Windows ReadyBoost

Windows ReadyBoost

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If there is one thing that can really help applications on Windows Vista run better, it's memory.  When comparing the performance of Windows XP and Windows Vista on a PC with 1 GB of main memory, Windows Vista is generally comparable to Windows XP or faster.  However, we also know that in some cases, on PCs with 512 MB of main memory, applications on Windows XP may seem more responsive.  Why?  Mostly because the features in Windows Vista use a bit more memory to do the things that make it so cool, like indexing your data, keeping the fancier AERO UI running using the desktop window manager (DWM), etc.  The less memory in your machine, the more often the OS must randomly access the disk.  This slows system performs in cases where your applications just barely fit in memory on Windows XP but not quite in Windows Vista.

We redesigned the memory manager in Windows Vista so that if you give the system more memory, it uses that memory much more efficiently than previous operating systems via a technique called SuperFetch -- part of Windows Vista's intelligent heuristic memory management system.  And so Windows Vista on a PC with even more than 1 GB of primary memory (say 2 GB) will generally outperform Windows XP on that same machine -- especially once you have been using the machine for some time because Windows Vista learns what you do the most often and optimizes for this.

While I fully expect the generation of PCs that ship with Windows Vista to include more memory, we also know that many existing PCs have 512 MB.  While memory has gotten much less expensive, many (non-geek) people I know are just not comfortable opening up their PC and installing more memory.  While there are some great PC shops that will do this for you, a lot of people may not want to bother.  Well with Windows ReadyBoost, if you have a flash drive (like a USB thumb drive or an SD card) you can just use this to make your computer run better with Windows Vista.  You simply plug in a flash drive and Windows Vista will use Windows ReadyBoost to utilize the flash memory to improve performance.

I should be clear that while flash drives do contain memory, Windows ReadyBoost isn’t really using that memory to increase the main system RAM in your computer.  Instead, ReadyBoost uses the flash drive to store information that is being used by the memory manager.  If you are running a lot of applications on a system that has limited memory, Windows ReadyBoost will use the flash drive to create a copy of virtual memory that is not quite as fast as RAM, but a whole lot faster than going to the hard disk.  What is very cool here is that there is nothing stored on this flash disk that isn’t also on the hard disk, so if you remove the flash drive, the memory manager sees the change and automatically goes to the hard disk.  While the performance gain from ReadyBoost is gone, you don’t lose any data and there is no interruption.  And because the Windows Readyboost cache on the flash drive is encrypted using AES-128, you don’t need to worry about exposing sensitive data if the flash drive is stolen or lost.  Also, the memory manager compresses the pages before writing them into the cache on the flash disk, which means you’ll get more mileage from each MB.

So, if you just want your PC to run faster with Windows Vista -- it's pretty simple -- connect your flash drive through any USB 2.0 socket or PCI interface and when the autoplay interface comes up, choose "Speed up my system using ReadyBoost."  You need to have at least 230 MB free on the flash drive and some flash disks are not fast enough to support Windows ReadyBoost, although you’ll be told if that's the case.

If you want to learn more about ReadyBoost, Matt Ayers, the program manager for ReadyBoost, created a great FAQ that Tom Archer posted on his blog that is really worth reading.  Tom also did a great job of showing all of the set-up screens in his blog.

If you are like me, you may have a few flash drives in your desk.  If not, you can buy 1 GB drives online for less than $50.  If you put a flash drive into a Windows XP PC, you get access to files on the drive -- if you add that same drive to an identical machine running Windows Vista, you can also boost the performance of your PC with ReadyBoost.  Just one more way that Windows Vista helps you get the most from your hardware.


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  • well jimall you have shared a very vital info with us! i appreciate it.

  • kamidan
    1 Posts

    I've got Windows Vista 64Bit (it came on this computer, if it were my choice I would have installed 32bit) and 4GB of RAM.

    Today I found a nice deal on a 16GB flash drive that is window vista readyboost compatible, so I inserted it into one of the USB 2.0 slots in the back of my computer (was interesting to find out the convienience usb ports on the top of my computer are only 1.x usb) and got the readyboost dialog.

