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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120 views

Performance impact of running kdump

We are currently running into an issue on a RHEL 5.6 server. The server randomly becomes unstable, kernel wait messages are showing up in /var/log/messages, and we've now had it reboot twice. We've ...
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1answer
218 views

linux + from where uname -r take the linux version information

when I type the uname -r command on linux: uname -r I get the following info: 2.6.18-274.7.1.el5PAE my question from which file uname -r read this info , or from where uname -r read the Data ? ...
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1answer
127 views

Linux initramfs read-only

In a Linux system consisting of a bootloader, the kernel and an initramfs (no block devices, no other root filesystem): Is it possible to make the initramfs read-only once expanded into memory?
3
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1answer
711 views

AppArmor - root: “You do not have enough privilege to read the profile set.”

I'm trying to use AppArmor on a remote hosted Xen server with a custom built kernel. AppArmor appears to be running, but not correctly. For example if I run the following command as root: # ...
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2answers
285 views

random server reboots [closed]

Jan 6 22:43:27 HOSTkernel: [34400.406538] Firewall: *Port Flood* IN=eth0 OUT= MAC=00:25:90:33:2c:d4:00:12:7f:34:7d:bf:08:00 SRC=141.0.9.77 DST=SERVER IP LEN=60 TOS=0x00 PREC=0x00 TTL=59 ID=2055 DF ...
2
votes
1answer
845 views

Still getting aacraid: Host adapter abort request errors after following recommended steps

I am getting the infamous aacraid: Host adapter abort request error with my new Adaptec RAID Controller under high I/O. I have read several forums, even Adaptecs, that setting the ...
2
votes
1answer
198 views

/proc/<pid>/stat children CPU time

I've been running the following command on my linux box: watch -d -n 1 "cat /proc/19866/stat" The pid above is a pid of Nginx's master process - I would expect the following fields to be changing: ...
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1answer
389 views

PPTPd - configuration error?

an 5 01:09:12 vpn pptpd[1832]: GRE: read(fd=6,buffer=611860,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check option syntax ...
2
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1answer
84 views

at what level modprobe operates ? - linux

I have a machine with Ubuntu 12.04 64 bit, i have the need for blacklisting a module, i have blacklisted it in blacklist.conf but nothing happened; i have solved my problem passing ...
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2answers
391 views

Server freezes and suddenly load going very high

I'm on CentOS 5.7 and I get server freezes quite a lot and the logs show the following output: Dec 26 18:33:51 server kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this ...
3
votes
1answer
1k views

HPET missing from available clocksources on CentOS

I am having trouble using HPET on my physical machine. It is not available, even though I have enabled it in my bios, forced it in grub, and triple checked my kernel to include HPET in its ...
2
votes
2answers
1k views

Tune Linux kernel against SYN flood attack

I have read an article (not in English) on how to protect a server against SYN flood attacks by modifying some directives in sysctl.conf. That article has a sentence like: "it's possible to recompile ...
2
votes
1answer
253 views

overriding default scheduler for blkio requests in cgroups

I am trying to optimize a set of servers that have to reside on single machine. i.e. i can have multiple application server, a DB server and of course a samba server as well in same instance. Now I ...
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2answers
174 views

With the kernel compiled by myself, when install VMware modules, it prompts Kernel headers not found

With the kernel compiled by myself, when install VMware modules, it prompts Kernel headers not found. My kernel source code is here: /root/kernel/linux-3.7 Where is the kernel headers?
3
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1answer
2k views

Why OOM-killer invoked even when huge amount of RAM is free

On EC2 ebs-backed xlarge ubuntu instance, oom-killer is getting invoked. From /var/log/syslog output below, it appears that ZONE_NORMAL is running out of memory: Node 0 Normal free:11344kB ...
3
votes
4answers
629 views

Server randomly freezes

Im facing a very strange issue, my debian squeeze freezes up always at night (Berlin, time). Here is what i get from a time and after doing this a few times, it becomes frozen and must be hard-reset. ...
0
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1answer
2k views

end_request: I/O error, dev sda, sector xxxxxxxxx

I have a IBM server. This server contains 3 hard disk with RAID 5. It was working fine earlier. Unfortunately this machine got the following error message. After that I have rebooted the systems. ...
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4answers
16k views

In CentOS 6.x, how can I upgrade to Kernel 3.4?

