Review: RHEL 7 lands with a jolt
There's a lot to like in the next Red Hat Enterprise Linux, but some fundamental changes may prove problematicFollow @pvenezia
One of the hallmarks of Red Hat Enterprise Linux is that it overwhelmingly favors stability over currency. As such, RHEL generally ships with packages and frameworks that are years behind the current releases. This is by design, to ensure that the RHEL distribution is as solid as possible. As an example, Red Hat's slow and steady approach saved RHEL 6.4 users from the OpenSSL Heartbleed vulnerability because all RHEL versions up to and including that version shipped with a two-year-old version of OpenSSL that was not affected.
If you follow the Fedora distribution, which serves as the icebreaker for the more stable RHEL distribution, you've seen many changes coming down the pike for RHEL 7. Many of these changes are the most fundamental we've seen in quite some time. Several are to be heralded, but others -- notably the replacement of Init and Upstart with Systemd -- are likely to chafe longtime RHEL users and potentially curb adoption.
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What's new in RHEL 7
There is a long list of changes in RHEL 7, but only a few are fundamental. RHEL 7 now uses Systemd rather than Init scripts for service startup and management -- more on that later. The new default file system is XFS rather than Ext4, with support of XFS file systems up to 500TB in size. To that end, RHEL 7 now supports Ext4 file systems as large as 50TB.
Linux containers get a front-row seat in the form of Docker. RHEL can now perform cross-domain trusts with Microsoft Active Directory, so users can authenticate to Linux resources with Active Directory accounts without the need for synchronization.
RHEL 7 also includes new monitoring and performance tools. For instance, the Performance Co-Pilot (PCP) provides a new API for importing, exporting, and processing performance data, while the Tuned daemon provides dynamic system performance tuning.
On the inside, RHEL 7 incorporates enhanced NUMA affinity features that optimize performance on a per-process level by aligning processor affinity to RAM location, reducing cross-node communication and improving process performance.
RHEL 7 offers tighter integration with the VMware vSphere hypervisor via 3D graphics drivers for hardware acceleration with OpenGL and X11, and Open Virtual Machine Tools, an open source implementation of VMware Tools that is now a maintained package.
Open Linux Management Infrastructure (OpenLMI) is now supported. OpenLMI is a framework that allows for common configuration, management, and monitoring of hardware and software through a remote connection. It provides a standard API that can be used by any compliant controller to make changes to the server configuration or to monitor the system.