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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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 ...
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31 views

How to build a Raspberry Pi CubeSAT? [on hold]

Guys I want to build a demo Raspberry Pi CubeSAT setup. This thing I need to setup on my home-lab to research on TrafficSqueezer WAN optimization over CubeSATs. Does anyone did CubeSATs or experience ...
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1answer
46 views

I need to perform a kernel upgrade on a live system. Best practices? [closed]

Steps taken so far: apt-cache search linux-image* apt-get install linux-image-... I was now thinking of rebooting and selecting the new kernel when it appears on the GRUB menu, however: Is it ...
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1answer
38 views

VPS restarted for no reason. Why?

I have a VPS that runs a Java server, a redis server and a PostgreSQL server. Everything is running well but last night my server "crashed" at 3:15:50 AM. At least that's what I thought. I looked at ...
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3answers
66 views

Best way to disable swap in linux

I am running a custom compiled 3.18.9 kernel and I am wondering about the best way to disable swap on the system. I also use init if it makes a difference. Is it enough to comment or remove the swap ...
0
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0answers
7 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
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0answers
9 views

Seeing what Linux kernel compile options where used [duplicate]

Is it possible to tell what compile options a running Linux kernel has been built with? I am particularly interested in those that impact on preemptive behavior, such as CONFIG_PREEMPT_VOLUNTARY. ...
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1answer
41 views

TSC missing from available clocksources

Not sure why TSC as a clock source is not available? cat /sys/devices/system/clocksource/clocksource0/available_clocksource hpet acpi_pm The CPU I'm using is Intel Xeon(R) X5570 @ 2.93GHz. The ...
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1answer
62 views

Kernel: dst cache overflow

I'm under continuous floods at time that are generally of lower magnitudes. I've observed my system often to become totally unresponsive on its network while I observed this in the logs, kernel: ...
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0answers
45 views

Kernel panic under DDOS

I'm running a Debian 6 - 64bit system (Kernel 2.6.32-5-amd64) and often get flooded with DDOS. I have tuned the network parameters under /etc/sysctl.conf to not let any kernel parameter overflow. ...
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0answers
29 views

switch_root not included in initramfs image

After upgrading the kernel via yum to the latest version the initramfs image file is missing the switch_root binary from the /sbin/ folder. This causes the machine to not boot, from this kernel. ...
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1answer
29 views

IO does not share in multiple CPU

In my linux server IO doesnot share in multiple CPU. as below output ata_piix intrupts share in only cpu0 [root@manage ~]# uname -a Linux manage 3.14.24-1smp #12 SMP Tue Mar 17 15:33:27 IST 2015 ...
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0answers
22 views

Why would kern.log stop logging after crash & reboot

Server: Ubuntu 12.04 I recently noticed that my servers kern.log had stopped logging. I've not separated iptables from the kern.log so it used to be very active, however recently it's been logging ...
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1answer
38 views

Debian diffence between kernels [closed]

Debian Wheezy installer What's the difference between the first and the second kernel?
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0answers
33 views

detecting whether GPUs are accessible before running nvidia-smi during boot to create dev files

In the past, I've successfully configured Ubuntu systems containing NVIDIA GPUs to launch nvidia-smi in the background from within /etc/rc.local during the system boot to create the requisite ...
0
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0answers
18 views

Run compiled kernel with mcp251.x support

I have jetson tk1 board with ubuntu 14.04 pre-installed. I want to add mcp2515 functionality to it. How can I get it running? First of all, I set up the support of can bus in kernel and make and ...
0
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1answer
114 views

SSD caching using bcache or dm-cache on kernel 2.6.32-042stab104.1

I'm looking to use bcache or dm-cache with the latest OpenVZ kernel (2.6.32-042stab104.1) on CentOS 6. Unfortunately, dm-cache and bcache are part of kernel 3.10, but I know the OpenVZ kernel has a ...
0
votes
3answers
74 views

Kernel Processes Periodically Eating CPU During High Load

I run a production web server with 24 cores in which the work is both CPU and I/O intensive, but mostly CPU. My scripts delay execution when total CPU load is ~85% or higher in order to keep the load ...
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0answers
20 views

Broadcast ARP weirdness

we a running a router on a custom Linux box. Kernel is 3.14.14. What happens is that when you arping the router in broadcast only mode is the router has a verey slow response time: # arping -b -c ...
0
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1answer
60 views

Compiling an individual kernel module (Debian/Ubuntu)

I need to modify the ELF loader's kernel implementation of an Ubuntu 14.04 distribution. Having downloaded the sources using: sudo apt-get source linux-image-$(uname -r) I ran the configuration ...
1
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1answer
45 views

how to debug futex congestion in system

I have perl multithreaded script ("assp antispam proxy") that uses multiple perl libraries. On one of my servers after about 2 hours script starts to make huge number of futexed which consumes a lot ...
0
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1answer
137 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 ...
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0answers
27 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 ...
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2answers
61 views

Can a Linux Kernel be shared between two operating systems?

