Questions tagged [kernel]
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 components).
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Number of receiving queues is double the number of cores of my server?
I'm using Mellanox ConnectX-5 100 GB NIC, Linux kernel 5.15 and my server has 32 cores (SMT disabled). But in the /sys/net//queues, the number of rx queues is 64, which is double the number of cores ...
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Can we use fdisk to partition a disk bigger than 2 TB without recompiling the kernel?
Here is my problem.
Our operating system is Debian 11. The main hard disk is doing fine.
I have a 6TB external volume. If I choose to use parted to format this disk it will entail recompiling the ...
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Saving contents of /proc/net
I'm trying to archive files from /proc/net when a process crashes. This is to aid in debugging, to get understanding about the machine status when crash happened.
The contents are not regular files, ...
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kernel messages are complained about memory.inspite all DIMM cards was replaced
we have few DELL machines ( with RHEL 7.6) , and as we replaced the DIMM cards on machines because the Erros that we seen from kernel messages
after some time we checked again the kernel messages and ...
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May I ask during runtime how to check the some kernel command line parameters which not set in the grub but have a default value?
I notice there are some kernel command line parameters like below, which from Manual:
audit= [KNL] Enable the audit sub-system
Format: { "0" | "...
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iSCSI shared disks with custom device name on clients
I'm using RHEL 7.9 (Maipo) and need to setup for all iSCSI clients the same device name, like /dev/sdb or /dev/thiscustomname.
I could do that by sharing the source disk using multipath, but for Db2 ...
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RHEL + how to capture fresh kernel message without machine reboot
here is example from dmesg output from important production server ( RHEL 7.2 - DELL machine HW )
as we can see the sde disk in server is dying
[Wed Jun 30 11:24:58 2021] sd 0:2:4:0: [sde] tag#0 ...
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SLURM / NFS based computing cluster with disk uniterruptible sleep issues (state : D)
Context :
We have a computing cluster based on 7 servers, running Debian 11:
a storage (HDD NAS, ~500TB, RAID5, LVM)
a frontal server, running SLURM, nfs-common
5 nodes on which the storage is ...
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cat /proc/pid/cmdline hangs (no cgroups, no nfs or network fs, no memory issues)
We are a bit stumped.
Once in a while ps/w hang forever (at least an hour) on our server, and it is on reading /proc/pid/cmdline for a process (happend twice today, verified with strace cat directly ...
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RHEL server + what is the meaning of the kernel messages about Hung TX queue XX
We have 524 RHEL machines. in our Hadoop cluster ( all machines are DELL HW )
all machines are RHEL 7.2 version (old kernel version)
uname -r
3.10.0-327.el7.x86_64
last week we seen the following ...
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Why do some servers have /etc/sysconfig/kernel and others do not?
I spent some time looking into this and couldn't figure out why there are servers with and without /etc/sysconfig/kernel.
What's particularly interesting is that we have some servers with the same ...
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Clear RAM Memory Cache and buffer on production Hadoop cluster with HDFS filesystem
we have Hadoop cluster with 265 Linux RHEL machines.
from total 265 machines, we have 230 data nodes machines with HDFS filesystem.
total memory on each data-node is 128G and we run many spark ...
- 479
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Linux server loses network connectivity after an OOM event
We have a server runnnig Linux 5.15 and we've had multiple verified situations where a process is killed by OOM and that leaves the whole system inaccessible on the network, both for inbound and ...
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kernel message + how to know if we need to replace the DIMM based on kernel messages
we have RHEL 7.6 server , and we noticed about the following kernel messages.
[1065085.048872] EDAC sbridge MC0: PROCESSOR 0:406f1 TIME 1676989040 SOCKET 0 APIC 0
[1065086.052107] EDAC MC1: 0 CE ...
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Issue with i9-10900TE while activating PAE on linux kernel 5.15.x
I've to compile a linux 32b kernel 5.15.86 RT56 for running on 2 different computers with Intel CPUs : one with an i7-9700TE and 32Gb RAM, and the other one using an i9-10900TE with 64 Gb RAM.
I need ...
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Reusing Virtual Network Devices across different customers
I am trying to reuse virtual networks(made of virtual linux network devices) across customers. I am facing issue where we are not able to find if there is any network packet from previous customer is ...
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Explain of OOM killer logs
I have a question about the OOM killer logs. We are expecting a lot of OOM kills.