    Going by what the author wrote on this page, I should use between 4090 and 8GB of the 16GB flash drive for readyboost, however for some reason Windows is only allowing me to use a maximum of 4090 so the remainder of the 12GB is pretty much wasted as it was only bought so that I could use 8GB for readyboost.  I guess I could have gotten away with buying the 4GB for a lot less money.

    Any clues how to get windows to use 8GB readboost?  Or is 4GB the absolute maximum readyboost will use?

  • Duane Duane
    52463 Posts

    I just purchased a Corsair Voyager 4GB pen drive exclusively for Vista's ReadyBoost, and I'm pretty much impressed by the extra speed my notebook gained from it. [Using a 1.9ghz duo with 2GB DDR2] ^_^

  • I am using readyboost with Sandisk cruzer mini. Annoying thing is that every time I boot I have to  remove the disk as Vista attempt to boot from it. Can not we have a minimum boot with a redirector in the USB disk along with paging file so that it boots from the drive and then automatically use hard drive as the full booting. Don't want to fiddle with boot devices in BIOS

  • I have a 4GIG ram on my laptop and I have installed windows Vista Ultimate.

    Is it still possible to add more RAM to my box using readyboost?

  • ReadyBoost is an excellent idea and one that I'd like to see utilised in other OS platforms!

  • Rather than having a flash drive for ReadyBoost sticking out of the back or front of our computer cases using the standard USB sockets, it would seem prudent for motherboard manufacturers to include an internal USB socket so that a flash drive for ReadyBoost can be permanently mounted vertically on the motherboard inside the case where it will be safe and not unsightly.  

  • vfxtodd
    1 Posts

    I just got a Toshiba laptop with 1GB of RAM and I've ordered a 4GB USB drive (made for Vista). Can anyone tell me if there is a way to measure how much "faster" my machine will be using ReadyBoost with the 4GB drive?

  • I have described on my blog a cool trick for using Readyboost with flash drives that might not otherwise meet Vista's requirements.


  • Nick White
    1204 Posts

    Hey destin5488:  it'll depend on the transfer rate of both the card (or USB drive) and the speed of the bus connecting to it.  Some cards/drives are faster than others -- it really depends on the unit's specifications.  In any case, any performance boost you'd see is likely to be negligible.

  • I have a built in SD card ready and readyboost works well with a 2GB SD card. My transfer rate for the card is about 4 mb/s, would a USB drive have better performance?

  • Inkling
    1 Posts

    Just thought you'd like to know that I'm so impressed with ReadyBoost and the comments in its favor, that I posted a suggestion to Apple that they add it to 10.5 ASAP.

    Anyone who'd like to add their vote to mind can do so at:

    What was it Steve Jobs said about "Mediocre minds borrow, brilliant minds steal." This is an idea Apple needs to "steal" from Vista. Cross-fertilization is good for both companies.

    --Mike Perry, Author of Untangling Tolkien

  • Hey "Jim Allchin",thx for share


  • ReadyBoost only works with fast Flash Drives. I’ve tried about 4 different ones and none of them worked on my PC. Good news is they aren’t that expensive. I found a website that shows 20+ flash drives that are Vista/ReadyBoost compatible. The site is called and all the products are

    from They have flash drives from 512MB to 8GB. I use this site b/c it has a tested list of flash drives. TigerDirect doesn’t give you a ‘Vista compatible’ search option. This site is the next best thing as it lists only tested thumb drives and directs you to them on Perfect. This way I know I’m dealing with a reputable company like Tigerdirect.

    Good luck all. Hope you enjoy Vista.

  • vic
    1 Posts

    Hi guys,

     I am trying to find a way to measure the performance of my usb device with ReadyBoost technology. I share my procedure and welcome any discussion.

    System Memory : 512 MB

    Flash device size : 1 GB(All for ReadyBoost)

    1.Start Vista.

    2.Run some applications. (see below)

    3.Run Windows Mail and measure the time of start-up.

    4.Plug-in USB device and wait Vista to cache.

    5.Maximize Windows Media Center then restore it down.(Prevent memory still contain cache of Windows Mail.)

    6.Run Windows Mail and measure the time of start-up again.

