Pros: RHEL 5.7 is mostly about hardware compatibility and performance enhancements,as well as the new subscription service.
Cons: A number of interesting RHEL 6 features didn’t get backported, such as libguestfs, the SELinux sandbox and the kiosk mode.
Homepage: Red Hat
Although the newest Red Hat Enterprise Linux (RHEL) release is 6.1, Red Hat continues with updates for its previous 5.x release. The latest RHEL 5.7 gets some of the goodies of RHEL 6.x, in particular with respect to KVM: migrating KVM virtual machines is faster, CD drive emulation is enhanced and issues with the boot order of virtual machines have been fixed. But even if you stay with the Xen hypervisor, which is the default one in the 5.x product line, there are several performance improvements for you, including faster booting and xz compression support in PyGrub. And although Xen isn’t supported anymore in RHEL 6, it’s still fully supported in RHEL 5 until at least 2014 (when the distribution’s regular life cycle ends).
Of course RHEL 5.7 also comes with better hardware compatibility: there’s support for newer hardware that has been introduced this year, including Intel, AMD, POWER and IBM System z systems. This not only applies to processors and chipsets, but also to storage, networking and graphics. Security managers will be delighted to see that RHEL 5.7 supports the Security Content Automation Protocol (SCAP), including the OpenSCAP utilities to verify the system’s security configuration and vulnerability status. Also, a wide range of notable enhancements were made to the System Security Services Daemon (SSSD), and support for LDAP has been improved in Autofs to enhance centralized management of user filesystems in an enterprise environment.
In parallel with RHEL 5.7, Red Hat is also introducing a new subscription service, Red Hat Subscription Manager. It offers both GUI and command line tools to manage your system and its allocated subscriptions. While in previous releases your subscriptions were based on access to channels and were assigned to your organisation as a whole, the new subscription process assigns your subscriptions to particular installed products and individual systems.
As a consequence, the Customer Portal now provides both subscription services: a certificate-based Red Hat Network for the new service and Red Hat Network Classic using the traditional channels. Unfortunately, there is no direct supported migration path from your systems using RHN Classic to the new certificate-based RHN. It’s also weird that despite this focus on the new subscription model the setup program still enables “RHN Classic Mode” by default, and there’s no explanation in the installer about the differences.
Red Hat Enterprise Linux has always been strong in the domains of security and virtualization. With RHEL 5.7, you have the choice between Xen and KVM as your hypervisor. Unfortunately, RHEL 5.7 still doesn’t have the very useful libguestfs tools to manipulate disk images of virtual machines, but there are some unsupported and untested binaries available that should work on RHEL 5.6 and higher. This is one important feature that didn’t get backported from RHEL 6. In the domain of security, RHEL 5.7 also didn’t get the SELinux sandbox and the kiosk mode, both useful features that have been introduced in RHEL 6. However, RHEL 5.7 has all the basic features that make Red Hats distribution the number one secure enterprise Linux distribution, such as SELinux and the SELinux troubleshooter.
Despite all the improvements, the kernel and user application programming interfaces (APIs) remain unchanged, ensuring that all your RHEL 5 applications do not need to be rebuilt or re-certified when running on RHEL 5.7. For instance, RHEL 5.7 still comes with the old 2.6.18 Linux kernel. However, the 5.x product line reaches the end of its first phase (Production 1) at the end of this year, and after this Red Hat will not add major new functionality nor major hardware compatibility enhancements, so the time for a migration to RHEL 6 is fast approaching.
If you want to have the latest and greatest in enterprise Linux land, you should be running RHEL 6.1, but if you’re still running the 5.x line on your servers and you can’t upgrade your infrastructure to 6.x for whatever reason, the hardware compatibility and performance enhancements of RHEL 5.7 are really welcome.