Quite simple question. I am working on a project to have multiple operating systems (all linux) on the same machine using btrfs subvolumes so that the user can boot to the environment they are ...
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0answers
72 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) ...
2
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1answer
44 views

Use VPS provider's kernel or maintain my own?

I've got a Debian Wheezy VM on Linode and they run it with their own kernel. As a reputable company, I'm sure they're quick to apply security patches, and all I need to do is reboot to get the new ...
1
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0answers
77 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 ...
0
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1answer
83 views

New linux with old kernel in chroot [closed]

I have access to enterprise level server, but it have kernel version Description: Red Hat Enterprise Linux Server release 6.4 (Santiago) Release: 6.4 Codename: Santiago ...
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0answers
80 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
1answer
40 views

Enable IP forwarding inside an OpenVZ container but disable it on host

Is it possible to enable IP forwarding inside an OpenVZ container but keep it disabled in host system? I understand that OpenVZ containers and host share kernels, but I can use sysctl to set ...
2
votes
0answers
79 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 ...
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1answer
32 views

What does the tcp_fastretrans_alert error mean?

I found this error a couple of times in /var/log/messages after experiencing some odd TCP behavior: For some reason, if I connect to for example SSH for the first time in say an hour, the connection ...
0
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1answer
47 views

Which is the physical device behind the logical /dev/___ device

From time to time I get myself dealing with this same problem: from a linux logical block device (something below /dev/), I need to find the actual hardware behind it (something probably being listed ...
1
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0answers
39 views

make linux kernel read swap back into memory [closed]

Occasionally, I run a script that uses the majority of the 16GB of physical memory on my workstation. The kernel then swaps out the rest to swap partitions on multiple disks. After the script is ...
3
votes
1answer
1k 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 ...
1
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1answer
49 views

Influence of kernel code execution to Load average in top?

I'm trying to tests the amount of CPU that iptables use for NAT. Perhaps it will be more accurate to say "the amount of CPU that the netfilter kernel module" uses. The approach i took was to try and ...
3
votes
1answer
57 views

How to keep specific old kernels around after a yum update

I know that in CentOS 6.x, you can put the following line in /etc/yum.conf which tells yum to keep the last N kernels (by default this is set to five): installonly_limit=5 However, there are cases ...
15
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2answers
307 views

Does the “bs” option in “dd” really improve the speed?

Every now and then, I'm told that to increase the speed of a "dd" I should carefully choose a proper "block size". Even here, on ServerFault, someone else wrote that "...the optimum block size is ...
1
vote
1answer
31 views

Kernel dependency error on Ubuntu 12 server

I was doing my quarterly updates of an Ubuntu 12 server. After an apt-get update succeeded I'm getting this error running apt-get anything. Depends: linux-image-server (= 3.2.0.72.86) but it is not ...
0
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0answers
31 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 ...
4
votes
3answers
179 views

Modifying kernel cmdline in Ubuntu

I have a number of systems on which I need to modify the kernel cmdline, adding a few options. At the moment I do it using the following procedure: Open /etc/default/grub Modify ...
2
votes
0answers
846 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 ...
1
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1answer
142 views

dspam crashes with “general protection” kernel error [closed]

I use DSpam with Postfix. Recently DSpam started to crash with the following error in syslog: Nov 16 14:10:55 home kernel: [ 133.042190] traps: dspam[1692] general protection ip:7f63a493f3b0 ...
0
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1answer
62 views

General protection fault by __d_drop following SMTP attack

The SMTP port (Postfix) of my box running 3.16.5 is being hammered. The log repeats this over and over: Nov 14 09:16:25 [postfix/smtpd] lost connection after UNKNOWN from unknown[177.43.41.74] Nov 14 ...
4
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1answer
85 views

Solaris kernel parameter equivalence to Linux

I have set the following tcp kernel parameters in Solaris ndd -set /dev/tcp tcp_ip_abort_interval 120000 ndd -set /dev/tcp tcp_rexmit_interval_max 15000 ndd -set /dev/tcp tcp_rexmit_interval_min ...
0
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3answers
112 views

Why I should prevent yum from update kerneI?

I was googling about yum and reading some articles when I stumbled on bunch of articles about disabling yum from update kernel packages. Now I'm wondering why I should do that. When I update system I ...
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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), ...
1
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3answers
108 views

delete millions of files within a directory [duplicate]

The other day I ran bleachbit on my system. I had enabled wipe disk space option in it. It took several hours and my disk space filled up completely (100GB or so). After waiting forever, I decided to ...
0
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0answers
123 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 ...
1
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1answer
446 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 ...