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

Can You Get More Space Or Speed From Your SSD?
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With the market for solid-state drives continually expanding, we wanted to explore some of the most popular tweaks enthusiasts use to purportedly improve performance and free up capacity. We break out the benchmarks and put them to the test.

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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  • 10 Hide
    Anonymous , June 9, 2011 6:44 AM
    Indexing is not used to access files more quickly. It's used to find files more quickly in search. Disabling indexing will result in slower searching.

    Hibernation: Amount of space saved by turning this off is equivalent to the amount of RAM in your system. Not limited to 2GB.

    Also, hibernation has benefits over standby where hibernation will allow your system to return to a fully working state after removing power whereas standby requires power to still be supplied to your system. Laptops for example you'll want to hibernate to avoid discharging the battery while in sleep mode.
Other Comments
  • 10 Hide
    Anonymous , June 9, 2011 6:44 AM
    Indexing is not used to access files more quickly. It's used to find files more quickly in search. Disabling indexing will result in slower searching.

    Hibernation: Amount of space saved by turning this off is equivalent to the amount of RAM in your system. Not limited to 2GB.

    Also, hibernation has benefits over standby where hibernation will allow your system to return to a fully working state after removing power whereas standby requires power to still be supplied to your system. Laptops for example you'll want to hibernate to avoid discharging the battery while in sleep mode.
  • 8 Hide
    compton , June 9, 2011 7:01 AM
    With system restore disabled, no swap file, and some of the additonal tweaks mentioned here, my two small capacity SSD's are running Win 7 effectively in a small footprint -- my 60GB Agility has 37GB free, while the X25-V in my laptop has over 20GB free. The best part is keeping lots of extra space help longevity, while the tweaks enhance performance while keeping my drives free of junk.

    Thanks for another excellent article -- I'm surprised I haven't seen an article on this subject that's as comprehensive. Toms to the rescue.
  • 3 Hide
    anttonij , June 9, 2011 7:08 AM
    Thanks for another great article. I would love to see a part 2 of the article where you would explore the causes of the performance drop.
  • 1 Hide
    cangelini , June 9, 2011 7:26 AM
    KWReidIndexing is not used to access files more quickly. It's used to find files more quickly in search. Disabling indexing will result in slower searching.Hibernation: Amount of space saved by turning this off is equivalent to the amount of RAM in your system. Not limited to 2GB.Also, hibernation has benefits over standby where hibernation will allow your system to return to a fully working state after removing power whereas standby requires power to still be supplied to your system. Laptops for example you'll want to hibernate to avoid discharging the battery while in sleep mode.


    Thanks for pointing both of these things out. You're absolutely correct about indexing.

    I've updated the story for the author to reflect hibernation as well. I added clarification re: desktops and notebooks, though I'd suggest powering down a notebook with an SSD is comparable to putting it into hibernation. I don't think anyone would recommend putting it into standby; as you mention, that continues to drain power.

    All the best!
    Chris
  • 3 Hide
    HalfHuman , June 9, 2011 9:57 AM
    the article is very useful.
    disabling system rstore is usually a good idea, sometimes it's better to just limit it's size form the 10% default value.
    swap disabling is not a good idea, as you said. i'd rather have the swap on a secondary, mechanical drive.
    indexing is very useful. you can relocate the address to where indexing data is stored. i put it on a mechanical drive.
    disabling superfetch and turbo cache are really useful. ssd may be faster than hdd, but they are weak compared to ram speed. read caching really makes a difference.
    hibernation file is not really useful on a desktop but it's a matter of taste. better have it on a mechanical drive if possible
    another thing that really helps is putting firefox profiles on a ram drive. i develop on visual studio and there is a directory where lots of small files are written on build. having this temp folder on a ramdrive helps a lot regarding speed and writes as well.
  • 4 Hide
    HalfHuman , June 9, 2011 10:00 AM
    oops... i meant having windows superfect and turbo cache (not sure about actual names) active is really useful. the memory that is occupied by caching gets liberated quickly if it's needed by apps. in the mean time it can really help on read caching.
  • 0 Hide
    ravewulf , June 9, 2011 10:20 AM
    None of my controllers mention AHCI, but my motherboard is set to use AHCI. I do see "AMD SATA Controller," is that it? I also don't see any ATA Channels as in the screen shot, just two IDE channels with no devices on them. I don't have an SSD, so no need for TRIM, but I would like to verify that I'm using AHCI.
  • 1 Hide
    nyrychvantel , June 9, 2011 11:22 AM
    This article is excellent for those SSD users who have just installed/reinstalled their OS. I will also forward this article to all my friends using SSD.
  • 4 Hide
    haplo602 , June 9, 2011 12:46 PM
    who came up with that idiot description of hibernation ? it was invented to:

    1. save power
    2. restore the previous work withou having to start everything

    I use hibernation a lot on my desktop just because I can leave all the network independent applications running and just power down. after power up, I am in the previous environment state and can immediately continue whatever I was doing before. No need to start applications and reopen saved files.
  • 3 Hide
    jaquith , June 9, 2011 12:49 PM
    Excellent article and I agree with most of Doug's solid advice. However, as a compromise I would recommend that users reduce the System Restore SIZE versus turning it off all together. System Restore would not be needed in a 'perfect' world, but reformatting or reinstalling windows is a tough trade-off.
  • 1 Hide
    jaquith , June 9, 2011 1:17 PM
    ...Also, if you are using a monitored UPS {Uninterrupted Power Supply} you must leave Hibernation turned-on. Once the battery hits its' minimum, typically 10% it triggers Windows to go into Hibernation mode to prevent data loss.
  • 2 Hide
    JackNaylorPE , June 9, 2011 1:26 PM
    No mention of relocating User File locations ? ..... this, by far, exceeds all of the above "space savers" combined. Checked the size of your e-mail inbox / sent box lately ?

    http://www.sevenforums.com/tutorials/124198-user-profiles-create-move-during-windows-7-installation.html
  • 3 Hide
    chesteracorgi , June 9, 2011 1:46 PM
    Nice review, but a little late to the game:

    http://thessdreview.com/ssd-guides/optimization-guides/the-ssd-optimization-guide-2/

  • 3 Hide
    tecmo34 , June 9, 2011 2:00 PM
    @jaquith... You bring up good and valid points on System Restore and hibernation with a UPS in play.

    @JackNaylorPE... This another very good point on moving USER folder to another drive. It does free up additional space and keep down on writes.

    @Chesteracorgi... There are many threads on tweaking, as the The SSD Optimization Guide is a very good one. The purpose of my article was not necessarily on what tweaks needed to perform but what actual benefits do you receive from performing them.
  • 1 Hide
    Duskfall , June 9, 2011 2:02 PM
    If i do the ahci setting in my controller or the registry setting which as I see is a universal setting in windows,wont it affect my other HDD's performance which aren't SSD's??
  • 1 Hide
    cknobman , June 9, 2011 2:34 PM
    This is one of the most useful articles I have ever read here on Toms. Thanks for doing this and I look forward to seeing many more useful articles like this!!!!!!!!!!!!!!!!!!!!!!!!!!!
  • 0 Hide
    wolfram23 , June 9, 2011 2:51 PM
    Awesome SSD article. Goes over some points I already knew, but it's now in one easy to find place!

    Also I have a suggestion. For example with System Restore and File Paging, you should make mention that you can simply apply them to your storage HDD instead of the SSD.

    Oh and what's the point of telling us to disable Prefetch, which has no effect on the SSD and can certainly help the system stay faster by preloading onto RAM? Plenty of enthusiasts have 6, 8, or 12 gigs of RAM so it's not like space is a premium...
  • 0 Hide
    scook9 , June 9, 2011 3:03 PM
    Disable disk defragmenter.....
  • 0 Hide
    ravewulf , June 9, 2011 3:23 PM
    scook9Disable disk defragmenter.....

    Windows 7 does that by default for SSD's
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