Highlights of a Blockbuster—Novell Open Enterprise Server 2
Over the past year or so you’ve no doubt heard many of the benefits of Xen virtualization provided in SUSE Linux Enterprise Server 10, such as server consolidation, workload isolation and even disaster recovery through dynamic server migration. These benefits are of great interest to Novell customers—and reason for many of them to make the move to Linux. But there is one virtualization benefit that has received only nominal attention: the ability to run NetWare® in a virtualized environment and thus preserve NetWare-specific applications or skill sets on which your business can depend. You may want to leverage your NetWare-dependent applications while you gradually migrate to Linux. Or maybe you want to continue running NetWare while taking advantage of the latest and greatest hardware. Either way, you can use the virtualization capabilities inherent in the SUSE Linux Enterprise Server 10 kernel of Novell Open Enterprise Server 2 to achieve your objectives.
Even though NetWare has been enhanced to recognize that it’s running as a virtual server, it is still basically the same reliable NetWare you’re used to.
> Enhanced for Virtualization
In Novell Open Enterprise Server 2, you have the choice to deploy NetWare 6.5 SP7 on either a physical machine or in a virtual machine using Xen virtualization. The NetWare 6.5 operating system has been enhanced to recognize when it is running in a virtualized environment. This is known as paravirtualization.
With paravirtualization, the NetWare operating system runs inside a virtual machine as a virtualized guest operating system on top of the virtual machine monitor, also known as the Xen hypervisor. The virtual machine monitor is a software layer developed and maintained by the Xen open source community. The virtual machine monitor runs between the server hardware and the SUSE Linux operating system kernel and has the responsibility to allocate resources to the virtualized guest operating systems. It presents them with virtual machines that act like the guest servers’ native architectures.
While a fully virtualized operating system has to “trap” information from the executing instruction stream, a paravirtualized operating system doesn’t require this and provides performance gains as a result. In addition, with paravirtualization, the virtualized platform doesn’t have to emulate the actual hardware platform. This leads to additional efficiencies in circumstances such as accessing page tables that control memory.
Finally, a paravirtualized operating system communicates using a set of virtualized, rather than physical, drivers. Since the host OS takes care of the physical driver requirements, it presents a significant benefit to NetWare customers who want to take advantage of the latest advances in hardware technologies, but haven’t found the necessary driver support. Because NetWare can run as a paravirtualized guest OS that loads virtual drivers, it no longer needs to worry about physical drivers. Given that the host OS is Linux, which has vast and ever-growing driver support, paravirtualized NetWare automatically inherits that entire driver base.
From a management standpoint, NetWare administrators manage NetWare in a virtual machine much the same way they manage NetWare on a physical machine.
However, even though your NetWare virtual machines automatically load virtual drivers, you still have the option to load physical drivers. (see Figure 1.) Utilizing physical drivers lets your virtual machine interact directly with the physical hardware. One reason for doing this might be to gain a little extra performance from your network card; however, a more likely reason is to allow direct interaction with a tape backup device to reduce I/O overhead. But be aware that using physical drivers could impact some virtualization operations such as migrating a virtual machine from one physical server to another.
> NetWare as You Know and Love It
Even though NetWare has been enhanced to recognize that it’s running as a virtual server, it is still basically the same reliable NetWare you’re used to. It’s simply operating in a new environment that presents opportunities and capabilities you didn’t have before.
In fact, paravirtualized NetWare utilizes the exact same binary code that runs on bare metal machines with just a few exceptions. The first exception is the loader file. Physical NetWare utilizes NWLOADER.SYS while virtual NetWare uses XNLOADER.SYS, which basically just tells the server that it’s running in a virtual environment. The only other binary difference is in the drivers that are loaded. In a virtual NetWare environment you’ll typically load virtual drivers that interact with Xen rather than discrete drivers that interact with actual physical components. These virtual drivers are primarily comprised in the files XENBLK.HAM, XENNET.CAD and XENMP.PSM.
Also, according to Novell engineering, more than 95 percent of the NLMs in NetWare required no changes to run on a NetWare virtual machine. When changes were needed, it was typically because the NLMs contained privileged or sensitive CPU instructions, accessed hardware directly or expected to run at ring zero.
Such was the case with the SERVER.EXE file, which required the most changes. But this also means you shouldn’t have problems running your third-party NLMs, unless they fall into one of the above categories. With regard to backup and antivirus NLMs, Novell is working closely with those vendors to ensure that their solutions will run without problems in a virtual environment.
