The Linux kernel is the operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software.

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Warning :mounting fs with errors, running e2fsck is recommended

Linux server will hang and when I restart it will take around 2 hours to come up and resume normal operations. I checked the system log files and found mounting fs with errors, running e2fsck is ...
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2k views

How to disable ipv6 support in Linux entirely?

We are currently setting up a some local network servers to run in a full ipv4 network. I can be sure, that this network don't have ipv6 support, and never will. Next to that, partially because of ...
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358 views

Windows multicast NLB with Linux clients

I'm (on behalf of a client, anyway) having some troubles with Linux accessing a multicast NLB cluster hosted on Hyper-V (waiting for more information on what version, but I don't think the version is ...
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126 views

Unidentifiable processes under Redhat Linux

Upon issuing a ps ax command on a server I see the following processes that I can't identify. Googling them yields nothing useful. Does anybody know what these are or how I would track them down? The ...
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1answer
718 views

enable fanotify on oracle redhat linux kernel 2.6.39-400

As a newbie in linux environment, I am trying to install clamav daemon, which is clamd, on oracle redhat linux 6 kernel EUK 2.6.39-400. It needs to have fanotify enabled in the kernel. As I see there ...
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148 views

The default value for vm.dirty_background_ratio

Wondering why the default value for "vm.dirty_background_ratio" from Linux Server (CentOS and Ubuntu) is set to 40. Is this just a recommendation for safety? Or is there any particular reason why? ...
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193 views

linux not replying to an arp request

I am running linux 3.14 on a system with 2 interfaces. on the first interface, i can access our local network. on the second interface, arp packets come in but linux doesn't send out reply. is it ...
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2answers
232 views

View full program command line arguments in OOM killer logs

Is it possible to view full program command line arguments in OOM killler logs ? What I see now in /var/log/syslog is Memory cgroup out of memory: Kill process 29187 (beam.smp) score 998 or sacrifice ...
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78 views

Apply patch to custom kernel manually [closed]

I compiled a RHEL based kernel with a script. I've come to know that our version of kernel is vulnerable to attack and we need to apply security patches. https://rhn.redhat.com/errata/RHSA-2014-1392....
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Cause of page fragmentation on “large” server with xfs, 20 disks and Ceph

Any insight from someone with a bit of experience in the linux IO system would be helpful. Here is my story: Recently brought up a cluster of six Dell PowerEdge rx720xds to serve files via Ceph. ...
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192 views

task fstrim blocked for more than 120 seconds

I'm experiencing random crashes on my system. I've narrowed the problem to the fstrim program that's launched weekly by cron. In the console, I've got a set of blocked tasks among whigetch I find ...
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320 views

shorewall can'T start: UNTRACKED state requires Raw Table in your kernel and iptables

I'm trying setting up my firewall and installed and configured shorewall. Unfortunately I tried to directly configure iptables first, but this didn't work. When I start shorewall, I get this messages ...
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dummy network interface in Linux

When i create a dummy network interface and then bring it up it show up being in UNKNOWN state: root@5b8dd2855a9c:# ip l a boom type dummy root@5b8dd2855a9c:# ip l show boom 58: boom: <BROADCAST,...
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0answers
118 views

“Nosy Neighbor” and the CFQ scheduler

I'm trying to understand how does using CFQ affects the "Nosy Neighbor" problem. I'll ask it a bit naively, can a "Nosy Neighbor" even exist when using CFQ? Isn't that CFQ should make sure all ...
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2answers
850 views

order 4 allocation failure disaster

Some environment details first: Hardware: Intel Server Board S2600GZ 2 x Intel Xeon CPU E5-2620 64GB DDR3 RAM Intel RAID Controller RS2BL (LSI SAS2108) with 4TB LVM Volume made of SAS disks Software:...
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1answer
3k views

web server “task blocked for more than 120 seconds”

my web server is down every 2 days. it became unresponsive and I can only see the message below on the console. task **** blocked for more than 120 seconds. The only way to bring it up is resetting ...
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96 views

CentOS 5.10 TCP Sequence Number

We have done a security check on a server and its come back with Linux Kernel TCP Sequence Number Generation Security Weakness. We are looking to correct this being flagged up on the check We are ...
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2answers
4k views

Linux NFS hangs after about 15 minutes

I'm somewhat new when it comes to administering Linux and NFS, so please bear with me. We are trying to setup a small cluster at work. Currently the system is just 2 DELL high-end workstations, ...
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296 views

Can high disk cache usage lead to external fragmentation and ultimately to page allocation failures?

