Linux Redhat 7: How to clear boot directory


Recently I noticed that multiple Vmware Linux templates had /boot filesystem used more than 90%
If you look on the web u will find a lot of solutions based just on removing kernel rpms. I disagree !
I began to clear the /boot directory removing the oldest kernels but this was not enough.

At this point you must go to /boot directory and look for rescue files:

# ls | grep rescue

initramfs-0-rescue-b20d7fe5b15140269ad2c2e51af4735e.img

vmlinuz-0-rescue-b20d7fe5b15140269ad2c2e51af4735e

initramfs-0-rescue-80405299bcbc4ebabf5827a44c193.img

vmlinuz-0-rescue-80405299bcbc4ebabf5827a44c193

initramfs-0-rescue-d58aadc169974f0ea93d637c046d764b.img

vmlinuz-0-rescue-d58aadc169974f0ea93d637c046d764b

Each rescue file does not belong to any rpm package, so you can manually delete the oldest pair files. In order I suggest you to follow this actions:

1) Look for a single rescue pair. If you want to know which kernel does belong to, you can run lsinitrd initram-0-rescue-
2) Try to boot the system using the rescue from the previous point
3) If everything worked fine, you can boot with the latest kernel and delete each old pairs rescue files.
4) Lastly, update the GRUB2 configuration:  grub2-mkconfig -o /boot/grub2/grub.cfg

Thank to Paolo Fruci and Marco Simonetti for helping me dealing with this issue, we played together 🙂

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Linux Redhat 6.10 released!!


Two days ago RHEL 6.10 was officially released.
Reading from the web I see new interesting features:

“This release also includes a Red Hat Enterprise Linux 6.10 base image
to help enterprises more easily migrate Red Hat Enterprise Linux 6
workloads into container-based applications. These cloud-native
workloads can then be deployed and maintained on a more modern
platform, including Red Hat Enterprise Linux 7, Red Hat Enterprise
Linux Atomic Host, and Red Hat OpenShift Container Platform.

To make it easier for customers to plan their migration to Red Hat
Enterprise Linux 7, Red Hat Enterprise Linux 6.10 provides updates to
the Pre-upgrade Assistant, Red Hat Upgrade Tool, and the accompanying
documentation. Learn more about the upgrade process and how to access”

I never migrated before a major RHEL release, can’t wait to play with 🙂

Got Certified!!!


I passed the exam Redhat EX318!
Now I’m certified on RHEV as “RHCVA” – Redhat Certified Virtualization Administrator.
I have to thank a couple of friends: Giovanni Mancuso and Davide Giannlivigni, they helped me studying for the exam ( I did not take the course )

Thank you both!!!
😀

Redhat: How can I check virtualization prerequisites?


Playing with virt commands, I found virt-host-validate .

It is very useful! If I run it from a virtual machine without nested virtualization enabled, I will have:

# virt-host-validate
QEMU: Checking for hardware virtualization : FAIL (Only emulated CPUs are available, performance will be significantly limited)
QEMU: Checking if device /dev/vhost-net exists : PASS
QEMU: Checking if device /dev/net/tun exists : PASS
QEMU: Checking for cgroup ‘memory’ controller support : PASS
QEMU: Checking for cgroup ‘memory’ controller mount-point : PASS
QEMU: Checking for cgroup ‘cpu’ controller support : PASS
QEMU: Checking for cgroup ‘cpu’ controller mount-point : PASS
QEMU: Checking for cgroup ‘cpuacct’ controller support : PASS
QEMU: Checking for cgroup ‘cpuacct’ controller mount-point : PASS
QEMU: Checking for cgroup ‘cpuset’ controller support : PASS
QEMU: Checking for cgroup ‘cpuset’ controller mount-point : PASS
QEMU: Checking for cgroup ‘devices’ controller support : PASS
QEMU: Checking for cgroup ‘devices’ controller mount-point : PASS
QEMU: Checking for cgroup ‘blkio’ controller support : PASS
QEMU: Checking for cgroup ‘blkio’ controller mount-point : PASS
QEMU: Checking for device assignment IOMMU support : WARN (Unknown if this platform has IOMMU support)
LXC: Checking for Linux >= 2.6.26 : PASS
LXC: Checking for namespace ipc : PASS
LXC: Checking for namespace mnt : PASS
LXC: Checking for namespace pid : PASS
LXC: Checking for namespace uts : PASS
LXC: Checking for namespace net : PASS
LXC: Checking for namespace user : PASS
LXC: Checking for cgroup ‘memory’ controller support : PASS
LXC: Checking for cgroup ‘memory’ controller mount-point : PASS
LXC: Checking for cgroup ‘cpu’ controller support : PASS
LXC: Checking for cgroup ‘cpu’ controller mount-point : PASS
LXC: Checking for cgroup ‘cpuacct’ controller support : PASS
LXC: Checking for cgroup ‘cpuacct’ controller mount-point : PASS
LXC: Checking for cgroup ‘cpuset’ controller support : PASS
LXC: Checking for cgroup ‘cpuset’ controller mount-point : PASS
LXC: Checking for cgroup ‘devices’ controller support : PASS
LXC: Checking for cgroup ‘devices’ controller mount-point : PASS
LXC: Checking for cgroup ‘blkio’ controller support : PASS
LXC: Checking for cgroup ‘blkio’ controller mount-point : PASS

Opensource day 2016!!


Yesterday I have been with colleagues at OpenSource Day in Rome!
It was first time for me and I was so funny following Redhat Speech, Labs and much more.
I also saw old and ex colleagues.
I took some picture:

Rome, Palazzo dei congressi

Me

Colleagues

Openbaton 2 Installation


Today I installed with a collegue a basic openbaton environment on a Ubuntu 16 server. Customer needs an NFV ETSI Orchestration environment. I began the task installing and configuring the basic modules, it was very easy and funny!

This is the dashboard 🙂

LPIC remote labs


I’m working on funny idea: looking on the web I read that a lot of people need linux systems to study for LPIC-1 exam. I want to make Centos and Ubuntu remote avaiable systems with a very very low price for the rent! With this method , each one can play and test LPIC-1 topics without have a full computer.
You just need a putty client or web browser , so even a tablet is enough 😉