two technologies mentioned here are free, Microsoft-provided technologies.If you have multiple libraries, you will end up with the same content on many library
servers, and your templates will refer to the content on a specific library server. For
instance, a template might indicate a server in London, such as
\londonlib\SCVMM\VHDs\2008R2.vhd. But you are actually deploying to a server in
New York, and there is a library server in New York, \newyorklib\SCVMM, that has
exactly the same file, which you would rather use than copying the content over the
North Atlantic. SCVMM allows equivalencies to be created in the library, which as the
name suggests enables you to specify that various content from all of the libraries are
the same object. This means that even though a template may say to deploy
\londonlib\SCVMM\VHDs\2012R2.vhd, because you created an equivalency between the
\londonlib\SCVMM\VHDs\2012R2.vhd and \newyorklib\SCVMM\VHDs\2012R2.vhd files,
if you deployed the template in New York, it would use the VHD from the New York
share. This also provides redundancy because if the New York library is not available,
the London library can be used.
To create an equivalency, you select the root Library Servers node in the Navigation
pane in the Library workspace. You can then add a filter in the Results pane to show
the objects of interest. Select the objects that are the same and then select the Mark
Equivalent action; a dialog box opens that asks for a family for the objects and then a
release. Both of these values are text values used to help find other objects that match
the family and release, so be consistent in your naming. As you type in the values,
autocomplete shows existing values, or you can select from the drop-down.
One of the interesting ways that library content is used is via ISO files, which are files
that contain the content of a CD or DVD. To inject a CD/DVD into a virtual machine,
you access the properties of a virtual machine by selecting the VM in the Results pane
of the VMs And Services workspace and selecting the Properties action. Within the
properties of the virtual machine, you select the Hardware Configuration tab, and then
under Bus Configuration you select Virtual DVD Drive. Notice the option for No
Media, which means that the drive is empty. Physical CD or DVD Drive links the
virtual drive to the physical optical drive in the virtualization host, and Existing ISO
Image File allows you to select an ISO file from the library.
Notice an interesting option in Figure 9.6: Share File Instead Of Copying It. A
CD/DVD image is usually used to install software onto an operating system. If the VM
accesses an ISO file over the network and that connectivity is lost, unexpected results
may occur, because it would appear that the media was suddenly ripped out. To avoid
this from happening by default, when an ISO is attached to a VM drive, the ISO is first
copied using BITS over HTTPS to the Hyper-V host in the virtual machine’s folder, and
then the VM attaches to the local copied ISO file. Any network interruption would not
stop the access to the ISO. When the ISO is ejected from the VM, the copied ISO file is
deleted from the local host. Although this does use disk space while the ISO is being
used, it provides the safest approach. This same copy approach is used for ESX, but it