    You should see the improvement.

    w/o ReadyBoost : 44 Secs.

    with ReadyBoost : 14 Secs.

    **This measurement can only measure the roughly performance of ReadyBoost with my USB device.**

    ==== The applications at step 2 ======

    Windows Media Center

    Windows Photo Gallery

    Windows Contacts

    Windows Update

    Windows DVD Maker

    Windows Calendar

    Windows Defender

    Windows Fax and Scan

    Windows Movie Maker

    Windows Media Player

    Default Programs

    IE x 30

    Game - Chess Titans

    Game - FreeCell

    Game - Hearts

    Game - Mahjong Titans

    Game - Minesweeper

    Game - Purble Place

    Game - Solitaire

    Game - Spider Solitaire

    Accessories - WordPad

    Task manager


  • cisco
    1 Posts

    I noticed that when i put in my 2GB stick it seems to peg the cpu more. I have an AMD Sempron 2800+(1.6ghz) and 1 Gig of ram.  It *seems* like it actually runs faster without the drive because of the cpu going up.  I just received the drive today. (cruzer 2GB)

  • Nick White
    1204 Posts

    Hey VistaIsMyLove:  take a look at the FAQ mentioned in the post above (, as it will answer your question better than I can -- namely:

    Q: Isn't this just putting the paging file onto a flash disk?

    A: Not really - the file is still backed on disk. This is a cache - if the data is not found in the ReadyBoost cache, we fall back to the HDD.

    Hope this helps.  

  • Hi

    ReadyBoost is really Cool and useful BUT I have a question ???

    If I unplug my flash suddenly !?? How Vista can keep my data a live ??

    O.K , if we say that the flash contains ONLY a COPY So, How Windows Vista continuously updating he two sides ? the Flash and The Hard Disk ??

    BUT Vista is My Next Cool,productive OS ....


  • Laurent
    5 Posts

    ReadyBoost is really a great feature !!!

  • Nick White
    1204 Posts

    Hey egbet:

    I've conferred with my colleagues and they've asked me to relay the following responses to you:

    1) Probably not one that would be readily noticeable to typical end-users.  The ReadyBoost cache is really separate from physical memory, and thus is protected when important file pages are pushed out of memory.  Here’s an example: let’s say you have a technical computing application that uses 15GB of physical memory for its purposes.  That would leave 1GB or so for the rest of what you might want in memory.  In this case, the ReadyBoost cache may help in that it may have some cached pages you really wish were still there.  How well this works in practice depends on a number of factors including the I/O patterns for those files and the size of the file set.

    2) We don’t allow compression on/off to be controlled.  

    3) We don’t support multiple devices in this release, although it is something we’re exploring for the future.

    4) ReadyDrive based hybrid drives are coming, but this is different from ReadyBoost.  We’ve built in support for ReadyDrives in Windows Vista and major drive manufacturers have already announced products that will be in the market in 2007.  Due to cost scaling, we expect it will be quite awhile before the non-volatile cache sizes in these devices get anywhere near 16GB for mainstream customers.

  • egbet
    1 Posts

    1. Say you are running Vista on a machine with 16GB FB-DIMM and no pagefile. Would there be a performance increase using ReadyBoost?

    2. If someone has a 16GB flash drive, can the ReadyBoost compression be turned off for better performance and would it make a difference?

    3. If I use four really fast 2GB flash drives on USB2.0, will ReadyBoost be able to use all four drives like you can split the pagefiles?

    4. I see the progression of this technology. How long do you think it will take the industry to get HDD w/Flash to market? Or even Mobos with 16-32GB flash caches on them?

  • 1GB of ReadyBoost on an elderly Tosh tablet makes a big difference - not just to performance but we're finding it gives an extra ~15 minutes of battery life. I was surpised how few of the flash sticks we've tried have been fast enough - we have quite the stash - and RTM hasn't made a big difference there, but I'm not quibbling about that because this needs to be near-memory speeds.

    I have a note from one MS event where they calculated life of a stick for ReadyBoost at anything from 16 to 1800 years based on the read/write cycle. 10 sounds fair...

