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Disable Prefetch (Standard 7 SP1)

5/15/2014

Enhanced Write Filter (EWF) performance can sometimes be improved by disabling Prefetch. Prefetch is a tool that is intended to improve Standard 7 and application startup performance. It does this by loading application data into memory before it is demanded.

When you are using EWF with a RAM overly to protect the boot volume, Prefetch is unable to persist its data from startup to startup. Under these conditions, Prefetch tries to compute and save new data files every time that the system starts using EWF resources with, potentially, no benefit.

  • Update the EnablePrefetcher registry key in your run-time image:

    Key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters

    Name: EnablePrefetcher

    Type: REG_DWORD

    Value: 0

The EnablePrefetcher key has the following values:

0 = Disabled

1 = Application start prefetching enabled

2 = Boot prefetching enabled

3 = Application start and boot enabled

To disable Prefetch, set the value to 0.

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