup: em2(NIC2) : 82.79.24.74/29 82.79.24.75/29 em3(NIC3) : 192.168.0.240/24 192.168.133.240/24 ...
0
votes
1answer
39 views

Rebooting a production CentOS 6 server that's been up for 365 days

I noticed today when running uptime that my server has been up for exactly 365 days. Which led me to google "should I periodically reboot my server". Which led me to the knowledge that YES, I should ...
0
votes
0answers
149 views

task nginx:4164 blocked for more than 120 seconds

My server was working fine for 173 days then it started to happen. Upgrading CentOS 6.6 kernel to latest one didn't helped. Rebooting helps for about 10 minutes then it starts all over again. I'm ...
0
votes
1answer
5k views

Fatal: module iscsi_trgt not found — trying to get my iscsi target to run on debian

My server info: Linux Microknoppix 2.6.39.3 #21 SMP PREEMPT Sat Jul 23 09:48:39 CEST 2011 i686 GNU/Linux modprobe iscsi_trgt results in FATAL: Module iscsi_trgt not found. So I run # ...
-1
votes
1answer
23 views

AWS Instance Kernal-id

I am running a Windows Server instance in AWS Cloud.I have created a snapshot for the same. When i'm trying to create a AMI from my snapshot it is asking Kernel-ID and RAM Disk ID. I don't know what ...
0
votes
1answer
105 views

Debian/Installer Preseed Remove Post Install Kernel Options + Multi NIC Preseed Tip

In light of recent automation trends, I would like to be able to fully automate an install of Ubuntu. My my first problem was auto selection of the bootif with multiple NICs break Ubuntu/Debians ...
2
votes
1answer
90 views

CentOS, kernel: out of memory

Hope you can help me with the following problem. We are running a CrushFTP service on a CentOS release 6.6 (Final) system. But nearly every week the service crashes. So I take a look at the logs and ...
1
vote
0answers
33 views

slabtop command doesn't work

I've inherited Sys Admin duties on webserver and I'm a bit of out my element, but learning as I go. My newest issue is all the of the ram has been gobbled up and I'm not sure where it has gone. free ...
0
votes
0answers
22 views

How to hot add a new disk with virsh attach-disk?

I'm trying to add a new LVM disk to my guest machine (Ubuntu 14.04.1) by doing the following on the host: lvcreate -L 14G -n vm_vm005_data3 vg00 virsh attach-disk vm005 /dev/vg00/vm_vm005_data3 ...
5
votes
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 ...
0
votes
1answer
67 views

snmpd does not update date due to filesystem access error in new ubuntu versions

My Cacti stopped graphing network data for servers that I monitor using snmp. I am able to manually query the corresponding counter using snmpget $ snmpget -v 2c -c XXX XXX .1.3.6.1.2.1.31.1.1.1.6.4 ...
0
votes
0answers
14 views

disabling ip_forward for ubuntu server

This is the state of my server right after booting: root@vzu01-ubuntu:~# uname -a Linux vzu01-ubuntu 3.16.0-30-generic #40~14.04.1-Ubuntu SMP Thu Jan 15 17:43:14 UTC 2015 x86_64 x86_64 x86_64 ...
1
vote
2answers
95 views

Wchan section in ps output not showing anything

I know that if a process go into D state then it means that it is in uninterruptable state. The process can not be killed by any signal. It will only come out of that state on reboot or if I/O wait is ...
0
votes
1answer
2k views

An oom killer that I cannot explain

I am not able to understand why would kernel issue this oom killer when I see enough memory is available: I say enough memory is available after looking at Normal DMA Normal free lines This is an ...
0
votes
1answer
165 views

Building CentOS 6 kernel with KVM support fails due to MMU

When building the latest Linux kernel for CentOS it turns up the following error CC [M] arch/x86/kernel/iosf_mbi.o CC arch/x86/kvm/../../../virt/kvm/kvm_main.o CC ...
0
votes
0answers
104 views

Add nmi=ignore to default xen boot option

I updated my Xenserver from 6.2 to 6.5 and the server won't boot unless I deactivate Hyper Threading via BIOS (INtel Server Board). I can fix that using a special kernel parameter (nmi=ignore) but I ...
0
votes
1answer
251 views

Debian 8 Jessie with older Kernel - Do I have to expect problems?

I have a virtual server that I tried to upgrade from Debian 7 to Debian 8. Unfortunately, I cannot use the new kernel: it still uses version 3.2.41-042stab108.2. Everything else seems to have been ...
4
votes
1answer
9k views

How to force Debian to boot new Kernel?

I'm running Debian 6, Debian GNU/Linux, with Linux 2.6.32-5-amd64 under Grub2 ( 1.98+20100804-14+squeeze1) on a remote system (no possibility to view the pre-boot messages). I compiled and installed a ...
0
votes
1answer
124 views

How can I modify kernel command line in CoreOS

I am trying to set 'net.ifnames=0' on the kernel command line for CoreOS. In older loads (including the current stable 647.0.0), you could mount /dev/sda1 and edit the grub.cfg file under ...
0
votes
1answer
692 views

How to auto-start Degraded Software RAID1 under Debian 8.0.0 on boot?

If you remove a component HDD from an array, it drops into a "busy box" shell under "(initramfs)" saying something similar to "cannot mount root device" as the RAID1 array becomes "inactive". It is ...
1
vote
2answers
542 views

grubby fatal error: unable to find a suitable template

I'm trying to fix my system after moving it from one server to another. It works perfectly with kernel booted via network, but not from the disk. Reinstalling stock CentOS 6.6 kernel shows this ...
25
votes
4answers
60k 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 ...
0
votes
1answer
379 views

Effects of IW10 (initcwnd 10 initrwnd 10) on high speed LAN based TCP/IP communications?

What does changing the number of packets sent during the initial congestion window to 10 have on LAN connections? Via: ip route change default via GATEWAY dev INTERFACE initcwnd 10 initrwnd 10 Is ...
0
votes
1answer
28 views

Upgrading Web Application's Systems' Kernels for IW10 & other related improvements - upgrade all machines? LB first? Most important?

Stackers - We're making the push to upgrade the systems for our web app to take advantage of the various TCP improvements becoming more readily available (e.g. ...
3
votes
2answers
2k views

VMWare ESXi error upon boot “Relocating modules and starting up the kernel”

Coming back from a 4-day weekend, I noticed the A/C had been turned off for the duration of the long weekend and the heat was around 80-82 degrees. The HP ProLiant DL185G5 was running but the system ...
0
votes
2answers
22 views

Posix map fs path to syspath

Is there a safe way to map a filesystem path to a /sys/block/ node. For instance on my system (Ubuntu) my / path is mounted from /dev/disk/by-uuid/7f6a93a7-1e63-48a3-a7e3-b336a2f9dbf7 which is a ...
0
votes
0answers
91 views

Kernel upgrade issue

I am trying to upgrade kernel on OnApp VM. Currently installed kernel is 2.6.32-279.22.1.el6.x86_64. The new version available is 2.6.32-504.16.2.el6.x86_64. I installed new kernel ...