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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26 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 ...
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21 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 ...
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7 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 ...
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1answer
17 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 ...
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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 ...
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2answers
33 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 ...
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14 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 ...
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1answer
90 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 ...
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34 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 ...
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1answer
89 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 ...
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35 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 ...
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45 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 ...
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2answers
20 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 ...
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0answers
79 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 ...
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26 views

DRBD device temporarily disappearing across different kernel versions?

After upgrading from an old kernel to a new kernel version and booting into the new kernel the DRBD logical device was gone. Think nothing under /proc/drbd. This is a major problem as I have DRBD ...
2
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1answer
49 views

Can't execute any command

I can't execute any command on my Debian server, for exammple if I try to execute "reboot" command I have this : root@server002:~# reboot -bash: /sbin/reboot: Input/output erro Or if I want to ...
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302 views

Ubuntu 14.04.2 LTS - Errors on apt-get autoremove old kernel images - dpkg and grub errors

I was running my usual apt-get update / apt-get dist-upgrade sequence on my Ubuntu 14.04.2 LTS server, and saw some old kernel packages marked for autoremoval. I frequently run apt-get autoremove to ...
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1answer
21 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. ...
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1answer
248 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 ...
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1answer
49 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
58 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
113 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 ...
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21 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 ...
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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. ...
1
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1answer
72 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
206 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
56 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
36 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. ...
0
votes
1answer
30 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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36 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
47 views

Debian diffence between kernels [closed]

Debian Wheezy installer What's the difference between the first and the second kernel?
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77 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 ...
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19 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
205 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
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3answers
154 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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25 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 ...
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1answer
146 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
105 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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2answers
308 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
52 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
70 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
129 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
votes
1answer
52 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 ...
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0answers
100 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
120 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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105 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 ...
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1answer
74 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
108 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 ...
0
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1answer
44 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 ...
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1answer
49 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 ...