Windows 7 / Getting Started

Windows ReadyBoost

Windows 7 supports Windows ReadyBoost, originally introduced with Windows Vista. Ready- Boost uses external USB flash drives as a hard disk cache, thus improving disk read performance in some circumstances. Supported external storage types include USB thumb drives as shown in Figure below, SD cards, and CF cards.

ReadyBoost uses flash storage to improve disk read performance

Unlike Windows Vista, Windows 7 recognizes that ReadyBoost will not provide a performance gain when the primary disk is an SSD. Windows 7 disables ReadyBoost when reading from an SSD drive.

External storage must meet the following requirements:

  • Capacity of at least 256 MB, with at least 64 kilobytes (KB) of free space. The 4-GB limit of Windows Vista has been removed.
  • At least a 2.5 MB/sec throughput for 4-KB random reads
  • At least a 1.75 MB/sec throughput for 1-MB random writes

Unfortunately, most flash storage provides only raw throughput performance statistics measured under ideal conditions, not the very specific 4-KB random reads required by ReadyBoost. Therefore, the most effective way to determine whether a specific flash drive meets ReadyBoost requirements is simply to test it. Windows Vista and Windows 7 automatically test removable storage when attached. If a storage device fails the test, Windows will automatically retest the storage on a regular basis.

Some devices will show the phrase "Enhanced for Windows ReadyBoost" on the packaging, which means that Microsoft has tested the device specifically for this feature. If you connect a flash drive that meets these requirements, AutoPlay will provide ReadyBoost as an option.

AutoPlay will prompt the user to use a compatible device with ReadyBoost.

Alternatively, you can configure ReadyBoost by right-clicking the device in Windows Explorer, clicking Properties, and then clicking the ReadyBoost tab. The only configuration option is to configure the space reserved for the cache. You must reserve at least 256 MB. Larger caches can improve performance, but the ReadyBoost cache cannot be greater than 4 GB on a FAT32 file system or greater than 32 GB on an NTFS file system.

Windows Vista and Windows 7 use the Windows SuperFetch algorithm (the successor to Windows Prefetcher) to determine which files should be stored in the cache. SuperFetch monitors files that users access (including system files, application files, and documents) and preloads those files into the ReadyBoost cache. All files in the cache are encrypted using 128-bit AES if the flash storage device is removable, but hardware manufacturers can choose to disable encryption on internal, nonremovable ReadyBoost devices. Because the ReadyBoost cache stores a copy of the files, the flash drive can be removed at any point without affecting the computer-Windows will simply read the original files from the disk.

ReadyBoost provides the most significant performance improvement under the following circumstances:

  • The computer has a slow hard disk drive. Computers with a primary hard disk Windows Experience Index (WEI) subscore lower than 4.0 will see the most significant improvements.
  • The flash storage provides fast, random, nonsequential reads. Sequential read speed is less important.
  • The flash storage is connected by a fast bus. Typically, USB memory card readers are not sufficiently fast. However, connecting flash memory to an internal memory card reader might provide sufficient performance.

Computers with fast hard disks (such as 7,200- or 10,000-RPM disks) might realize minimal performance gains because of the already high disk I/O. ReadyBoost will read files from the cache only when doing so will improve performance. Hard disks outperform flash drives during sequential reads, but flash drives are faster during nonsequential reads (because of the latency caused when the drive head must move to a different disk sector). Therefore, ReadyBoost reads from the cache only for nonsequential reads.

Note In the author's informal experiments, enabling ReadyBoost on a 1-GB flash drive on a laptop computer with a WEI disk rating of 3.7 decreased Windows startup times by more than 30 percent. Gains on computers with a WEI disk rating of more than 5 were minimal.

ReadyBoost creates a disk cache file named ReadyBoost.sfcache in the root of the flash drive. The file is immediately created for the full size of the specified cache; however, Windows will gradually fill the space with cached content.

To monitor ReadyBoost performance, use the System Tools\Performance\Monitoring Tools \Performance Monitor tool in the Computer Management console and add the ReadyBoost Cache counters. These counters enable you to monitor how much of the cache is currently being used and when the cache is read from or written to. It does not tell you exactly what performance benefit you are achieving by using ReadyBoost, however.

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In this tutorial:

  1. Managing Disks and File Systems
  2. Overview of Partitioning Disks
  3. How to Choose Between MBR or GPT
  4. Converting from MBR to GPT Disks
  5. GPT Partitions
  6. Choosing Basic or Dynamic Disks
  7. Working with Volumes
  8. How to Create a Simple Volume
  9. How to Create a Spanned Volume
  10. How to Create a Striped Volume
  11. How to Resize a Volume
  12. How to Delete a Volume
  13. How to Create and Use a Virtual Hard Disk
  14. File System Fragmentation
  15. Backup And Restore
  16. How File Backups Work
  17. File and Folder Backup Structure
  18. How System Image Backups Work
  19. How to Start a System Image Backup from the Command Line
  20. How to Restore a System Image Backup
  21. System Image Backup Structure
  22. Best Practices for Computer Backups
  23. How to Manage Backup Using Group Policy Settings
  24. Previous Versions and Shadow Copies
  25. How to Manage Shadow Copies
  26. How to Restore a File with Previous Versions
  27. How to Configure Previous Versions with Group Policy Settings
  28. Windows ReadyBoost
  29. BitLocker Drive Encryption
  30. How BitLocker Encrypts Data
  31. How BitLocker Protects Data
  32. TPM with External Key (Require Startup USB Key At Every Startup)
  33. TPM with PIN (Require PIN At Every Startup)
  34. TPM with PIN and External Key
  35. BitLocker To Go
  36. BitLocker Phases
  37. Requirements for Protecting the System Volume with BitLocker
  38. How to Enable the Use of BitLocker on the System Volume on Computers Without TPM
  39. How to Enable BitLocker Encryption on System Volumes
  40. How to Enable BitLocker Encryption on Data Volumes
  41. How to Manage BitLocker Keys on a Local Computer
  42. How to Manage BitLocker from the Command Line
  43. How to Recover Data Protected by BitLocker
  44. How to Disable or Remove BitLocker Drive Encryption
  45. How to Decommission a BitLocker Drive Permanently
  46. How to Prepare AD DS for BitLocker
  47. How to Configure a Data Recovery Agent
  48. How to Manage BitLocker with Group Policy
  49. The Costs of BitLocker
  50. Windows 7 Encrypting File System
  51. How to Export Personal Certificates
  52. How to Import Personal Certificates
  53. How to Grant Users Access to an Encrypted File
  54. Symbolic Links
  55. How to Create Symbolic Links
  56. How to Create Relative or Absolute Symbolic Links
  57. How to Create Symbolic Links to Shared Folders
  58. How to Use Hard Links
  59. Disk Quotas
  60. How to Configure Disk Quotas on a Single Computer
  61. How to Configure Disk Quotas from a Command Prompt
  62. How to Configure Disk Quotas by Using Group Policy Settings
  63. Disk Tools
  64. EFSDump
  65. SDelete
  66. Streams
  67. Sync
  68. MoveFile and PendMoves