    My wish for Vista SP/Fijii would be to allow more than one ReadyBoost stick on a PC at once, aggregated through a hub perhaps ;)

  • bluvg
    15 Posts

    re: 64-bit--other than the hi-performance/scientific computing world, enabling 64-bits for GUI apps is quite important... perhaps even more important for the Mac user base (Photoshop-heavy) than for the Windows user base.  But more importantly, the Cocoa and Carbon APIs aren't 64-bit (yet).  This is actually similar to the Alpha days--the Win32 (uh, the 32 part should give it away!) APIs weren't 64-bit.  64-bit programming was possible on Alpha, but messy at best.  Considering the cost of RAM at the time (not to mention the demand/maturity of NT at the time for such tasks), that wasn't a disappointment for many people! ;)

    In reality, I think you're right, though--essentially, we're just witnessing the dawn of the 64-bit era for consumers on both platforms.

  • Alright, I'm a longtime Windows (since 2.0/286) and Mac (since System 6.0.3) user.  I think Vista will be the best upgrade ever, even or better than OS X Tiger in most ways.  But I still think OS X Leopard will be better in most ways.

    As for the comparison, yes, you need to compare to Quartz 2D Extreme, which is not enabled yet.  And that DOES require as much horsepower as Aero requires.  And, Aero Glass looks MUCH better (from a tech-geek perspective, not necesarily from a usability perspective.)

    As for the 64-bit question?  OS X has had the ability to execute 64-bit processes since 10.2.8 that came out with the Power Mac G5 in 2003.  The GUI apps couldn't be 64-bit; but in modern programming, that isn't exactly a glaring limitation.  And Windows NT 4.0 and 2000 on Alpha were still only 32-bit.  The CHIP may have been capable of 64-bit operation, but Windows only ran it in 32-bit mode.  Windows XP 64-bit Edition for the Itanium was the first 64-bit release of Windows.

    But, for all intents and purposes, Vista and Leopard will be the first MAJOR releases of both OSes to be 64-bit.  (Sorry, XP Professional for x64 systems doesn't qualify.  It is just an extended public beta, much like Apple did with OS X before version 10.0 came out.)

  • bluvg
    15 Posts

    RyanLM--I have tested Vista on both nVidia and ATI cards, and from personal experience can say that the nVidia drivers are just not very solid yet (although the latest are much better than earlier releases).  I had much better results with ATI cards, so I think your suspicion of the nVidia drivers is correct.

    BTW--are you using two nVidia cards?  Were they driving those two 30" Apple displays with single or dual cards?  I tried out a quad-core Mac Pro + a single 30" display at Microcenter two weeks ago, and it seemed to me that window resizing was still not silky-smooth (though the text re-rendering was appropriately fast).  I certainly wouldn't turn one down, though. ;)  And those 30" and 24" Dells are too much for your setup, I know someone that could put them to use. :D

  • Nick White
    1204 Posts

    Hey ack1949:  glad to hear it!  I use ReadyBoost whenever I have a USB key handy.

  • RyanLM
    11 Posts

    "At any rate, from 10,000 feet, yes, it looks like Vista requires more to do what OS X is already doing.  But dig a little deeper, and you'll see that not only is Vista more advanced "under the hood," the requirements for both Vista and OS X (Quartz 2D Extreme enabled to compare the two more evenly) are more or less the same."

    It isnt just a more resource question, it is that it sucks :) I have RTM code, and after using it for another week, it starting to suck.  I am hopeful that newer nVidia drivers will fix some of the issues - but it is not going to fix all of them.  I then thought, hey - maybe it is because I have a 30" Dell display, and another 24" Dell, maybe a Quadro with a speedy Dualcore Athlon isnt enough to power it.  However, over the holiday weekend I stopped at an Applestore, they had one PC with two 30" and it was as smooth as glass with every applciation I could open.

    I also took some time to look window resizing while I was there.  It is basically perfect, MS should just copy whatever it is they are doing - no tearing, no window redrawing, no glass turning black, it just resizes as a whole.  

    Also, while I can respect that Apple has had several releases to improve their GUI, MS has taken the same ammount of time to prepare vista.  This is sorta like the PS3 vs Xbox360 arguements out there that the PS3 keeps losing, you cant come out late and have less polish than a competitor and expect a grace period to get yourself ready for prime time.

