When I try to configure ReadyBoost for a new flash SD Disk, I get the following error: "Unable to create cache. Access is denied".

Screenshot of the error

How can I solve it in order to enable ReadyBoost for that disk? I've already tried:

  • Running SFC /scannow
  • Format Disk (both NTFS and FAT32)
  • ChkDsk disk
  • Did you check if device haves a read only mode? – Francisco Tapia Apr 26 '15 at 15:47
  • I have created files on disk to check, and it's ok. It allowes the creation of new files in the partition. – KikoV Apr 26 '15 at 15:48
  • Is that device partitioned? – Francisco Tapia Apr 26 '15 at 15:49
  • Just one partition for the full size (FAT32). Indeed, I've tested with FAT32 and NTFS. – KikoV Apr 26 '15 at 15:50
  • 2
    Did you check whether the SD card meets the minimum speed requirements. Those are: •2.5 MB/sec throughout for 4 KB random reads •1.75 MB/sec throughout for 512 KB random writes. You can use Atto to check that. ==> attotech.com/disk-benchmark – whs Apr 26 '15 at 17:41

Windows needs exFAT-formatted SD cards to use more than 4 GB for ReadyBoost. Though you can reformat the card as exFAT, two caveats:

  1. ReadyBoost accesses the card heavily, sometimes causing early failure.

  2. My personal experience with ReadyBoost on two PC's has been that there was no perceptible change in speed; your mileage may vary, though.

  • 1
    DrMoishe: My experience is similar. ReadyBoost helps if you are doing a lot of file accesses that the SuperFetch cache helps with (SuperFetch is the only thing that uses ReadyBoost's storage), AND your RAM size is "marginal" for your workload. If you already have plenty of RAM, there's nothing for RB to help with; conversely if you are really scarce on RAM, you're paging a lot of "live" stuff and RB can't help with that. – Jamie Hanrahan Apr 26 '15 at 20:44
  • I've tried with exFAT. Still Access denied error. – KikoV Apr 27 '15 at 21:08

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