1. Introducing iSCSI
One of the most popular methods
for storing both data and virtual operating systems is iSCSI. A relative
new kid on the block, Internet Small Computer Systems Interface (iSCSI)
is very popular for virtualization solutions because iSCSI devices can
be installed via TCP/IP protocols and receive standard SCSI commands.
In the enterprise,
most iSCSI configurations are stored in arrays of disks that are
managed through external software in proprietary enclosures, such as
those made by EMC2 and other
companies that produce disk arrays. Using iSCSI, administrators can
easily create RAIDs of various disks and then assign further details to
these RAIDs using logical unit numbers (LUNs).
1.1. Logical Unit Numbers
To understand logical unit
numbers, it's best to first understand SCSI. In case you're not too much
of a hardware guru, SCSI is a type of I/O method that takes advantage
of a dedicated card that interconnects directly with the PCI bus.
In the old days, or at least
the "older" days, of computing, SCSI was used because it could interface
with higher-frequency buses and transfer more information faster than
the standard PCI bus using IDE technology. SCSI supported a maximum of
16 devices per bus, each of which had its own individual and unique
identifier, or number. You could, for example, have four hard drives
that exist on logical numbers 0, 1, 2, and 3. You could then specify
which drive you wanted to communicate with via some relatively simple
I/O operations.
LUNs come into play when
you have a large device that's attached to one particular SCSI port.
Say, for instance, you have a four-drive disk array that takes only one
SCSI port. If you wanted to break that array into, say, four individual
volumes, you'd have to use both the SCSI port and a logical number for
each drive—the logical unit number.
Using LUNs, the drives
can be identified as individual volumes and be accessed individually.
This is particularly important if you want to use these drives for
virtualization, because for each virtual operating system you have, you
have to have one dedicated volume. With an iSCSI system, you can take a
single array, break this array down into multiple volumes, and assign
them each logical unit numbers. Then, you can take each volume and
assign it individually to a virtualized system.
2. Windows Vista x64 Hyper-V Management
Because of the inherent
flexibility of both the Vista operating system and Server 2008's robust
architecture, Microsoft has made the process of administering Hyper-V
relatively easy. Using Windows Vista 64-bit edition with Service Pack 1,
administrators can log on to a client host operating system and use the
Remote Server Administration Toolkit in conjunction with the Hyper-V
Manager to administer a Hyper-V server from a remote location.
This is useful for a variety of
reasons, but primarily it is useful because it means an administrator
doesn't have to go through the bother of using Remote Desktop to access a
machine or manually logging in. Instead, the administrator can just sit
at their remote location and gain easy access to the Hyper-V server.
NOTE
You have to enable WMI for this installation.
3. Server Core and Virtualization
Just to prove to you exactly
how powerful Windows Server 2008 Server Core really is, Server Core does
indeed support Hyper-V! In this book, I won't go into the procedures
for this, because it isn't practical for our use. However, in your own
environment, it may be a good idea to implement Hyper-V on Server Core.
According to both Microsoft and common sense, a Server Core installation
of Hyper-V reduces your attack surface by using fewer bells and
whistles.
In addition to reducing
your attack surface, you free up valuable memory, which is a rare
commodity with any type of server. Additionally, SUSE Linux and other
installations of Linux-based platforms in the future are often installed
in command-line-only forms. Thus, it doesn't make a lot of sense to
have a full GUI-enabled machine if a command-line-based server will do.
The main difference
between Server Core and full installation Hyper-V setups, beyond the
lack of graphics, is that Windows Server 2008 Server Core has to have
its Hyper-V installation managed remotely via Windows Vista Service Pack
1 or another installation of Windows Server 2008. But, although it's a
downside, it isn't the end of the world. Furthermore, if you have time
on your hands, you can even set up an unattended installation of Server
Core that prevents you from having to set up Server Core again after
you've done it once.
4. Using System Center Virtual Machine Manager 2007
Just like the old saying
goes, "There's the individual way to do it, and then there's the
enterprise way to do it." Well, maybe that's not really an old saying,
or even a saying at all, but it certainly applies here. System Center
Virtual Machine Manager 2007 (SCVMM 2007) is an application available
from Microsoft that deals directly with the process of managing multiple
virtual machines in an enterprise or data-center environment. With
consolidation, it can be pretty easy to get carried away. First you
start with one machine, and before you know it, your entire enterprise
starts to take advantage of the available features of a completely
consolidated environment.
With SCVMM
2007, an individual administrator or team of administrators can support
up to 8,000 virtual machines. That's a heck of a lot of operating
systems in one environment. But there are a couple of gotchas. First,
"only" 400 Hyper-V installations are supported. I put only in quotation marks, because that is a tremendous number of 64-bit platforms running Windows Server 2008.
Among other features, SCVMM 2007 allows you to do the following:
Using SCVMM 2007, the
sometimes painstakingly long process of creating virtual machines can be
dramatically abbreviated. In a clustered array, you can use SCVMM 2007
to simply move one virtual machine's data files from one location to
another. Furthermore, you can delegate certain permissions with little
administrative overhead, as opposed to the long process of manually
moving files from one place to another. The SCVMM 2007 architecture has
two main components: the SCVMM server and the SCVMM agent. I will also
discuss two other components—the database and the library server.
4.1. SCVMM Server
The SCVMM server is the
component that serves the centralized process of the entire virtual
machine environment. Usually, there is only one SCVMM server, and the
rest of the machines communicate with it through the use of SCVMM hosts,
discussed in the next section.
Here are a couple of tidbits you should remember for the Enterprise Administrator exam:
4.2. SCVMM Agent
This component of the
SCVMM 2007 is automatically installed with Hyper-V. The SCVMM agent is a
process that is designed to communicate with the SCVMM server and allow
certain tasks to be completed automatically. Note that SCVMM agents
need to be in the same forest in order to properly communicate with the
SCVMM server.
4.3. SCVMM Database
The SCVMM database is the
location of the SQL server used to support the SCVMM server. Best
practices recommend that this server be running at least SQL Server
2005, but with the release of SQL Server 2008, this will soon become the
recommended best practice.
4.4. SCVMM Library Server
All virtual servers require a
certain amount of data in order to be created. This includes stuff like
the image files required to install the operating systems, as well as a
couple scripts and profiles. The SCVMM library server serves as central
depository for these components by allowing SCVMM access to these files
in one location. This way, you can create or alter images from a
central location and not have to worry about changing CDs or swapping
files. It's quite convenient.
5. Using Virtual Server 2005 R2
Although quickly
becoming replaced by Windows Server Hyper-V, Microsoft Virtual Server
2005 R2 is still a completely viable solution for virtual machine
implementations. In some ways, it is more robust in Hyper-V, because it
does not have the extreme hardware requirements of Microsoft Hyper-V. It
is also available free of charge from Microsoft. Additionally,
Microsoft has issued a management pack that allows Virtual Server 2005
to be managed from a remote distance and administer it, as well as its
virtual machines.
