Proper way: after kernel update [xen]

Kernel Diary: this just to remind me proper steps to do after dom-0 kernel updates

1. log in into each dom-U and run

#yum update -y

this will update kernel devel and kernel headers on dom-U

failing to do this will make iptables not able to start

2. fix xen kernel script

this will update latest kernel on dom-U (do this on every dom-U before rebooting them!!)

# /script/fixxenkernel

http://blog.apis17.info/2011/01/fix-xen-kernel.html

3. xm list

this will list all dom-U

4. xm reboot

this will reboot dom-U server. or just reboot entire system.

if you have iptables problem after dom-U reboot please install kernel-headers

#yum -y install kernel-devel kernel-headers

iptables: Table does not exist (do you need to insmod?)

then,

#modprobe ip_tables

hope this will save some time to figure up why iptables not working.

remember: i'm using hypervm. fixxenkernel scripts only available on hypervm

iptables after kernel updates [ solved ]

i have this

can't initialize iptables table `filter': Table does not exist (do you need to insmod?) Perhaps iptables or your kernel needs to be upgraded.

to fix this problem

#yum update

Dependencies Resolved

================================================================================

Package Arch Version Repository Size

================================================================================

Installing:

kernel-xen i686 2.6.18-238.19.1.el5 updates 18 M

kernel-xen-devel i686 2.6.18-238.19.1.el5 updates 5.5 M

Updating:

curl i386 7.15.5-9.el5_6.3 updates 233 k

kernel-headers i386 2.6.18-238.19.1.el5 updates 1.1 M

Transaction Summary

================================================================================

Install 2 Package(s)

Upgrade 2 Package(s)

done..

:)

nat disabled after kernel update (xen)

Iptables problem

Trying to start iptables gives :

iptables v1.3.5: can't initialize iptables table `filter': iptables who? (do you need to insmod?)

Perhaps iptables or your kernel needs to be upgraded.

Trying to “modprobe iptables” also gives an error message :

FATAL: Could not load /lib/modules/2.6.18-53.1.6.el5xen/modules.dep: No such file or directory

Here what I did to fix the problem:

• yum install kernel-xen kernel-xen-devel
• /sbin/depmod

After that, /sbin/iptables -L now works correctly!

ref: http://blog.jphoude.qc.ca/2007/11/17/xen-troubleshooting-centos-5/

found reference for openvz: http://thelinuxnoob.com/linux/enable-nat-module-for-vps-can%E2%80%99t-initialize-iptables-table-nat%E2%80%99-table-does-not-exist/

rebuild xen dom-u kernel

symtom: after dom-0 reboot, all dom-u not in latest kernel. to fix this,

cd /usr/local/lxlabs/hypervm/httpdocs/

lphp.exe ../bin/misc/fixcentos5xen.php

http://markus.revti.com/2010/08/hypervm-xen-installation/

clean up disk space

today i delete previous kernel files. this freed up about 200MB :)

[root@local html]# df -h

Filesystem Size Used Avail Use% Mounted on

/dev/hdb6 8.6G 7.9G 250M 97% /

i'm using this reference:

http://www.cyberciti.biz/faq/proper-way-to-remove-old-linux-kernels/

reboot kernel only once

http://www.brianessig.com/2009/09/grub-reboot-to-new-kernel-once/

Source : IWH senior suport

xen with PAE kernel

ayoyo..

cat /proc/meminfo

MemTotal: 2207744 kB

MemFree: 1227388 kB

it is4GB

http://www.howtoforge.com/make-your-xen-pae-kernel-work-with-more-than-4gb-ram-debian-etch-grub

will be updated later

forward NAT rules

http://www.linuxtopia.org/online_books/centos_linux_guides/centos_linux_security_guide/s1-firewall-ipt-fwd.html

By default, the IPv4 policy in Red Hat Enterprise Linux kernels disables support for IP forwarding, which prevents boxes running Red Hat Enterprise Linux from functioning as dedicated edge routers. To enable IP forwarding, run the following command:

sysctl -w net.ipv4.ip_forward=1

reboot on kernel panic

http://www.techrepublic.com/blog/opensource/auto-reboot-linux-after-a-kernel-panic/158

credits to iwh unknown senior support

check processor vt support

http://www.cyberciti.biz/faq/linux-xen-vmware-kvm-intel-vt-amd-v-support/

egrep ‘(vmx|svm)’ /proc/cpuinfo

this will show AMD or Intel VT support if available

update: http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/

the error:

Alert: Could Not Start Vps, Reason: Error: HVM guest support is unavailable: is VT/AMD-V supported by your CPU and enabled in your BIOS?:

for intel

# grep --color vmx /proc/cpuinfo

for amd

grep --color svm /proc/cpuinfo

finally

cat /sys/hypervisor/properties/capabilities

fix xen kernel

this problem happened when i try to use latest version of xen kernel in hypervm
the error code:

Error: (2, 'Invalid kernel', 'xc_dom_parse_elf_kernel: ELF image has no shstrtab\n')

windows vps running ok but linux cannot start.

search thru google and found; http://www.webhostingtalk.com/archive/index.php/t-761158.html

run this script using root:
# /script/fixxenkernel

then done! linux xen client successfully start. - END -