  • sc0ri0n
    2 Posts

    I have not tested this yet but it's a very cool idea!

  • ack1949
    1 Posts

    Just for grins, I purchased an Apacer HT203 4GB USB Handy Steno w/Dock - 200x Speed ( to test ReadyBoost.

    To make a long story short, it DOES make a difference. I have 4GB DDR2 RAM in my Vista machine (64-bit) and the addition of the USB drive made EVERYTHING run  MUCH faster. I'm impressed. Keep up the good work!

  • to someone :

    Faq at link above claims 10 years .

  • someone
    156 Posts

    Please tell me honestly approximately how long will a Flash memory drive designed for ReadyBoost last.

  • if ,when writing data to flashmem , vista encrypts and compresses data , doesn't this increase the cpu usage considerably?

    Apple doesn't code a whole OS , it's FreeBSD with tweaks and apple eye candies.

    Apple doesn't make hardware too, its almost a pc hardware. Apple does produce mp3 players and they are very good at marketing.

  • Inkmaster... one does have to ask... ever since the G5 Mac has had 64-bit hardware, but yet no 64-bit OS...

    Microsoft has had one since the days of the Alpha.

  • bazanime
    13 Posts

    I like vista. I really love the way it runs even quicker than XP on my dual boot machine, with similar amount of applications.

    So, i know its vast improvement.

    I just think the team should work very close with the osx team and OPEN THEIR MINDS to other ideas.

    Its not easy to do this, 50 million lines of code is no small stuff and i commend them immensely for that.

    Btw...i really love the sidebar. please work on more first party "gadgets" and encourage third parties to create more.

    I'll be picking up the full Vista Ultimate on the 30th.  

  • bluvg
    15 Posts

    Ink Master, bazanime, RyanLM: You're comparing apples and oranges (groan, I know!).  If you look at OS X, the graphics technologies it uses have evolved gradually over several releases, whereas Vista is a large leap over that which was available in XP.  For example, Quartz Extreme--the technology you're talking about, which requires 16 MB of VRAM, 32 MB recommended--wasn't introduced until 10.2, and Quartz 2D Extreme wasn't introduced until 10.4--and even then, it is turned off by default, and is only available for video cards that support it (i.e., newer video cards).  Arstechnica has a nice article on this.  From that perspective, the requirements of OS X and Vista are not much different (and to Vista's credit, it also supports DX9-capable integrated graphics sets--the Intel GMA 950, etc.--that rely on system memory).  However, Vista's graphics and composition technologies are more advanced than that of OS X--though we're not really seeing much of that power being put to use just yet.  DirectX 10 will also take it to the next level, with GPU scheduling and other things that will be unquestionable innovative in the market.

    With either system, though, the more VRAM you have, the better.  Consider that 1920x1200x32 is already 9 MB, and you can see how quickly the system soaks up VRAM (and then system RAM).  Most important perf-wise in the video subsystem for each OS is the amount of VRAM and the VRAM bandwidth and latency, then the system RAM and its bandwidth and latency.

    At any rate, from 10,000 feet, yes, it looks like Vista requires more to do what OS X is already doing.  But dig a little deeper, and you'll see that not only is Vista more advanced "under the hood," the requirements for both Vista and OS X (Quartz 2D Extreme enabled to compare the two more evenly) are more or less the same.

  • btw, forgot to add in my first post - awesome job on ReadyBoost, seriously, very nicely done - I would imagine this is gonna be perfect for laptop users :D

  • Bazanime, I believe there has been a bunch of improvements for RTM from RC2 so I would expect your flash drives may indeed work when Vista hits store shelves.

    I had a flash drive that did not work in RC2 that now works in RTM.

  • I would assume that Flash memory designed specifically for ReadyBoost will continue to work in the years to come with new versions of ReadyBoost via updates and/or the next version of Windows.

    Not sure why the Apple folks are coming here - Nick or Jim aren't comparing the two OS's in their posts. Instead, they are only discussing features in Vista.

