Introducing Linux into the Enterprise

Those of us who use Linux on a daily
basis greatly appreciate its power and flexibility, not to mention
its resistance to virus threats. Linux's raw performance, stability
and incredible toolset all combine to make it an obvious choice for
mission-critical servers in the enterprise. But in order to
continue gaining acceptance into a primarily Microsoft world, we
must continue to find ways to deploy Linux and exploit its robust
capabilities, while at the same time help IT managers and system
administrators realize its incredible benefits. This article
discusses how our IT group was able to accomplish plugging Linux in
to a once Windows-only environment and save thousands of dollars in
the process. We look at using Linux as a platform for server
consolidation, and if you stick with me, I promise to show you some
cool tricks that will save you hours of work and subsequent
administrative headaches.Introducing Linux to the EnterpriseIf one can find a bright spot in the dot-com meltdown of
2000, it would have to be the renewed interest in emerging and
cost-effective technologies. Server consolidation is one such
technology that needed to be explored as a way to save money and
keep businesses running--enter Linux and a special piece of
software called GSX Server, from VMware Inc. in Palo Alto,
California. VMware is not a newcomer to the Linux community, having
released a workstation product several years ago that allows users
to run multiple unique operating systems on a single computer,
without the need to multiboot--an extremely useful tool for help
desks and developers alike.But VMware's GSX Server is quite a bit different from its
workstation tool. Once installed, GSX runs on top of Linux,
providing an environment that allows you to run multiple virtual
server instances. In our case, we needed additional Windows NT 4.0
and Windows 2000 servers to provide development and test
environments for new projects. Because tighter budgets did not
allow for buying additional hardware, we decided to take a serious
look at VMware's GSX Server. Can this thing work? Can virtual
servers really replace individual chunks of hardware and provide
acceptable performance and stability? Both of these questions could
be answered only through thorough testing of the product.Choosing Hardware for GSXWe began by building GSX test servers with Red Hat 7.0 and
GSX version 1.1 on an NCR S50 (550MHz quad) and a couple of Compaq
DL380 and DL580 servers (733MHz and up, dual and quad processor).
Early testing on some older hardware demonstrated that virtual
server performance was not up to par on hardware with less than
500MHz processors. But with hardware running at 550MHz and above,
the performance of our virtual servers proved to run at near native
speed. Something to keep in mind when measuring performance is that
virtual servers are accessible only to end users via remote access
technology, such as VMware's included remote console, Microsoft
Terminal Services or a product like pcAnywhere (my personal
preference). As such, network latency needs to be taken into
consideration when measuring virtual server performance. As for
stability, there is a noticeable improvement as seen in fewer
server crashes and blue screens while running Windows NT and 2000
servers in the GSX virtual environment. The real acid test, of
course, is the end users. When they can't tell the difference and
don't complain, life is good.Needless to say, we were quite impressed with this technology
and the performance of our virtual servers. We saved thousands of
dollars on hardware by hosting six virtual servers on a single box,
have less physical servers to administer and back up, and
surprise--the virtual Windows instances are more stable than when
installed directly on top of the physical hardware (fewer BSOD
events; go figure).Not long after we had begun testing the GSX 1.1 product,
VMware offered to let us begin working with the newer 1.02 version
of GSX Server. This allowed for testing of the new 2.4.x kernel in
Red Hat 7.1 and provided for increased server memory from (2GB to
4GB) under the new GSX. Performance of the virtual servers and
stability of the VMware remote console was much improved with the
new version of GSX. In addition to the aforementioned improvements,
we were also able to run additional virtual servers (now up to
eight or more) due to the increase in maximum server memory.Installation and Configuration of GSX
ServerBuilding a VMware GSX Server on top of Linux is easy. VMware
offers a 30-day evaluation version that you can download from their
web site and install. After completing a quick registration form
where you provide your e-mail address and name, select the version
appropriate to your distribution and download. For this article we
will be using the RPM versions of GSX, but other packages are
available for various distributions. Typically within minutes of
registering with VMware, you will receive an e-mail with the 30-day
license key attached.As for your host server, you have a choice of Linux
distributions, such as Red Hat, Caldera, Turbolinux and SuSE.