From a management standpoint, NetWare administrators manage NetWare in a virtual machine much the same way they manage NetWare on a physical machine. Management tools such as ConsoleOne, iManager and Novell Remote Manager all work the same. But now you have even more ways to manage your NetWare server. In addition to traditional NetWare management tools, you inherit the ability to take advantage of Linux management utilities and console commands, because the virtual machine is running in a Linux environment. (See NetWare Commands & Linux Counterparts.)
> Getting the Most Out of Your Hardware
One of the major benefits of running NetWare as a virtual machine in Novell Open Enterprise Server 2 is that it allows you to fully utilize your existing hardware investments. Unlike some virtualization solutions, it doesn’t require you to deploy it on servers with chipsets specifically enabled for virtualization. In fact, if your current NetWare servers have fairly low CPU utilization, you might even be able to host multiple NetWare virtual machines on one of your existing servers. Thus enabling you to take advantage of the benefits of server consolidation.
But running NetWare as a virtual machine does provide you the added option of moving up to even higher performing hardware if desired. This enhances your ability to do server consolidation, and take better advantage of 64-bit processors. By running NetWare as a virtual machine in Novell Open Enterprise Server 2, you are no longer 32-bit bound. You can take full advantage of the extra processing power, added memory capabilities, and improved heat and energy savings offered by 64-bit dual-core and multi-core processors.
NetWare Commands & Linux Counterparts
Since virtualized NetWare runs hosted in a Linux environment, it’s helpful to be familiar with some of the standard Linux commands. Novell partner BrainStorm, Inc. provides an Administrator’s Command Reference for Novell Open Enterprise Server that shows common NetWare commands and their Linux counterparts. The following are a few examples of these command mappings:
- CLS for NetWare and clear for Linux: clear the console screen and move the console prompt to the top of the screen.
- DSRepair for NetWare and ndsrepair for Linux: maintain and repair the database of an eDirectory tree.
- VIEW for NetWare and cat for Linux: view a file from the NetWare server console.
The complete command reference can be found at BrainStorminc.com/oes.
In addition to preserving all of your trusted NetWare services on today’s high-end hardware platforms, server consolidation is one of the main reasons for employing virtualized NetWare. With NetWare virtual machines in a Novell Open Enterprise Server environment, you could consolidate three or more physical NetWare servers into guest virtual machines that run on a single physical box. (see Figure 2.) You can also host Linux virtual machines on that same hardware. This ability to host both Linux and NetWare as virtual machines on a single box can also facilitate migration efforts from NetWare to Linux by allowing you to preserve access to any NetWare-dependent applications and services while you transition your IT environment and skill sets to Linux. To help you with your consolidation efforts, you can also leverage the Open Enterprise Server Migration Figure 4 Using a response file during the installation of a NetWare virtual machine can be useful when you need to create multiple NetWare virtual machines. Figure 3 Create Virtual Machines is one of three installation methods in YaST for creating a NetWare virtual machine. Tools that ship with the product and the Novell Open Enterprise Server Migration Web site at novell.com/oesmigrate.
In addition to preserving all of your trusted NetWare services on today’s high-end hardware platforms, server consolidation is one of the main reasons for employing virtualized NetWare.
> Deployment Considerations
Before you deploy NetWare as a virtual machine, consider your storage options. Will you use a SAN or NAS, or will you use storage local to the physical server hardware? Be aware that if you use local storage, it will prevent you from doing an on-the-fly migration of a virtual machine from one physical server to another.
Also, if you’re hosting multiple virtual machines on the same physical server, pay attention to their various workload types. If you overload your physical server with multiple virtual machines with the same type of workload, you could run out of CPU, memory or I/O bandwidth. For example, if all of your virtual machines perform disk-intensive operations, they could use up the entire bandwidth of your disk array.
> Installing Virtualized NetWare
NetWare 6.5 SP7 will run as a guest operating system on top of a SUSE Linux Enterprise Server 10 SP1 host server. The physical server will need to have at least 512 MB of RAM for the VM host server and 512 MB of RAM for the NetWare virtual machine. However, for better performance, using a server with 2 GB of RAM or more is recommended.
SUSE Linux Enterprise Server 10 SP1 will need to be installed and configured as the virtual machine host server, selecting Xen Virtual Machine Host Server from the Primary Functions software selection category. To optimize the host server to manage the virtual machines, it should be configured without any Open Enterprise Server services. These should be installed on an Open Enterprise Server virtual guest OS or a physical NetWare installation.