The ecosystem
My ecosystem looks like below:
I have a server with 4 cores and 8 GB of RAM.
I am running there the ...
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Is the outgoing connection from a OpenVPN client to a LAN behind an OpenVPN server forwarded by the server kernel?
I've observed a somewhat strange behavior that I can't quite understand. So I set up an OpenVPN connection as shown in the graphic below. (It's a TUN and client-to-client setup).
My thoughts are ...
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Fix kernel issues in rescue mode
I have updated the kernel in a VPS Centos 7, and after rebooting, the machine is not responding anymore, including with SSH.
I connected to the VPS via a temporary rescue linux machine from where I ...
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How to tell whether a linux tcp socket had recent activity?
Most of the time, when changing or upgrading a network service, I would do this during maintenance hours but some services are rarely used so it is tempting to just check whether it is currently in ...
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How can I find the full list of acceptable `boot=` option of kernel?
I usually see options like boot=casper or boot=live. However, I cannot find anything describe the actual meaning of this option and I cannot find any piece of code handle this option at all. From ...
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how can I list all static builtin drivers in kernel, such as pcieport and pciehp?
with lspci I can see things like:
Slot: 00:02.0
Class: PCI bridge [0604]
Vendor: Red Hat, Inc. [1b36]
Device: QEMU PCIe Root port [000c]
Driver: pcieport
In dmesg I can see pcieport 0000:00:02.0: ...
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Kernel 6.0 and AMD-GPU/Notion app issue
Recently I installed the new linux kernel 6.0.2 on my Manjaro laptop.
After using my usual apps for a while, I notice the laptop "freezed" and only a forced power off got it back.
Looking ...
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How can I update php 8 on a linux server without internet access?
Operating System: Redhat 8.4
Internet access : no
access to redhat server : ssl vpn
Current php version : 7.4
Purpose: Make php version 8
How can I do that ?
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Ifconfig result on the server running PF_RING with zerocopy
I have an application which uses PF_Ring zero copy as a part of its packet sniffing capability. When this application is running would it be possible to find out the amount of RX/TX traffic using ...
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RHEL 7.9 and OS compatibility with DELL server GEN 15 PowerEdge
we want to purchase the dell servers Gen 15 machines ,
total machines should be around 85 servers
these servers should used for Hadoop cluster as data-node machines
and the OS should be RHEL 7.9 ...
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dmesg tells 1G out of 128G available?
I have a 128GB RAM server, kernel 4.18.0-305.7.1.el8_4.x86_64,
"dmesg | grep Memory" outputs as follows:
[ 0.000000] Memory: 1282732K/133708404K available (12293K kernel code, 2225K ...
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Is there a utility for detecting temporary system freezes?
Is there a (unix) utility which is able to detect temporary system freezes by observation?
E.g. I could imagine an utility which continuously fetches the system time, sleeps for a specific amount of ...
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Is there any Windows Boot Log documentation besides how to enable it?
I have a Windows 2019 Server that is failing to start the AFD service which is preventing the system from booting in normal mode. In general, the advice online to run a ton of Microsoft Auto-repair ...
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Centos 7: (re)discover SCSI device removed by kernel
I have a PowerVault with a RAID 5 array attached to a PowerEdge server running CentOS 7.9.2009.
One of the disks in the array failed and apparently the kernel then removed the array. Here are some ...
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Module ip_tables not found after upgrade
Since I upgraded recently my Ubuntu server from 20.04 to 22.04 I have an issue with Docker. Docker will not start any more after reboot, because of the ip_tables module.
After every reboot of Ubuntu ...
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Unknown kernel command line parameters "BOOT_IMAGE=/vmlinuz-5.18.11-1.el7.elrepo.x86_64", will be passed to user space
On CentOS 7, after upgrading the kernel to version 5.18.11, I observed the below message in /var/log/messages:
Unknown kernel command line parameters "BOOT_IMAGE=/vmlinuz-5.18.11-1.el7.elrepo....
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Is it possible to read less than 4 bytes from TUN device when IFF_NO_PI is not set?
I was reading the implementation of wireguard-go, and found it handles reading less than 4 bytes from the TUN device file when the no packet information flag is not set.
I wonder is it possible that ...
