If you plan to take the RHCSA 6 or RHCE 6 exams, you’ve got to hurry because these exams will be withdrawn in two to three weeks.

As RHCSA 7 is not too different from RHCSA 6, it will not be too painful if you miss the date.

It’s going to be an other song if you wanted to take the RHCE 6 exam, because the v7 is an other world: you will have to start almost from scratch! Firstly, it’s now 3.5 hours instead of 2. Secondly, topics are different: network (teaming, bonding, ipv6, etc), Kerberos (NFS+Samba), security (firewalld), storage (iSCSI), and database (MariaDB).

If you thought about taking the RHCE 6 exam, book it now and work hard to pass it at the first attempt!

Since RHEL 6, a transaction history has been added to the yum command.
This feature allows you to precisely know which packages have been installed on a server and in which order.
In addition, you can undo or redo any of the previous package installations.
Finally, by comparing the rpmdb version of two servers, you can verify if the exact same packages have been installed on both of them, which can be useful when moving from development to production environments.
To get into the details, check the tutorial about using the yum transaction history.

If you need to configure a server for a specific task (for SAP, with reduced network latency, for maximum throughput, as a desktop, as a virtual host, etc), a dedicated tool already existed in RHEL 6: tuned-adm.

This tool still exists in RHEL 7 and in an enhanced version. If you want to know more, a dedicated tutorial on tuned-adm is now available.

In one of his latest videos Sander van Vugt shows us that some SELinux information is not available without some tricky operations.

Actually, after a standard RHEL 7 / CentOS 7 installation, only basic SELinux man pages are installed. All the SELinux man pages dealing with applications (httpd, vsftpd, etc) need an additional work to be accessible.

Now, you’ve got two options: watch Sander van Vugt’s video or access my dedicated tutorial about deploying additional SELinux man pages. It’s up to you!

Yesterday, Red Hat announced the official release of RHEL 6.6.

This minor version brings several improvements:

• The scap-security-guide package has been added providing a convenient and reliable way to verify system compliance on a regular basis,
• The KeepAlived and HAProxy packages are now fully supported,
• The System Security Services Daemon (SSSD) package has been updated to make Linux-Windows integration easier: you can now enable a cross-realm Kerberos trust through a RHEL 7 server,
• The Performance Co-Pilot (PCP) framework for performance monitoring and management has been added: you can now monitor performance across a set of RHEL 6 and 7 servers in a single, consistent approach,
• The OpenJDK 8 is now available as a technology preview,
• Various performance improvements coming from RHEL 7 have been also backported.

Sources: Red Hat 6.6 Release Notes and Red Hat 6.6 Technical Notes.

Today, Scientific Linux 7.0 is officially released.

In the Scientific Linux 7.0 release notes, two points need attention:

• The default Scientific Linux 7 installation provides automatic updates via the yum-cron package: because this distribution is often installed by graduate students, it has been decided to reduce the security risks for a novice by applying security updates automatically each night.
• There is no supported upgrade path from Scientific Linux 6 to Scientific Linux 7: it is a deliberate choice not to take any risk of leaving the system in an intermediate state.

You can download the Scientific Linux 7.0 distribution from now on.

Today, Dell just released its KVM Virtualization made easy for RHEL 7.
To anybody interested in building a KVM lab, this is a must-read.

In this white paper, Jose De la Rosa from Dell explains all the steps involved in this operation:

• required packages,
• required services,
• networking configuration (with or without bridge),
• VM image location,
• VM creation & cloning,
• basic and advanced VM management.

Happy reading!

The I/O scheduler policy has changed with Red Hat Enterprise Linux 7.

The default I/O Scheduler is now CFQ for SATA drives and Deadline for everything else.
Indeed, for faster storage than SATA drives, Deadline outperforms CFQ, giving a performance increase without any special tuning.

Additional information and instructions are available in the I/O scheduler tutorial.

The Red Hat certification team recently made some adjustments to the RHCSA & RHCE exams objectives for RHEL 7.

Concerning the RHCSA exam, VNC and LUKS related tasks have been removed, when firewall settings can now be set up through iptables or firewalld, which is very sensible. The client LDAP configuration, although no longer directly specified, seems to remain an objective through the client configuration to an authentication service.
This appears to be a slight adjustment with very limited consequences.

Concerning the RHCE exam, access to Samba shares through Kerberos authentication has been added when Rsyslog client & server configurations have been removed.
Two easy tasks have been replaced with a complicated one, emphasizing again the weight of Kerberos.
A RHCE 7 candidate will definitely need serious Kerberos skills! At least, it’s what Red Hat people want.