We're getting page allocation failures on a Linux server (3.2 kernel). We've been told the problem is directly related to the high use of the memory for cache; this would lead to external ...
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2answers
495 views

All terminal windows suddenly disappear in Linux [closed]

Sorry in advance for the wall of text. I'm having a problem which is leaving me with very few clues as to what might be going on. Also, I apologize if ServerFault isn't the ideal place for this ...
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1answer
439 views

WANem doesn't boot after install

I'm using WANem live cd (based on knoppix) to perform network bandwidth tests. In order to keep the current configuration, I've installed it on hard disk (using the gui installation tool provided ...
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1answer
270 views

CVE-2014-0196 Vulnerability for CentOS

Trying to patch CVE-2014-0196 Vulnerability but yum can't find packages updates CentOS 6.5 (Final) Panel version: 11.0.9 Update #61 # uname -r 2.6.32-358.11.1.el6.x86_64 # yum update kernel Loaded ...
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3answers
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ext3/ext4 physical block size view

I'm using a suse 11 server with xfs and using "xfs_info /srv" command i seen this. xfs_info /srv/ meta-data=/dev/mapper/vg01-srvvol isize=256 agcount=38, agsize=1964032 blks = ...
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2answers
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Server won't boot, kernel panic - not syncing

After a reboot of a CentOS 6.2 server we are getting a kernel panic with the following error: Kernel panic - not syncing: Attempted to kill init! Panic occurred, switching back to text console ...
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1answer
193 views

“sock_sendmsg-error 22” error in RHEL

I am using RHEL 5.10 servers ( which are in cluster using some shared services). When I restart them using "init 6" or "reboot". the servers hang while shutting down, continuously showing the below ...
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1answer
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Linode Kernel Headers

I am trying to install the Idera (R1soft) linux agent on a Linode running Ubuntu 12.04LTS. The agent requires a driver which in turn requires the kernel headers. Linode uses custom kernels though so ...
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3answers
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Why does /proc/net/tcp6 represents ::1 as ::100:0

I was writing an utility to check /proc/net/tcp and tcp6 for active connections as its faster than parsing netstat output. As I dont actually have ipv6 enabled I was mainly utilizing localhost as my ...
4
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1answer
217 views

how to determine who is using the slabs?

Is there any way to figure out who or what is allocating size-256 slabs, like in the slabtop output below? I had to reboot a server yesterday that had 5G out of 8G RAM in size-256 slabs and was ...
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30 views

Linux meminfo “Buffers” takes more than 10% total memory? [duplicate]

I noticed that meminfo - Buffers occupies significant amount of RAM on some servers in my work environment. I'd like to know what is exactly is "Buffers" and why it takes that much amount of RAM. ...
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1answer
2k views

“show_signal_msg: N callbacks suppressed” then pegged at 100% and machine unresponsive

This happened on an Ubuntu 14.04 64-bit DigitalOcean Droplet: Apr 22 02:17:02 localhost CRON[32514]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Apr 22 03:16:59 localhost ...
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795 views

Removeing ulimit from boot / init

In CentOs as from version 6 there is a by default process limit 1024 for every user i.e /etc/security/limits.d/90-nproc.conf * soft nproc 1024 I have to execute a backend service/...
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1answer
185 views

How can I make my own linux distro? [closed]

My question is bit off-topic or may be impractical. The thing is, on the web too many material available to download customized linux distro. But what if I want to make my own linux distro ? Lets ...
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2answers
6k views

Can't update linux kernel on VPS

I recently started using VPS from OVH: http://www.ovh.co.uk/vps/vps-classic.xml This is likely problem very specific to this one provider. My goal is to install and run Docker on it, for this I need ...
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1answer
599 views

What signal is being sent to an EC2 Instance on shut down?