  • someone
    156 Posts

    Now suppose you buy some Flash memory exclusively dedicated for ReadyBoost, how long does it last? Please tell me what happens to it after 2-3 years.

  • I wonder why Apple has such a huge market share? Run along fanboys.

  • RyanLM
    11 Posts

    What is even more fascinating about OSX when thinking about its low requirements is how much better it is at it than Vista.  I am hardly a Mac user or Fanboy, however I work in a shop that supports PC and Mac and I am the head MS tech.  You put a Vista box next to a Macbook for instance just and use the OSs, it really makes you ask what the heck took so long with Vista.

    Flip3d vs Expose : Expose usually just works, its quick and good at what it does.  Flip3d is almost the opposite.  The first time I use it, or say if I haven’t used it recently, the whole thing is just slow and jittery, and it seems half the windows are not being rendered either, just an app window with a program icon in the middle.  As far as being a good alternative to window management, both are good, but if I have over 10 windows open, flip sucks, I am rotating through windows forever.

    Transitions: I have read on shellrevealed the reasons as to why vista really can't do nice transitions - has to deal with drivers being in User Mode, flushing out the pipeline, etc.  Still, in the back of my mind it just screams bad design.  EVERYTHING in OSX has polish and feels smooth & quick, logging on, multi monitor switching, user switching, going from full screen to regular video, etc.  In Vista, it is harsh screen blanks, and even more funny, sometimes it fades out, then blinks!!!

    Flickering: NON Existent on OSX, comes standard with Vista.  Don’t believe me? Open up Media Player, Resize it.  Notice how the wonderful Glass area can’t keep up with the resize and it just turns black?  Why? Double Buffer anyone?  Every program seems to do this, feels so XP.  Somehow apple can do this with far less system requirements.

    Resolution independence: this was a feature I was looking forward too, but it doesn’t work too well.  The OS turns into a Picasso painting when you turn it up, just doesn’t scale right.  Apparently the next OSX will have this and for some reason I bet it will work.

    Control Panel: Nice if it was finished.  The new look of the control panel is very well done, easy to find things.  However, half of the items simply bring up the old Win98/2k/xp dialog, dumb.  Windows Appearance settings is done so well, Display properties is unchanged...  I am lost sometimes figuring out where time was spent.

    Boot Process: Win95?  

    Anyway, OSX will always be the better looking and more refined OS.  I have come to accept that, MS has one priority that will always win over that, it is compatibility which is the primary reason people use Windows.  Many of these issues have to do with making sure that Windows 3.1 font manager still works (I kid!) but seriously, at some point the baggage of old PCs, and old programs needs to be let go.  Personally, I would have favored thinning the herd with Vista and used a built in Virtual Machine (VPC?) to emulate a previous version of windows if needed.  Maybe for the next version of windows is 5 years...  It would be nice if not only Windows had amazing compatibility, but also was the best user experience as well, why not have two reasons to buy windows? :)

  • The simple idea behind ReadyBoost makes a monumental difference. I've been running Vista on a 900 MHz Celeron-based UMPC for several months; I did upgrade to 1 GB of RAM, but adding a 1 GB flash drive provides more "snappiness" overall. gives you some additional info on ReadyBoost as well as my experiences. Great job Vista team; simple but effective.

  • bazanime
    13 Posts

    Good question Inkmaster. It seems like the OSX carries off its fluid motions with much less resources.

    Any reason why that is?

    Also, vista rc2 doesn't seem to recognize my flash drives. Just my external hard drive is seen as mass storage and thats not ReadyBoost compatible.

    Will there be an update or will this issue be rectified in time for January 30th, or do i have to buy a new set of flash drives ReadyBoost certified?

  • Been using a 4GB ReadyBoost cache here on a 2GB RAM machine, makes enough difference on that to make me want to keep the stick in the back of my machine!

  • Hi, I wanted to ask this for... ever... - so I thought I'd ask the Vista Team...  Why is it that Mac OS X requires only a 16mb video card for all it's alpha-transparency GUI goodness, while Vista barely squizes by with 64?  Not trying to start a flame war or anything; just curious... I mean obviously theres that blur under the glass; but it cant be alone taking THAT much resources... can it?