Red Hat Enterprise Linux (RHEL) 5 is a fully-supported open-source server operating system that is suitable for a range of hardware and includes the latest Xen virtualisation tools.
Most enterprise customers are likely to buy the RHEL 5 Advanced Platform. This costs €1,500 (£1,000 + 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 two processor sockets and running no more than four VMs could also use the standard RHEL 5 product, which costs €340 (£230 + VAT).
Release 5 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. 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.
IT Week tested RHEL 5 by installing it on a single-processor server fitted with a Pentium 4 chip, two SCSI hard disks and 2GB of RAM. The installation utility asked for a licence number and will not install some closed-source software components without it.
The Xen support is certainly the most notable addition. Firms can now host Windows and a wide range of other operating systems on RHEL servers, so long as they are fitted with processors that can support virtualisation, such as the Intel VT or AMD VT chips.
Even without those processors, Xen’s support for paravirtualised (PV) operating systems means it can host virtual servers running versions of Linux specially prepared for use with Xen. RHEL 5 normally uses this PV-compatible kernel and Red Hat wants software vendors to certify their software using it. The result should be that most people using RHEL 5 will be using the PV kernel, which should be good for firms using Xen.
RHEL 5 includes a number of tools to help server administrators create VMs, move them around and back them up. The industry is still some way from settling on a single set of tools to handle these management 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, a graphical tool that works with Libvirt to provide an easy-to-use console for managing Xen VMs. Another tool, 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 to the operating system include the addition of around 200 new policies for SELinux, which will make it much easier for administrators to use the security subsystem to protect Linux servers from hackers.
Similarly, software developers get SystemTap, a new tool that will help debug applications. SystemTap is an open-source equivalent to Sun’s DTrace and can be used to see how a program interacts with the operating system and the server hardware.
