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Table Of Contents
Services that affect OS disk growth also generate input/output operations per second (IOPS) on the Windows
7 virtual machines. Disabling these services can reduce IOPS and improve performance on full virtual machines
and linked clones.
Disabling certain services also might benefit Windows XP and Windows Vista operating systems.
These best practices for optimizing Windows 7 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-clone
desktops. 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 Services and Tasks That Cause Linked-Clone Growth
Certain Windows 7 services and tasks can cause linked-clone OS disks to grow incrementally every few hours,
even when the linked-clone desktops 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 the Windows 7 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 services that are shown in Table 4-7, verify that you took the optimization
steps in “Optimize Windows Guest Operating System Performance,” on page 56 and “Optimize Windows 7
Guest Operating System Performance,” on page 57.
Table 4-7. Impact of Windows 7 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 66..
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
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