In keeping with the desire not to run additional services on a host server, the Print Server from the Primary Functions category should be deselected. Furthermore, Novell eDirectory should not be running on the host server.
After the host server installation and configuration finishes, and the system reboots, the following steps should be performed to finalize the host server configuration:
- Log in as root and change the default boot loader to the Xen kernel.
- Reboot the system.
- Configure NTP on the host server.
- Disable the Alt-Escape desktop shortcut, if using GNOME.
After the host server is up and running, a virtual machine for NetWare can be created using one of three installation methods—each with an icon in YaST.
> Virtual Machine Manager
The “Virtual Machine Manager” option launches a program called virt-manager. To create a NetWare virtual machine using virt-manager, click Virtual Machine Manager in YaST and select New. This will launch a program called vm-install that will guide administrators through the creation of a NetWare virtual machine. Using virt-manager is advantageous because it provides a console that is VM-specific and doesn't allow most keyboard commands to be intercepted by the Linux desktop. In other words, most of the keyboard commands familiar to NetWare administrators will work as they always have.
> Create Virtual Machines
The second option in YaST is “Create Virtual Machines,” which launches the vm-install program directly. (see Figure 3.) One advantage of using the Create Virtual Machines option directly is that it allows administrators to run vm-install in pure text or graphical user interface (GUI) mode, while virt-manager requires a GUI. However, launching vm-install with this icon bypasses virt-manager and will not result in NetWare keyboard control. This is the reason for the instruction to disable certain shortcuts in the Gnome desktop.
> Response File Utility
The last installation option, which is particularly useful if multiple NetWare virtual machines will be created, is to use the Response File Utility to enable unattended installations. A response file is created in YaST by:
- Selecting Open Enterprise Server from the menu and then selecting the NetWare Response File Utility. (This utility is installed automatically on every Open Enterprise Server 2 Linux server.)
- On the Select Install Type page, the hardware type should be set to Virtual.
- Select the type of server installation you are creating the response file for: new server install, server upgrade, or two-part factory installation
- The Response File Generator will ask for information about the NetWare server that will be created as a virtual machine. The questions should be answered the same way they would be if a physical NetWare installation were being performed. If a response file for NetWare 6.5 is already available, this can also be used to generate a virtual NetWare server.
If a response file is used, the install can be initiated by:
- Clicking Virtual Machine Manager in YaST.
- Selecting Find from the Operating System Installation menu option.
- Browsing to the location of the response file. (see Figure 4.)
After it is opened and applied, YaST will proceed with the creation of the virtual machine and the installation of the virtual NetWare server. If a required parameter is missing in the response file, the administrator will be prompted to enter the desired values during the installation. If a response file is not specified, all of the installation information will need to be entered just as if a physical NetWare installation were being performed. For complete details on installing NetWare virtual machines, refer to the online documentation for Novell Open Enterprise Serve 2 at www.novell.com/documentation/oes2/.
Once your virtual machines are created, you can manage them using the Virtual Machine Manager utility, which allows you to do things such as add, view, start, shut down and terminate virtual machines. You can also manage your virtual machines from a terminal using xm commands. (See Virtual Machine Commands.)
> More to Come
The ability to preserve your NetWare services in a paravirtualized NetWare virtual machine is only one of the many benefits provided by Novell Open Enterprise Server 2. In addition to virtualization, you’ve already read about Domain Services for Windows and Dynamic Storage Technology in earlier segments of this Novell Connection magazine series on the top features of Novell Open Enterprise Server 2. Watch for the final segment in next month’s online version when we cover how Novell Open Enterprise Server helps you finalize your transition to Linux.
Virtual Machine Commands
The following are virtual management commands that can be executed from a terminal when logged in as root.
- xm help: view a list of subcommands available for the xm command.
- xm list: view a list of all running virtual machines.
- xm create /etc/xen/vm/vm_name: start and view a virtual machine. A paravirtualized virtual machine starts but does not display. A fully virtualized virtual machine starts and displays according to the settings in the virtual machine configuration file.
- xm create /etc/xen/vm/vm_name -c: start and view a paravirtualized virtual machine.
- xm console vm_name: view the console of an already-running paravirtualized virtual machine.
- xm mem-set vm_name MB_Memory: change the memory available to a paravirtualized virtual machine.
- xm shutdown vm_name: perform a normal shutdown of a paravirtualized virtual machine’s operating system.
- xm destroy vm_name: terminate a virtual machine immediately. This basically emulates turning off the power to a physical machine and is (just like the power button) a last resort and could cause other problems. Be aware that this command might cause file system corruption.