I have a server with CentOS 6.2 with kernel version 2.6.32, but I need to increase my application Performance. The Kernel Version 3.4 has x32abi which can improve the performance so i want to upgrade ...
1
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3answers
663 views

Ext4 kernel panic

I'm getting such kernel panics: EXT4-fs error (device md2): ext4_ext_find_extent: bad header/extent in inode #97911179: invalid magic - magic 5f69, entries 28769, max 26988(0), depth 24939(0) ...
0
votes
1answer
175 views

How to log kernel panics without KVM

My server is crashing and I can't find an answer why. It all started after my datacenter upgrade RAM from 16 GB to 32 GB. I also found such logs in dmesg - they've started to show itself just before ...
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2answers
330 views

What does the FreeBSD kernel message “vnode_pager_putpages: I/O error 5” mean?

Our FreeNAS file server's /var/log/messages and dmesg logs are filling up with: Nov 28 14:50:00 chef kernel: vnode_pager_putpages: I/O error 5 Nov 28 14:50:00 chef kernel: vnode_pager_putpages: ...
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1answer
181 views

Which will give more free RAM to linux? [closed]

Trying to avoid some issues so I've been trying to learn vm. in kernel tuning but still a little confused even after googling. The lower background_ratio is the sooner the flushes? the lower ...
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1answer
663 views

drivers/rtc/hctosys.c: unable to open rtc device (rtc0) after recompile on boot

After recompiling a new kernel on CentOS 6.3, using the same kernel I have been using on several other machines, I am getting a kernel panic on two machines. I get the following when trying to boot: ...
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1answer
293 views

Realtek R8168 network driver 8.034.00 not compiling under CentOS 5.8 64-bit [closed]

I'm trying to compile Realtek R8168 driver 8.034.00 on CentOS 5.8 64-bit and I got this: make -C /lib/modules/2.6.18-308.16.1.el5/build SUBDIRS=/r8168-8.034.00/src clean make[1]: Wejście do ...
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1answer
130 views

EC2 kernel decision and issues with creating a new machine with my AMI

I could really use some advice. I started a new instance on EC2 using Amazon's AMI and during the deployment process I selected a Kernel ID of "Use Default". I then configured my server the way that ...
1
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3answers
710 views

“postgres blocked for more than 120 seconds” - is my db still consistent?

I am using an iscsi volume on an Open-E storage system for several virtual machines running on a XenServer host. Occasionally, when there is a very high disk I/O load on the virtual machines (and ...
0
votes
1answer
415 views

Issue with kernel boot [OVH SERVER]

Trying to install OpenVZ kernel on Centos 6.3, Yes my kernel is installed i can see it in the /boot folder, yes it is Rhel6 and yes it is all up to date, i checked this with yum update. My issue ...
1
vote
2answers
926 views

FreeBSD Listen Queue Overflows - can't increase max queue size

I have a decently high trafficked FreeBSD Nginx server, and I'm starting to get a large number of listen queue overflows: [root@svr ~]# netstat -sp tcp | fgrep listen 80361931 listen queue overflows ...
1
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2answers
307 views

Refresh /dev/sdx list

I've been messing around with my storage array (in that case 2xMD3000 SAS) and between the scans/rescans/delete/add my /dev/sdx block devices are all messed up. Some of them are non existent and using ...
2
votes
1answer
365 views

Linux Kernel IRQ Routing with irqbalance / kernel options

I'm trying to get my Xen Dom0 distributing the irqs in an smp enviroment. As far as I know there are 2 Options: Use irqbalance Configure the kernel without cpu hotplug support My System is Debian ...
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0answers
162 views

what does setting kernel.shmall too high do?

I'd like to know what the kernel does when the value of kernel.shmall works out to being larger than the total amount of available memory (main memory + swap space). Is the value ignored and the ...
1
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1answer
344 views

yum update kernel without removing old?