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RHEL + can we improve disks performance by tuning kernel parameters?
we have Hadoop cluster and we are collection metrics collection data in order to investigate slowness behavior on spark applications
after long investigation on our Hadoop cluster
we noticed from ...
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Is a value of 18446744073692774399 normal for kernel.shmmax? [duplicate]
Context: web server hosted on DigitalOcean with a PostgreSQL database.
We were experiencing recurring database crashes for unknown reasons. Eventually I nailed down a faulty query that was overloading ...
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Invalid argument received when running chown in a Linux namespace
After running something like this:
unshare -rUm
mkdir opt
mount --bind opt /opt
touch /opt/test
chown 1000:1000 /opt/test
I'm receiving this:
chown: changing ownership of '/opt/test': Invalid ...
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How to verify if cgroup tree is writable?
I'm trying to follow this documentation and I'm struggling to understand how can I make the cgroup tree writable or how I can verify it.
In that documentation, I have a link towards how can I allow ...
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GNU Linux Debian 11 (should work for Ubuntu too) - compiling latest kernel (Linux/x86 5.17.7) - results in Volume group "name-vg" not found
Dear internet & users & robots & AIs & other entities with access to digital,
one fine day... decided to compile the latest currently available kernel under Debian 11.
last time did ...
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what's root cause of "A start job is running for Create Volatile Files and Directories"
Stuck at "A start job is running for Create Volatile Files and Directories" after reboot a server(Debian 9.5, 64bit), and solve by this "boot-stuck-at-a-start-job-is-running-for-create-...
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How to cleanup /usr/lib/modules and /usr/lib/x86_64-linux-gnu?
I executed the command apt autoremove but those folders persist.
As the command "du -h -x --max-depth=1 /usr/lib | sort -hr | head -n 10" showed me, they are currently using almost 1G each:
...
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Stuck on "update-initramfs: Generating /boot/initrd.img-5.4.0-92-generic"
I have a problem with uninstalling packages on my server(20.04 LTS).
When I run apt remove metricbeat receive this message:
root@elk:/home/elk# apt remove metricbeat
Reading package lists... Done
...
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Unable to get kernel log messages written to a specific log file on syslog server
I have a working rsyslog setup with CentOS as my server and I am using Kali as the client.
I am able to use logger on Kali to send test log messages and see the log messages appear in the CentOS ...
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Debian kernel upgrade issue
I was checking my Debian 11 bullseye kernel if i have fix for Dirty Pipe vulnerability. Seems that kernel version 5.10.102 has the fix for that.
Problem is that i cannot get upgrade for that kernel ...
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Debian: Kernel update using APT - reboot required to take effect?
Suppose I update the kernel of a running Debian system using apt-get upgrade linux-image-amd64 to a higher minor version number (e.g., 5.10.10 to 5.10.11). Do I have to reboot the Debian server in ...
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only flush the write cache if there's no read activity
Normally the Linux Kernel flushes the write cache if a specified time limit is exeeded or the cache is full. This leads to stalling with HDDs since the writing process makes reading processes much ...
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Server experiencing Kernel-Power Event 41, but only once every two weeks
I go to check on a client's servers once every two weeks as part of an IT contract. For the past month and a half, their secondary server will experience a sudden shutdown and generate the Critical ...
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How can I get my CPU to run at maximum speed by circumventing CPU scaling? [closed]
I am running CentOS 7 (7.9.2009) (kernel 3.10.0-1160.49.1.el7.x86_64) on a rather old laptop (Lenove T61) with a dual core CPU (Intel(R) Core(TM)2 Duo CPU T7300 @ 2.00GHz). The driver for CPU scaling ...
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what are the kernel messages about "Disabling DIF Type 2 protection" means
On our RHEL 7.2 server we saw a strange kernel messages with lines as:
Disabling DIF Type 2 protection
***10DIGITS*** 512-byte logical blocks: (2.00 TB/1.81 TiB)
Above messages are relevant for all ...
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Can't run docker-container 'failed to create endpoint frosty_varahamihira on network bridge'
When I try to run the hello-world docker image I get the following error:
ubuntu@ubuntu:~$ sudo docker run hello-world
docker: Error response from daemon: failed to create endpoint frosty_varahamihira ...
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needrestart keeps asking for rebooting on new kernel
I have removed obsolete kernel after new kernel was installed. Now I keep getting following message from needrestart over and over again:
The currently running kernel version is 4.9.0-16-amd64 and ...
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