Ready Boost - Requirements

Requirements

For a device to be compatible and useful, it must conform to these requirements:

  • The removable media's capacity must be at least 256 MB (250 MB after formatting, Windows 7 reports in its Event Log a required minimum of 235 MB).
  • Windows 7 allows up to eight devices for a maximum of 256 GB of additional memory, with up to 32 GB on a single storage device.
  • The device must have an access time of 1 ms or less.
  • The device must be capable of 2.5 MB/s read speeds for 4 KB random reads spread uniformly across the entire device, and 1.75 MB/s write speeds for 512 KB random writes spread uniformly across the device.

Other considerations:

  • Vista's ReadyBoost supports NTFS, FAT16 and FAT32 from SP1. Windows 7 also supports the new exFAT file system. As the ReadyBoost cache is stored as a file, the flash drive must be formatted as NTFS or exFAT to allow a cache larger than the FAT32 filesize limit of 4 GB (or FAT 16's 2 GB).
  • The initial release of ReadyBoost for Windows Vista supported one device. Windows 7 supports multiple flash drives for ReadyBoost, so performance improvement similar to RAID 0 can be expected.
  • The ReadyBoost algorithm was improved in Windows 7, resulting in better performance. One experiment showed reading of flash memory up to 5-10 times faster than Windows Vista due to higher hit rate.
  • Because ReadyBoost stores its cache as a file on the root directory of the drive, rather than using the flash memory without a file system, the file system must be mounted and assigned a drive letter. The ReadyBoost cache is created on the root directory of the drive.
  • If the system drive (the primary drive, with Windows system files on it) is a solid-state drive (SSD), ReadyBoost is disabled, as reading from that drive would be at least as fast as reading from the ReadyBoost drive.

Depending on the brand, wear and tear from read-write cycles, and size of the flash memory, the ability to format as NTFS may not be available. Enabling write caching on the flash drive by selecting Optimize for performance in Device Manager allows formatting as NTFS.

ReadyBoost is not available on Windows Server 2008.

According to Jim Allchin, for future releases of Windows, ReadyBoost will be able to use spare RAM on other networked Windows PCs.

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