Enable or Disable Write-Caching for an SSD?

Discussion in 'hardware' started by berryracer, Mar 31, 2012.

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  1. berryracer
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    berryracer Suspended Member

    I read somewhere that it is recommended to disable "Write Caching" if you have an SSD because SSDs don't have a cache or something like that

    Is that true? what is the best of course option? Leave it checked (default option) or disable it?

    How does this affect performance? Will it increase or decrease performance or would it have no effect?

    Attached Files:

  2. Mrkvonic
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    Mrkvonic Linux Systems Expert

    From my experience ...

    Leave default settings as is.

    Write cache is a nice thing for short-duration burst writes. For continuous data writes, it makes no difference. In general, you will not notice much.

    If you use UPS, then you can disable write cache with some degree of safety.

    Cheers,
    Mrk
  3. berryracer
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    berryracer Suspended Member

    But what about the claim that I heard that SSDs don't even have a write cache buffer and thus it would make no sense to keep it on?
  4. Mrkvonic
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    Mrkvonic Linux Systems Expert

    It makes no difference then.
    As to whether your drive has write cache, I do not know.
    Mrk
  5. Keatah
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    Keatah Registered Member

    This option pointed out in the graphic is an Operating System level function. It has nothing to do with the internal cache mechanisms of the storage device itself.

    It won't improve large streaming transfers in any case, but, it will improve small write operations speed. You will see an improvement on Spinners, and less of an improvement on Solids. Keep it active.
  6. Keatah
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    Keatah Registered Member

    You mean the opposite. If you use UPS then you can ENABLE the cache with some degree of safety.

    IMHO, unless you are prone to forcibly turning off your system by pulling the plug or live in an area with daily outages then this isn't much of a concern. In any case if those are problems then you need to address them in a completely separate way and not worry about this option in the first place.

    1- Learn how to turn off the computer correctly.
    2- Buy a UPS battery backup.
  7. NGRhodes
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    NGRhodes Registered Member

    If a drive does not support write caching how can enabling the option make a difference -its like flicking the switch on a light with no bulb fitted.
  8. NGRhodes
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    NGRhodes Registered Member

    Wrong.

    It is the devices internal buffer/cache:
    http://msdn.microsoft.com/en-us/library/windows/hardware/ff563944(v=vs.85).aspx
    http://msdn.microsoft.com/en-us/library/windows/hardware/ff567017(v=vs.85).aspx

    File caching is also done and is seperate:
    http://msdn.microsoft.com/en-us/library/windows/desktop/aa364218(v=vs.85).aspx

    Cheers, Nick
  9. NGRhodes
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    NGRhodes Registered Member

    Yes.
    Windows uses write barriers which does reduce effectiveness of write caching, but helps keep the data in sync with the meta data - extremely rare cases will you kill your file system due to an unclean shutdown. You essentially get a lot of reliability back for only a little performance loss.

    If you check the sub option in the first screen shot it disables the write barriers and increases the risk of lost data if you don't have battery backup.

    Cheers, Nick
  10. xxJackxx
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    xxJackxx Registered Member

    If your drive supports it then the checkbox to enable it will be enabled and you can select if you want to use caching or not. If your drive does not support it, then the checkbox will be disabled and you will not be able to enable caching. On an SSD you won't notice much difference, feel free to experiment and see what gives the best results. I do not recommend turning it on without a battery backup. A laptop with a battery in it will work as well. There are many SSD optimization guides out there. Ignore them, they are pretty useless. Most of what they recommend will rob you of the performance increase you get by buying an SSD in the first place. o_O
  11. Keatah
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    Keatah Registered Member

    @nick - Agreed.

    @xxJackxx Also agreed. I believe many of these optimization guides are done as busy makework. A reason for a site to exist. I once tweaked a system up, a long long time ago, and ended up not really gaining much if anything. What I did gain were slowdowns for some apps and most certainly system instability.

    This one system eventually got "untweaked" over the course of a few weeks by restoring and undoing all the hacks and mods. And I made sure it stayed that way from then on.

    Many of these so-called tweaks and killing-off-processes guides result in one niche area gaining a couple of percent extra performance, perhaps, at the expense of other things becoming unstable or buggy nor simply not working fast or "right". Somehow.

    So far I'm not impressed with accelerator programs and game mods or even some of these extra disk caching packages. Let alone registry tweakers and crap like that.
  12. xxJackxx
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    xxJackxx Registered Member

    I think back a decade ago when I started using XP on a new build and was trying all of the tweak guides and was stupid enough to use the "LargeSystemCache" tweak at the recommendation of so many sites. I ended up trashing my Windows install 3 times in 2 weeks before I figured out what it was.
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