VMware View Manager 4.5 Admin Manual page 85

Recomposing Linked Clones Customized with Sysprep
If you recompose a linked-clone desktop that was customized with Sysprep, View Manager runs the Sysprep
customization specification again after the OS disk is recomposed. This operation generates a new SID for the
linked-clone virtual machine.
If a new SID is generated, the recomposed linked clone functions as a new computer on the network. Some
software programs such as system-management tools depend on the SID to identify the computers under their
management. These programs might not be able to identify or locate the linked-clone virtual machine.
Also, if third-party software is installed on the system disk, the customization specification might regenerate
the GUIDs for that software after the recomposition.
A recomposition restores the linked clone to its original state, before the customization specification was run
the first time. In this state, the linked clone does not have a local computer SID or the GUID of any third-party
software installed in the system drive. View Manager must run the Sysprep customization specification after
the linked clone is recomposed.
Storage Sizing for Linked-Clone Desktop Pools
View Manager provides high-level guidelines that can help you determine how much storage a linked-clone
desktop pool requires. A table in the Add Pool wizard shows a general estimate of the linked-clone disks'
storage requirements when the pool is created and as the linked clones grow over time.
The storage-sizing table also displays the free space on the datastores that you select for storing OS disks, View
Composer persistent disks, and replicas. You can decide which datastores to use by comparing the actual free
space with the estimated requirements for the linked-clone disks.
The formulas that View Manager uses can only provide a general estimate of storage use. Your linked clones'
actual storage growth depends on many factors:
Amount of memory assigned to the parent virtual machine
n
Frequency of refresh operations
n
Size of the guest operating system's paging file
n
Whether you redirect paging and temp files to a separate disk
n
Whether you configure separate View Composer persistent disks
n
Workload on the linked-clone desktops, determined primarily by the types of applications that users run
n
in the guest operating system
N In a deployment that includes hundreds or thousands of linked clones, configure your linked-clone
OTE
pools so that particular sets of datastores are dedicated to particular ESX clusters. Do not configure pools
randomly across all the datastores so that most or all ESX hosts must access most or all LUNs.
When too many ESX hosts attempt to write to linked-clone OS disks on a particular LUN, contention problems
can occur, degrading performance and interfering with scalability. For more information about datastore
planning in large deployments, see the VMware View Architecture Planning Guide.
Sizing Guidelines for Linked-Clone Pools
When you create or edit a linked-clone desktop pool, the Select Datastores page displays a table that provides
storage-sizing guidelines. The table can help you to decide which datastores to select for the linked-clone disks.
Sizing Table for Linked-Clone Disks
Table 5-7 shows an example of storage-sizing recommendations that might be displayed for a pool of 10 virtual
machines if the parent virtual machine has 1GB of memory and a 10GB replica. In this example, different
datastores are selected for OS disks and View Composer persistent disks.
VMware, Inc.
Chapter 5 Creating Desktop Pools
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