When you terminate an instance-store pv instance through the AWS console or the API, what "signal" does it receive so it knows it has to gracefully shut down? First guess would be ACPI, but on boot ...
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786 views

Server crash : “unable to handle kernel paging request”

My fresh new Ubuntu webserver randomly crashes with the following error in the syslog. It doesn't respond anymore and I have to do a hard reboot. It happens almost one time a day. Server kernel is : ...
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150 views

__ticket_spinlock high cpu

We are having a strange problem on our Ubuntu 10.04 KVM infrastructure, where periodically, one of two vm webservers freaks out, with persistently high load, even if we restart the applications. (the ...
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1answer
164 views

What is the latest stable valid linux kernel for 3.8 version? [closed]

I want to know the latest stable kernel version of 3.8. Can any one help me out for this issue? I browsed for this issue but I didnt get the solution
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1answer
2k views

CIFS error -512 on a mount

So we have Alfresco running at work and I like to have our repository mounted via CIFS: mount /mnt/alfresco/ -v mount.cifs kernel mount options: ip=192.168.8.91,unc=\\alfresco.example.com\alfresco,...
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2answers
100 views

Virtual Machines - Possible to Restore Replace Kernel without Rebuild?

I'm using Linux Virtual Machines (Wheezy, Linux Vserver), each with a desktop environment including Firefox. If a Virtual Machine where to be compromised (e.g., SQL injection) so the kernel is ...
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1answer
2k views

How to undo rm -rf? [closed]

How we can undo rm -rf command ? For example, I have Application folder. And I have remove it by rm -rf Application But it was my mistake and want to recovery or want that Application Folder. But ...
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1answer
206 views

ext4 production ready on kernel 2.6.32 (debian6)?

I've to maintain a production system on debian6 (kernel version 2.6.32). I'd like to use ext4 on a ssd disk (and generally hope to improve performance upgrading from ext3). I can't find any reference ...
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1answer
5k views

Linux Kernel complaining about TSC when selected clock source is Hyper V

We are running RHEL 6 boxes on HyperV with Windows Server 2012. On a few on our RHEL boxes, I am seeing this error in /var/log/messages kernel: Clocksource tsc unstable (delta = -62519781 ns). ...
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1answer
1k views

Linux Cannot change tx-checksumming

On a Linux 3.2 kernel: Linux 3.2.0-4-686-pae #1 SMP Debian 3.2.46-1+deb7u1 i686 GNU/Linux on VmWare, i get checksum errors on ipv6 tcp packets. So I can ping6, but not connect by ipv6 to ssh, smtp, ...
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296 views

Make a bridge with two ports behave like a veth pair

I have a linux bridge with two ports, namely p0 and p1, and I would like to modify the bridge behavior so that every frame showing up in one port is relayed to the other port and viceversa, i.e. the ...
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66 views

find out which memory pages are owned by kernel

I can obtain a wonderful memory map of all processes with the Linux command pmap $(ps -A | awk '{print $1}'|grep -v PID) | sort | grep \^0 It looks like ... 00007fd6dbf45000 4K rw--- /lib/...
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247 views

ext3 option on error doesn't work

I have a redhat server 5.8 with ext3 on top of lvm, i noticed ext3 has setting "Errors behavior: Continue" in the fs super block, from the man page of mount command i readed this errors=...
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2answers
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Linux: echo 3 > /proc/sys/vm/drop_caches takes hours to complete

I have a Thecus N8900 NAS, which is a Linux based file server, providing files via NFS to six clients. For some reason that Thecus support has yet to explain, it runs a script that checks /proc/...
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1answer
388 views

esxi 5 VMKernel and linux driver compatability mode [closed]

Many peoples around the web say, the esxi 5 kernel isn't based on linux kernel, but in the same times they say "ESX(i) includes a Linux driver compatability mode (drivers still have to be compiled ...
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1answer
653 views

12.04 Migration Process time delay

We have an issue in our server that is the migration process in taking time and also the load in the server is getting high due to that. No LSB modules are available. Distributor ID: Ubuntu ...
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2answers
789 views

Linux kernel detecting wrong processor frequency

After a cold boot of a 6.0.8 Debian server (HP ProLiant), ntpd played havoc with system time: offset and jitter with respect to the usual and reliable reference time servers growing without limit. (...