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Disable Prefetch, SuperFetch, And Windows Write-Cache Buffer Flushing

Can You Get More Space Or Speed From Your SSD?

Disable Prefetch and SuperFetch

How to disable:

  • Type Regedit into the Start menu's Search box

  • Select the file path "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SessionManager\Memory Management\PrefetchParameters"
  • Right-click on both EnablePrefetcher and EnableSuperfetch
  • Select Modify on each of these to change the value from 1 (or 3) to 0
  • Restart

SuperFetch is designed to cache files used often. Given the low access times of SSDs, this option can be disabled. If you installed Windows 7 on an SSD, it should, in fact, be disabled automatically.

Prefetch loads pieces of program files into RAM. By disabling this feature, you free up your system memory.

Disable Windows Write-Cache Buffer Flushing

This is one of those tweaks that isn't universal to all SSDs. In fact, it's not recommended if you own an Intel drive, as it purportedly has a negative impact on performance. If anything, take note of your storage subsystem's performance before and after this alteration to determine if it's something you really want to use or not.

How to disable:

  • Right-click Computer in the Start menu, then select Properties
  • Select Device Manager
  • Select Disk drives
  • Right-click your SSD and select Properties
  • Under the Polices tab, check the Turn off Windows write-cache buffer flushing on the device box

Per Windows Help, "Write caching in a storage device refers to the use of high-speed volatile memory to collect write commands sent to data storage devices and cache them until the slower storage media (either physical disks or low-cost flash memory) can accommodate them."

In the case of a hard drive, the operating system flushes commands to a disk's on-board cache. That doesn't mean it's safe yet, though. So, it waits for the drive to report back that cached data has been written to the magnetic media. If you're more concerned with performance than the integrity of your data, turning off write-cache buffer flushing skips that extra command to flush the internal RAM buffer. 

For a more detailed explanation of flushing and the risks associated with turning it off, check out Microsoft employee Raymond Chen's personal blog post on the topic.

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