LEARN ABOUT READYBOOST
ReadyBoost Information Directly from Microsoft
ReadyBoost supports the use of nonvolatile flash storage devices to boost system performance. Devices enhanced for ReadyBoost provide dedicated space outside main memory where SuperFetch can store a cache of performance-crucial data for fast random access. Although not as fast as main memory, nonvolatile flash memory significantly outperforms conventional disk media in random reads by avoiding the rotational and seek latencies. All data written to the cache is compressed at a 2:1 ratio and encrypted by using AES-128 to ensure security of the data.
When flash storage devices enhanced for ReadyBoost are installed in PCs, Windows Vista AutoPlay shows a dialog box to the users asking them whether they would like to use the devices with ReadyBoost to improve performance. Although multiple flash storage devices can be supported as logical drives, Windows Vista supports a maximum of one of these logical drives as a ReadyBoost device.
The subsequent property sheet for the device provides options for users to select an appropriate cache size to put on the device.
Cache sizes can range from 230 MB up to 4 GB. Microsoft recommends at least a 1:1 ratio of ReadyBoost cache size to main memory (RAM) capacity. Higher ratios up to 3:1 will realize optimal performance benefits.
Every page of data in the ReadyBoost cache is a copy of a page on disk. If the device is removed from the computer, no data is lost, but the computer loses the performance boost and the operating system reverts to sending requests to the disk.
Key Benefits
Devices enhanced for ReadyBoost accelerate the launching of frequently used programs and opening of frequently accessed files and settings.
Integrated (built-in) devices enhanced for ReadyBoost, which will not be removed routinely, can be configured to improve performance during the time immediately after a resume-from-hibernate. Integrated devices enhanced for ReadyBoost retain data through power state transitions and can therefore provide faster access to data that would otherwise require disk I/O.
| User experience | Description of performance improvement |
|---|---|
| Heavy usage of multiple programs at once | The flash storage device enhanced for ReadyBoost provides a dedicated space for SuperFetch data, which can be accessed at times when the main memory hasn’t been populated with SuperFetch data yet, or when SuperFetch data has recently been forced out of main memory by another request. |
| Poor program launch performance while using other programs | During disk contention when many programs are trying to access the disk contents, Windows Vista can still access frequently used programs and files in the flash storage device, resulting in more responsive user experiences. |
Using a simulated workload on a PC running Windows Vista with 512 MB of main memory, storage devices of various capacities enhanced for ReadyBoost significantly improve performance as shown in this table.
| ReadyBoost capacity | Time to complete workload (seconds) | Percent improvment |
|---|---|---|
| 0 MB | 42.45 | -- |
| 512 MB | 27.12 | 36.12 |
| 1,024 MB | 25.21 | 40.61 |
| 2,048 MB | 24.72 | 41.78 |
Note: Running Windows Vista with 512 MB of main memory and a multi-application simulated workload places the system under main memory pressure. Under these conditions, ReadyBoost can provide considerable benefit. The benefit provided is configuration dependent, so the percent improvement is variable.
Cenatek notes on ReadyBoost
Microsoft has placed performance requirements on flash drives for use with ReadyBoost. Since the ReadyBoost feature relies on the random access performance of the flash drive, it is important that the flash drive has high performance metrics in that area.
However, Microsoft lowered the flash performance bar on the final release of Vista. This has allowed some drives that are not high performance to be used as ReadyBoost devices. This can result in a negligible performance boost and, in some cases, can even slow the machine down. That is why it is important to compare performance specifications when buying a flash drive for use with ReadyBoost.
The ReadyBoost system is designed around 4KB random reads. Most flash disks are not optimized for random reads. The Rocket Drive Micro is.
Flash devices, like all consumer electronic products, can be built with varying levels of quality and performance. The Rocket Drive line is engineered from the ground up, starting with the controller, to be the highest performing, most reliable product we can make. We use only the very top performing flash available and hand route all our boards.
Links :
Wiki Page on ReadyBoost
http://en.wikipedia.org/wiki/ReadyBoost
Channel 9 Video
http://channel9.msdn.com/showpost.aspx?postid=242429