When I yum update it wants to remove the oldest of the 3 kernel I have and upgrade to a new. Is it possible to get yum not to remove old kernels?
2
votes
1answer
948 views

Scientific Linux won't boot after yum updates kernel

I just updated kernel for my Linux: [root@localhost ~]# cat /etc/redhat-release Scientific Linux release 6.1 (Carbon) [root@localhost ~]# uname -a Linux localhost.localdomain ...
1
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2answers
417 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 ...
1
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1answer
3k 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 ...
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votes
2answers
203 views

server not working smoothly [closed]

Hi I am getting this error message in log. Please suggest something to fix this issue Sep 6 06:19:17 sa1 kernel: sd 0:0:0:0: SCSI error: return code = 0x08000002 Sep 6 06:19:17 sa1 kernel: sda: ...
1
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1answer
127 views

ip_conntrack ideal or not for server stability

By default the module ip_conntrack is installed into the kernel. My question is simple, is having ip_conntrack a performance booster for better tracking of connections? On VPS nodes they do not have ...
4
votes
1answer
347 views

Disabling/Enabling Modules Parameter RHEL

I'm working with kernel module parameters, and I've found myself a bit confused. In particular, I'm attempting to enable posix ACL support for XFS file systems. This requires the XFS module to be ...
2
votes
2answers
2k views

How to update from RHEL6.1 to RHEL6.2 ,not RHEL6.3

Now I'm using RHEL version 6.1, and would like to update to 6.2. If I use the command , yum update the OS version become 6.3. so I used the command below yum install kernel-2.6.32-220.23.1.el6 ...
0
votes
0answers
523 views

XEN Domain crash - kernel panic

I have a server with CentOS 5.8.Final, running the 2.6.18-308.4.1.el5xen kernel. I installed the Virtualizorpanel 2 months ago and my VPS are OK, but yesterday one of my VPS crashed. I changed theRAM ...
2
votes
1answer
162 views

What is the best way to get kernel 3.2 on Debian 6?

I'm using Hyper-V as hypervisor and there is a need to use Debian 6 in production on it, but as I know it's not supported. I want to use kernel 3.2 with integrated linux integration components. What ...
0
votes
1answer
381 views

Hotplug area too small error

I have VM running under RHEL6, which is running under HyperV. It has a lot of important soft installed, but does not have suffocating workload (~10% CPU is used). It's been really unstable recently ...
1
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1answer
3k views

Windows Server 2008 R2 Kernelbase.dll exceptions

Hi we have a Windows Server 2008 R2 server that has been having issues lately. Right at the same time as most of the issues started happening I noticed that there are lots of exceptions in the logs ...
0
votes
1answer
2k views

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

Sorry about the formatting below... 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 ...
0
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2answers
665 views

systemtap not initializing correctly on Ubuntu 12 (Precise)

I work at a firm with a certain amount of legacy batch-processes. Some of that stuff is really leaky when it comes to database connections. I need to log every process in the system, which opens a ...
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1answer
284 views

ubuntu 12.04 server comes with Odd Kernel Development version.How can it be upgraded??

I have downloaded latest ubuntu server edition but after installing its showing kernel of 3.2.0-23 Generic kernel,which is a development version. So how can i change to stable release with out ...
0
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2answers
270 views

What is the difference between -generic and -virtual kernels?

I am using XEN server 6.0 on machine and I want to install ubuntu 12.04 64bit. I want to optimize OS for running as VM. I choose to install from "http://archive.ubuntu.net/ubuntu/" but its showing ...
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1answer
127 views

How to package a custom kernel for Debian?

I've build a custom linux kernel from the vanilla source tree using the deb-pkg target: make deb-pkg After that package has been built I've got several .deb files. However I'd like to upload those ...
0
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1answer
1k 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
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1answer
315 views

Kernel will not upgrade after installing linux-image on Debian

I am attempting to upgrade my Linux kernel to 3.2 on my Debian server. I have installed the image package, but even after rebooting I still seem to have my old 2.6 kernel. I am assuming I probably ...