RAMDISK: incomplete write, kernel panic on centos

Today from early morning I was called by my colleague who said that his centos6 box can’t boot after reboot. After grub screen centos show that error:

RAMDISK: incomplete write (6257 != 32768)
write error
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
Pid: 1, comm: swapper not tainted %kernel_ver% #1
Call trace:

Let fix that.

Continue reading “RAMDISK: incomplete write, kernel panic on centos”

About root mail

Ok. After fresh install of centos I usually make two commands first

yum remove posftix sendmail
yum install ssmtp

So I just understand that root (and other users mail) I never receive! Lets fix it. Open /etc/aliases with you favorite nano and scroll to the bottom of the file

# Person who should get root's mail
root:           your@serviceemail.com


After that lets test

echo "test message" | mail root

Check your@serviceemail.com. Thats all!

Installing Kernel 5.X with Google BBR support in centos7 box

Install elrepo & new kernel

rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
rpm -Uvh http://elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
yum --enablerepo=elrepo-kernel install kernel-ml -y

Lets understand in which position our new kernel installs. Rows begins with 0, so if you see new kernel on the top you should choose grub-set-default 0

egrep ^menuentry /etc/grub2.cfg | cut -f 2 -d \'
grub2-set-default 0
reboot
Continue reading “Installing Kernel 5.X with Google BBR support in centos7 box”