Section 8.2. ISO Images and WinISO

8.2. ISO Images and WinISO

You'll use ISO images a lot in your virtual infrastructure. Ultimately, you'll have a small or large library of them most likely. WinISO is one of many products that allows you to create ISO images from CDs and DVDs as well as from any single file or collection of files. We chose WinISO solely because we use it and feel it's one of the better products out there for this particular task if Windows is your desktop OS. Just about any similar functioning tool will work. This type of tool is essential for working within a virtual infrastructure since you'll find the use of ISO images within an ESX environment to be critical.

What is an ISO image? (For a definition pulled from Wikipedia, see the Configuring & Implementing sidebar titled "ISO 9660 Defined.") In the context of using ISO images within a virtual infrastructure, an ISO image is a file that's basically a complete copy of the original media from which the ISO image is taken. For example, let's say you want to build a new Windows 2003 Server, Enterprise Edition virtual machine. You can go into your data center, insert your CD-ROM, go back to your desk and then begin the build process. Or, using a tool like WinISO, you can create a bootable ISO image from your Windows 2003 media at your desktop, place the ISO image on your ESX Server with tools like WinSCP (which we'll discuss later in this chapter), and then access the ISO image by simply changing your virtual machine's CD-ROM configuration. This way you never physically have to touch your ESX Server, wherever it may be, and yet you still have access to CD-ROM images from your virtual machines.

Configuring & Implementing…
ISO 9660 Defined

The following is the definition of ISO 9660 pulled from Wikipedia at http://www.wikisearch.net/en/wikipedia/i/is/iso_9660.html:

ISO 9660, a standard published by the International Organization for Standardization, defines a file system for CD-ROM media. It aims at supporting different computer operating systems, such as Microsoft Windows, Mac OS, and systems that follow the UNIX specification, so that data may be exchanged.

DVDs may also use the ISO 9660 file system (although the UDF file system is far more commonly used).

Levels and Restrictions

There are different levels to this standard:

• Level 1 File names are restricted to eight characters with a three-character extension, uppercase letters, numbers, and underscores; the maximum depth of the directories is eight.

• Level 2 File names may be up to 31 characters.

• Level 3 Files can be fragmented (used on CD-Rs written by the software "Direct CD" for Windows, for example).

All levels restrict names to uppercase letters, digits, and underscores (_). Some CD-mastering applications allow the user to use almost any ASCII character. While this does not strictly conform to the ISO 9660 standard, most operating systems that can read ISO 9660 file systems support the use of most ASCII characters as an extension.

The restrictions on filename length and directory depth have been seen by many as a more serious limitation of the file system. While in many cases, it's possible to rename files or truncate the filenames in question, and many CD burning applications do this automatically, in certain special cases, this isn't feasible. For example, class files in Java are required to follow strict naming rules, which, especially in the case of nested classes, may require filenames longer than 31 characters.

Disk Images

Disk images of ISO 9660 file systems (ISO images) are a common way to electronically transfer the contents of CD-ROMs. They often have the filename extension .iso (though not necessarily), and are thus commonly referred to as "ISOs."

Extensions

Common extensions to ISO 9660 exist to deal with the limitations. Rock Ridge supports the preservation of Unix permissions and longer ASCII-coded names; Joliet supports names stored in Unicode, thus allowing almost any character to be used, even from non-roman scripts; and El Torito enables CDs to be bootable.

ISO 13490 is basically ISO 9660 with multisession support.

Operating System Support

Most operating systems support the reading of ISO 9660formatted discs, and most new versions support extensions such as Rock Ridge and Joliet. Operating systems that do not support the extensions usually show the basic (non-extended) features of a plain ISO 9660 disc.

The following are some operating systems and their support for ISO 9660 and the various extensions:

• DOS: access with extensions, such as MSCDEX.EXE (Microsoft CD-ROM Extension) or CORELCD.EXE

• Microsoft Windows 95, Windows 98, Windows ME: can read ISO 9660 Levels 1, 2, 3, and Joliet

• Microsoft Windows NT 4, Windows 2000, Windows XP: can read ISO 9660 Levels 1, 2, 3, and Joliet

• Linux and BSD: ISO 9660 Levels 1, 2, 3, Joliet, and Rock Ridge

• Mac OS 7 to 9: ISO Levels 1, and 2. Optional free software supports Rock Ridge and Joliet: Joke Ridge (www.alex-castro.com/jokeridge/) and Joliet Volume Access (www.tempel.org/joliet/)

You can use the Configuration Editor of your virtual machine to make this simple change (see Figure 8.1).

Figure 8-1. Changing Your Virtual Machine's CD-ROM

Drill down to where you keep your ISO image. In this example, we created a top-level directory called /vmlib (short for VMlibrary) and in that directory we have a subdirectory called iso_s. Browsing this directory, we can select our Windows 2003 Server, Enterprise ISO image, which this virtual machine will use as its CD-ROM (see Figure 8.2).

Figure 8-2. Selecting the ISO Image

Since this ISO image is an exact copy of the CD-ROM media from which it was taken and not just the files on the CD-ROM, this will be a bootable ISO image from which you can build your server (see Figure 8.3).

Figure 8-3. Building a Virtual Server

Once the path of your ISO image is populated, click OK. You may have to adjust the BIOS so the virtual machine uses its CD-ROM first in its boot order.

To create an ISO image using WinISO, you must first purchase it. It goes for a nominal cost of around $30. Once you have it installed, place the CD you want to make an ISO from into your CD-ROM (it's important to understand the difference between a bootable CD and autorun… In order to have your virtual machine boot from the ISO image, the original media must be bootable. To ensure this, use the original media).

From the Actions menu, select Make ISO From CD-ROM, or press the F6 key on your computer (see Figure 8.4).

Figure 8-4. Selecting Make ISO from CD-ROM from the Actions Menu

You'll be prompted for the path for the ISO, as well as its name. Give the ISO a clear namefor example, w2k3-ent-w-sp1.iso for an ISO image of a Windows 2003 Server, Enterprise Edition with Service Pack 1 slipstreamed into it. In our example, it's simply w2k3-ent.iso (see Figure 8.5).

Figure 8-5. Naming the ISO Image

Also, ensure that under Options you've selected ASPI. This allows you to make a bootable ISO.

Once the ISO image is created, you can move it onto your ESX Server using a tool like WinSCP. See the following WinSCP section for more details.