Launched on 14 March at the CeBIT exhibition in Europe and at a press conference in San Francisco, Red Hat Enterprise Linux (RHEL) 5 packs the last 2 years of improvements in open-source into a commercially supported server operating system suitable for a very wide range of hardware.
In a nutshell, the biggest changes have been to improve its support for virtualisation.
While some server virtualisation tools have been available in Red Hat’s unsupported Fedora Core project since version 3, until now these had not been available in RHEL. However, the open source Xen project for developing server virtualisation tools has made substantial progress over the last two years and these updates have now been incorporated into RHEL 5.
Prices and packaging have also been updated and the RHEL suite is now offered in two versions. Most enterprise customers will buy RHEL 5 Advanced Platform, which costs £1,451 + VAT and is licensed to run on any number of CPUs and with any number of virtual machines (VMs). Low-end servers fitted with no more than 2 processor sockets and running no more than 4 VMs could also use the standard RHEL 5 product, which costs £337 + VAT.
This release also sees the addition of several storage virtualisation tools into the base operating system. In particular, RHEL 5 Advanced Platform includes Red Hat Global File System and Red Hat Cluster Suite, which were previously sold separately for about £2,200. These storage virtualisation tools enable IT managers to connect several servers to the same disk storage systems, making it much easier to build fault tolerant applications.
We tested RHEL 5 by installing it onto a single processor server fitted with a Pentium 4 processor, 2 SCSI hard disks and 2 GB. The installation utility asked for a license number and will not install some items without it.
In The Hypervisor labs tests, we found the new Xen support to be the most interesting addition in RHEL 5. Firms can now run Windows and a wide range of other operating systems on Red Hat Enterprise Linux servers fitted with processors that include hardware support for virtualisation, called Intel VT and AMD V respectively. Even without those processors, Xen’s support for para virtualised (PV) operating systems means it can host virtual servers running versions of Linux specially prepared for use with Xen. In fact, RHEL 5 normally uses this PV compatible kernel and Red Hat wants independent software vendors to certify their software using this kernel. The result should be that most people using RHEL 5 will be using the PV kernel, which should be good for firms using Xen.
But although the Xen support is interesting, it would be just about useless without some tools to help server administrators manage VMs, such as by helping them to create VMs, move them around and back them up. Unfortunately it seems the industry is still some way from settling on a single set of tools to handle these tasks. For its part, Red Hat is putting its weight behind an open source project called libvirt, which is a library of functions that other software developers can use to interact with Xen and its VMs. RHEL 5 also includes virtManager, which is a graphical tool that works with libvirt to provide an easy to use console for managing Xen VMs. In addition, virsh provides a Linux shell environment that interacts with libvirt, enabling server administrators to interact with Xen using scripts to automate repetitive tasks.
Other improvements include the addition of around 200 new policies for SELinux, which will make it much easier for administrators to use the SELinux subsystem to protect servers from hackers. Similarly, software developers get systemtap , a new tool that will help debug applications. Systemtap, or system tracing and profiling, is an open source implementation of Sun’s dtrace, and can be used by developers to see how a program interacts with the operating system and the sever hardware.
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