During the installation of your particular distribution, you will
want to consider a partitioning scheme similar to what is shown in
Listing 1. The /var, /temp and /home partitions require additional
space for log and temp files and, of course, the virtual instances
themselves.Listing 1. Partitioning
SchemeBecause our servers came configured with 80GB of disk space
that we set up in a RAID-5 array, we had a fair amount of disk
space to work with. But in order to save additional disk space for
the virtual servers, you may want to choose the custom build
install option (Red Hat being the example here) and exclude
unnecessary packages, such as games, multimedia, printing, DNS,
laptop and so on. Be sure, however, to the include Apache, Samba,
networking utilities, the X Window System, compilers and kernel
source packages. Once the build is completed, copy the downloaded
VMware files to the host server. You also should download the
install and configuration documents from VMware's web site to refer
to as we begin the GSX installation.Working as the root user, first install the GSX engine as
follows:rpm -ihv
vmware-gsx-1.0.3-1527.i386.rpmThe RPM packages will notify you of any missing dependencies
you may need to resolve (a rare occurrence). Once the RPM
installation is completed, change directories to the /usr/bin
directory and run the GSX installer script:./vmware-config.plThis is a Perl script that will walk you through the
installation of the GSX engine. You will be prompted to answer
several questions regarding network configuration and file
location. When prompted, answer Yes to Bridged networking and No to
Host Only. Accepting the defaults for file locations is fine. When
you are prompted to enter a serial number to register the product,
refer to the license information sent to you by e-mail. Next, GSX
will determine if it has precompiled kernel modules appropriate for
your particular distribution. If it does not find compatible
modules, GSX will attempt to compile them for you, prompting you
for the location of the kernel source files (now aren't you glad
you installed them?). After the script has completed this portion
of the installation, change back to the directory that you copied
the GSX files to (I use the /root directory) and type:tar -xzvf
vmware-mui-1.0.3-1527.tar.gzAfter the tar extraction completes, you will have a new
directory with the name vmware-mui. Change to the /vmware-mui
directory and type:./vmware-install.plYet another Perl script will begin installing the rest of the
GSX package, including necessary Perl modules and additions to the
Apache configuration for the web-based administration interface to
GSX. Once the Perl script has completed, you will have a working
version of the GSX Server running on top of Linux.One additional package you may want to install is the
vmware-console-1.0.3-1527.i386.rpm. This package allows you to use
the graphical interface to build virtual instances locally on the
Linux server rather than only from a remote console.Now that we have all the VMware GSX goodies installed, we
need to verify that GSX is running. From the command line,
cd to the /etc directory and type
rc.d/init.d/vmware status or service
vmware status. You should receive verification that the
vmware dæmon is running and that a single instance of vmnet
is also running (vmnet is the virtual network bridge that allows
our Windows instances to talk through the Linux hosts' hardware,
eth0, etc.).Finally, bring up a web browser and point it to the host
server's name or IP address followed by port 8222 (see Figure
1).
Figure 1. VMware Remote Console
You will be prompted to log in (as root) to the console where
you will be greeted by a web interface. The GSX host console allows
you to create new virtual servers and monitor existing ones as they
run. You can also launch the remote consoles from within the web
admin tool and log in to your virtual server instances once they
are built. God love those geniuses at VMware.All that is left to do is create servers in the new web
console, then boot the virtual server to your install media. In the
web console, click the New VM button to begin creating your virtual
servers. You will need to provide a name for the instance, its
location on the server (i.e., /home/vmware/win2k) and the amount of
memory and disk space allocated to it. Be sure to enable networking
and set video resolution to 8 bit (for better performance). Once
the virtual instances have been created, place your bootable media
in the appropriate drive on the host server and launch the GSX
remote console. Just click the Power On button and watch the magic
as a virtual computer comes to life, complete with Phoenix BIOS. If
you are booting from CD, the next thing you will see is the
installer program of the OS you have chosen. From this point on,
it's business as usual.What to Do with All the Extra Time?So now it's time for some of those cool tricks I promised.
Would you believe me if I said that you can build a complete
Windows 2000 or NT 4.0 server in just a few minutes under GSX? Or,
how about multiple servers at the same time in under an hour?
Here's how it works. The first build of an operating systems in GSX
takes the usual amount of time to complete and configure, but if
you need multiple servers with the same base build or similar
configuration, you can copy the files created after the initial
build to subsequent virtual server directories. Simply create the
new servers in the web admin console as before, copy the server
files, then change a few lines of information (such as server name
and the pointers to the new server's disk files, *.dsk) in a config
file (i.e., win2000.cfg). After that, power on the new servers and
change their IP address, machine name, etc. It's a good idea to
tarball the files, name them appropriately and copy them off to a
DLT, CD burner, etc. Now pat yourself on the back because you built
multiple identical servers in minutes. At this point you can
customize your servers to be SQL, web, e-mail, etc.In addition, GSX gives you a fast way to build multiple
servers and a much quicker way to recover from a serious crash. In
the event of an unrecoverable OS failure (you were backing up,
weren't you?), rather than having to rebuild the OS and then
restore your data, copy the server files from the tarballs that you
created. Now restore your data and calmly say to yourself, "life is
really, really good".So there you have it--a high-powered Linux server that can
host as many virtual servers as you have the memory and the
horsepower for. I encourage you to visit the VMware site and check
out the GSX Server product (there is also an ESX Server product
that runs directly on top of the hardware--no OS), and give the
30-day demo a spin. For our purposes, Linux combined with VMware's
GSX Server have been a real blessing.Jeffrey McDonald works as a
systems engineer for a California-based Fortune 500 company. He has
been working with Linux for the past five years and enjoys
promoting Linux.

email: jsmcdon1@yahoo.com