6.0

These best practices for optimizing Windows 7 and Windows 8 apply to most user environments. However,
you must evaluate the effect of disabling each service on your users, applications, and desktops. You might
require certain services to stay active.
For example, disabling Windows Update Service makes sense if you refresh and recompose the linked
clones. A refresh operation restores the OS disks to their last snapshots, deleting all automatic Windows
updates since the last snapshots were taken. A recompose operation recreates the OS disks from a new
snapshot that can contain the current Windows updates, making automatic Windows updates redundant.
If you do not use refresh and recompose regularly, you might decide to keep Windows Update Service
active.
Overview of Windows 7 and Windows 8 Services and Tasks That Cause Linked-
Clone Growth
Certain services and tasks in Windows 7 and Windows 8 can cause linked-clone OS disks to grow
incrementally every few hours, even when the linked-clone machines are idle. If you disable these services
and tasks, you can control the OS disk growth.
Services that affect OS disk growth also generate IOPS on Windows 7 and Windows 8 virtual machines. You
can evaluate the benefits of disabling these services on full virtual machines as well as linked clones.
Before you disable the Windows 7 or Windows 8 services that are shown in Table 3-9, verify that you took
the optimization steps in “Optimize Guest Operating System Performance for All Windows Versions,” on
page 34 and “Optimize Windows 7 and Windows 8 Guest Operating System Performance,” on page 35.
Table 3‑9. Impact of Windows 7 and Windows 8 Services and Tasks on OS Disk Growth and IOPS When OS Is Left
Idle
Service or Task Description
Default
Occurrence or
Startup
Impact on
Linked-Clone OS
Disks Impact on IOPS
Turn Off This
Service or Task?
Windows
Hibernation
Provides a power-
saving state by
storing open
documents and
programs in a file
before the
computer is
powered off. The
file is reloaded
into memory when
the computer is
restarted, restoring
the state when the
hibernation was
invoked.
Default power-
plan settings
disable
hibernation.
High.
By default, the size
of the hibernation
file,
hiberfil.sys, is
the same as the
installed RAM on
the virtual
machine. This
feature affects all
guest operating
systems.
High.
When hibernation
is triggered, the
system writes a
hiberfil.sys file
the size of the
installed RAM.
Yes
Hibernation
provides no benefit
in a virtual
environment.
For instructions, see
“Disable Windows
Hibernation in the
Parent Virtual
Machine,” on
page 46..
Windows
Scheduled Disk
Defragmentation
Disk
defragmentation is
scheduled as a
background
process.
Once a week High.
Repeated
defragmentation
operations can
increase the size of
linked-clone OS
disks by several
GB and do little to
make disk access
more efficient on
linked clones.
High Yes
Chapter 3 Creating and Preparing Virtual Machines
VMware, Inc. 37