Readyboost deletes cache on reboot

Discussion in 'Windows Vista Performance' started by Bob, Mar 22, 2007.

  1. Bob

    Bob Guest

    Just poking around under Vista's hood and it seems that Ready Boost deletes
    it's cache and reforms it when a computer is rebooted. This appears to be
    normal operation for Ready Boost..I had thought that once it sets up it's
    cache that it would remain rather than rebuilding it on each boot as it
    takes time to build it each time.
    Bob, Mar 22, 2007
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  2. Mine does this as well, why is this?

    My computer is unusable for 5 minutes after start-up whilst it updates the
    readyboost drive

    Andy Pritchard, Mar 22, 2007
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  3. Really? I don't think mine is doing that. Tell me how you know it is
    reformatting and reloading, and I'll check mine.


    Steve Thackery, Mar 22, 2007
  4. Bob

    Bob Guest

    Go here:
    Control Panel
    System Maintenance
    Performance Information and Tools
    in the left pane, Advanced tools
    View performance issues in event log
    Microsoft/ReadyBoost /Operational

    Click on the "Information" categories on the top left side and in the bottom
    "General" tab it will say what operation was completed.
    You will see an entry for the time at which you shutdown/rebooted that says
    " A ReadyBoost cache was successfully deleted on the device (USB FLASH

    At your boot up time you will see an entry that reads:
    "A ReadyBoost cache was successfully created on device (USB FLASH DRIVE) of
    1960MB ( I'm using a 2GB flash drive so this size will vary depending on the
    size of your flash drive)

    Another thing I notice is this message:
    "A defrag has completed. A boot plan will be calculated soon. Defrag
    timestamp (UTC) :3/21/2007 5:36:03 PM "

    So it appears to mean that the ReadyBoost cache is being defragged on it's
    own ?
    I have my computer set to defrag the hard drives once a month on the 1st so
    I know this defrag is not controlled by my settings. Must be built in to
    the ReadyBoost program?

    Bob, Mar 22, 2007
  5. If the cache remained it would be a security hazard for corporations and



    Richard Urban MVP
    Microsoft Windows Shell/User
    Richard Urban, Mar 22, 2007
  6. Bob

    Bob Guest

    Makes sense...I thought that the data was encrypted to prevent that from
    Good info to know.
    Bob, Mar 22, 2007
  7. Bob

    Steven Wimer Guest

    I'm suprised an MVP would say that when Tom Archer's Blog says this:

    Q. Isn't user data on a removable device a security risk?

    A: Everything that is written to the flash device is secured by ReadyBoost's
    128-bit encryption, which means you don't have to worry about data security.

    And Technet says:

    The driver encrypts each block it writes using Advanced Encryption Standard
    (AES) encryption with a randomly generated per-boot session key in order to
    guarantee the privacy of the data in the cache if the device is removed from
    the system.
    Steven Wimer, Mar 22, 2007
  8. Hey! We don't have the time to read everything. The fact remains that the
    cache IS deleted when you shutdown/reboot. If you shutdown and boot up into
    Windows XP the cache is no longer there. All the drives space is available
    for Windows XP to use.

    It either adds to the encryption, or is a "real" bug - not one of the
    imaginary ones that the trolls write about.



    Richard Urban MVP
    Microsoft Windows Shell/User
    Richard Urban, Mar 22, 2007
  9. I have had a look through the registry for any obvious settings like
    doNotDeleteCache=0 but to no avail. As an MVP are you able to contact an
    internal support team about the issue?

    Andy Pritchard, Mar 22, 2007
  10. Bob,

    Mine is definitely not doing it. I've rebooted a couple of times, and all
    it shows is 'Caching was enabled for device...', followed by another entry
    entitled 'Summary of ReadyBoost performance'.

    Steve Thackery, Mar 22, 2007
  11. The fact remains that the cache IS deleted when you shutdown/reboot.

    Only sometimes. See my post in reply to Bob above. Mine is definitely not
    deleting the cache on shutdown/reboot.

    This is obviously a bug affecting only some people.

    Steve Thackery, Mar 22, 2007
  12. Andy Pritchard, Mar 22, 2007
  13. Bob

    Bob Guest

    The first thing that tipped me off was seeing the date and time on .sfcache
    file that gets created on the USB drive, after a reboot. I had previously
    looked at the file date and it was dated from 2 days before ( last time I
    had rebooted the machine). After a reboot I checked the file date and it was
    the time of the reboot, so I dug a little deeper into Vista's tools and
    found the delete and recreate entries. I also notice that on boot up the
    flash drive's led flashes for 3 or 4 minutes, as I now know the new cache is
    being created ( and populated?). I'll be watching to see if it's a bug to be
    fixed or maybe some setting that needs to be changed somewhere.
    Bob, Mar 22, 2007
  14. Bob

    Victek Guest

    That may be, but if ReadyBoost actually degrades performance instead of
    improving it what's the point?
    Victek, Mar 23, 2007
  15. As stated above, the degradation only occurs on some people's machines, and
    looks very much like a bug.

    Steve Thackery, Mar 24, 2007
  16. On Sat, 24 Mar 2007 01:42:50 -0000, "Steve Thackery"
    The Vista team were aware that the benefits of ReadyBoost would be a
    trade-off that depends on whether the USB flash drive is fast and
    large enough to make it worthwhile.

    That's why Vista will test such drives, and refuse to enable
    Readiboost of the drive is "too slow".

    So the next thing we see, are hacks to force Vista to do Readiboost on
    slow USB flash drives.

    If, OTOH, you're using a drive that Vista doesn'thave to be hacked to
    use, and it's still slower than without it, then there's either a bug,
    or Vista's estimation of the break-even point was off, or there's
    something particular to your system and the way you use it that is at
    odds with the assumptions made by the Vista team in their assessment.

    It will certainly delete the cache on reboot, else could be open to
    exploits that pre-seed the contents between sessions.

    Tip Of The Day:
    To disable the 'Tip of the Day' feature...
    cquirke (MVP Windows shell/user), Mar 24, 2007
  17. Bob

    Guest Guest

    The service crashed perhaps.
    Guest, Mar 24, 2007
  18. Bob

    Victek Guest

    That all makes sense, but how do we explain the instances where the
    readyboost cache is NOT deleted between reboots? I'm observing that it IS
    deleted on my system, but some people say it's persistent.
    Victek, Mar 24, 2007
  19. It's not crashing because on shutdown in the event log it says:

    "A ReadyBoost cache was successfully deleted on the device (Kingston
    DataTraveler R)."

    Andy Pritchard, Mar 24, 2007
  20. Bob

    Bob Guest

    So... do we know if it's supposed to be deleted on shutdown or not ? What do
    the people who developed the program say..?
    Bob, Mar 24, 2007
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