Novell SLES 10.2 Xen offers great promise

Novell's SLES 10.2 with Xen 3.2 is part of its Linux product line and typically is managed by the company's ZenWorks products and services.

Novell's SLES 10.2 including Xen 3.2 is part of its Linux product line and typically is managed by the company's ZenWorks products and services. However, Novell refused to supply its Orchestrator management platform with a ZenWorks virtualization management module for this review, stating that Orchestrator is customized for each data center deployment via Novell Consulting Services and, therefore is not an appropriate product to be included in lab-based reviews. Therefore, our assessment of Novell's offering rides solely on the SLES 10.2 Xen implementation and the tools bundled with it..

In terms of compatibility, Novell's Xen supports everything that the x64 version of SLES 10.2 does. This list of supported server hardware foundations is the best of the three Xen competitors. The list of the guest operating systems it supports, however, is narrower than both Virtual Iron's and Citrix XenServer's. The Novell list includes paravirtualized SLES 10, NetWare 6.5, Microsoft Windows Server 2008, fully virtualized Windows 2000, 2003, XP, fully virtualized SLES 9, and RHEL versions 4 and 5. Missing from this list are Windows Vista and CentOS versions.

The initial installation of Novell’s SLES Xen is exactly the same as the installation of SLES 10.210 (see test), with the sole variation being the installation of precompiled Xen kernel. We implemented the 64-bit Xen kernel but there also is a 32-bit kernel available from Novell.

Two GUI applications are available with Novell's Xen bundle, which we used to facilitate installation. The vm-install tool provides a templated VM creation method that's somewhat similar to Citrix's XenServer templates. We used setup utilities familiar to us from our long history with SLES versions for networking and shared storage. VMs we created could be paravirtualized (usually Linux guests only) or fully virtualized Windows guests.

Novell's SLES Xen package includes a rudimentary virtualization application called Virt-Manager (short for Virtual Machine Manager, not to be confused with Microsoft tool with the same name!) — a common, lightweight GUI application included in Xen-based virtualization products.Virt-manager has an option called Create Virtual Machines, which we invoked before installing Windows and SLES as guest machines. Then we set up each VM's allocation of RAM, CPUs, hard disk and networking, and selected whether we wanted the guest to be paravirtualized or fully virtualized. If a VM will be connected to shared storage, that storage needs to be set up as a directory beforehand. This includes iSCSI or Network File System (NFS) shares used for VM storage managed from the SLES installation; they’re more difficult to allocate post-installation.

We performed simple day-to-day management tasks primarily via a single command-line-interface (CLI) command called "xm" and a series of shells built around it that let us complete ongoing VM management. Xm lets you destroy, pause, reboot, shut down and save a VM’s guest state.

Novell supplies a script called "xmclone.sh" that creates a copy of a VM. We found it straightforward and simple to use. The only problem with this process is that it can copy instances only to the same server — not to another virtual host. To move the image to another machine, we had to move the VM snapshots we took to shared storage manually.

Xm also does basic monitoring, and shows uptime, real-time state, configuration and CPU information. Through xm, you can change memory-use boundaries and the number of vCPUs available within domains.

From the xm command line, you can read logs and do troubleshooting. For example, we could view the message buffer logs using the xm-dmesg command to peek at the logs during various phases of testing.

Reconfiguring network connections for VMs with Novell's tools was tedious. Because it uses a virtual network adapter, making changes to network settings required that we boot a non-Xen kernel, then reboot back into Xen.

Novell SLES Xen had no alarms, events or Xen-specific reports — just those that can be found in SLES 10.2, which aren't useful for VM monitoring or alarm management.

SLES 10.2 Xen had one unique management feature among competitors in that it let us change the number of CPUs allocated to a VM while the VM is running (if it is paravirtualized). We found this ability to reallocate CPU muscle to an application to be useful.

Novell's SLES 10.2 Xen uses native security and password-access policies, which are chosen as the default security for the overall operating system. Directory-access user security is enforced via SUSE's native supported APIs (LDAP, Kerberos). SUSE Xen supports access via Secure Shell or a certificate. As with Virtual Iron, there are no restrictions placed on users in SLES 10.2 Xen to let them start or stop VMs.

Consolidation and migration

Novell's SLES Xen does not have a P2V tool in its bundle. PlateSpin is a Novell company, however, so that's a P2V option at a price, and Novell did not include it in the tested bundle. Virtual Iron OEMs the technology, however, and we tested it as part of that package.

The general SLES 10.2 Xen migration processes worked in our testing only for active paravirtualized guests. It doesn't work if the VM is fully virtualized or turned off, capabilities that competing Xen implementations can carry out. Another snag in Novell's migration pattern is that a VM migration via iSCSI was only temporary; it did not stick to the new machine if we rebooted or shut it down.

Snapshots (called checkpoints here) are also available with the Novell implementation via a command-line string: - xm save -c <domain> <checkpoint file>. If we used the -c option, the server continued running (temporarily pausing, however). If we performed a save, the VM was halted. We could then resume from the previously set checkpoint using the xm restore <checkpointfile> command.

Novell's SLES 10.2 Xen would seem to have great promise for a number of applications that require virtualization, and its value as a member of the normal SLES 10.2 'box' gives it high value, absent Novell's Orchestrator. Linux-savvy administrators can certainly make Novell's Xen work for them.

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