ReadyBoost

ReadyBoost is an operating system feature included with Microsoft's Windows Vista operating system. It works by using flash memory, USB 2.0 drive, SD card, CompactFlash or any kind of portable massive flash storage as a drive for disk cache.

ReadyBoost is also used to facilitate SuperFetch, an updated version of Windows XP's prefetcher which performs analysis of boot-time disk usage patterns and creates a cache which is used in subsequent system boots.

Overview

Using ReadyBoost-capable flash memory (NAND memory devices) for caching allows Windows Vista to service random disk reads with performance that is typically 80-100 times faster than random reads from traditional hard drives. This caching is applied to all disk content, not just the page file or system DLLs. Flash devices are typically slower than the hard drive for sequential I/O, so to maximize performance, ReadyBoost includes logic to recognize large, sequential read requests and then allows these requests to be serviced by the hard drive. cite web|url=http://blogs.msdn.com/tomarcher/archive/2006/06/02/615199.aspx |title=ReadyBoost Q&A |accessdate=2008-01-11 |last=Archer |first=Tom |coauthors=Ayers, Matt |date=2006-06-02 |work=Tom Archer's Blog |publisher=MSDN Blogs ]

When a compatible device is plugged in, the Windows AutoPlay dialog offers an additional option to use the flash drive to speed up the system; an additional "ReadyBoost" tab is added to the drive's properties dialog where the amount of space to be used can be configured.cite web
url=http://blogs.msdn.com/tomarcher/archive/2006/04/14/576548.aspx
title=ReadyBoost - Using Your USB Key to Speed Up Windows Vista
date=April 14 2006
accessdate=2006-05-21
author=Tom Archer
work=Tom Archer's Blog
publisher=Microsoft] 250 MB to 4 GB of flash memory can be assigned. ReadyBoost encrypts, with AES-128, and compresses all data that is placed on the flash device; Microsoft has stated that a 2:1 compression ratio is typical, so that a 4 GB cache could contain upwards of 8 GB of data.cite web
url=http://www.microsoft.com/technet/technetmag/issues/2007/03/VistaKernel/default.aspx
title=Inside the Windows Vista Kernel: Part 2
month=March | year=2007
accessdate=2007-03-01
author=Mark Russinovich
authorlink=Mark Russinovich
work=TechNet Magazine
publisher=Microsoft]

According to Jim Allchin, for future releases of Windows, ReadyBoost will be able to use spare RAM on other networked Windows Vista PCs.cite web
url=http://hive.net/Member/blogs/the_insider/archive/2006/05/23/15378.aspx
title=Jim Allchin
date=23 May 2006
accessdate=2006-11-01]

For a device to be compatible and useful it must conform to the following requirements:
* The capacity of the removable media must be at least 256 MB (250 after formatting)
* Devices larger than 4 GB will have only 4 GB used for ReadyBoost
* The device should 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
* The device must have at least 235 MB of free space
* NTFS, FAT16 and FAT32 are supported
* The initial release of ReadyBoost supports one device
* The recommended amount of flash memory to use for Windows ReadyBoost acceleration is one to three times the amount of random access memory (RAM) installed in your computer

Depending on the brand, wear and tear due to 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 will allow formatting as NTFS. [ [http://blogs.msdn.com/oldnewthing/archive/2004/04/05/108205.aspx How can I format my USB drive as NTFS?: The Old New Thing] ]

Performance

A system with 512 MB of RAM (the minimum for Windows Vista) can see significant gains from ReadyBoost. [ [http://www.anandtech.com/systems/showdoc.aspx?i=2917&p=5 AnandTech: Windows Vista Performance Guide ] ] In one test case, ReadyBoost sped up an operation from 11.7 seconds to 2 seconds (increasing physical memory from 512 MB to 1 GB reduced it to 0.8 seconds). [ [http://www.anandtech.com/systems/showdoc.aspx?i=2917&p=6 AnandTech: Windows Vista Performance Guide ] ]

The core idea of ReadyBoost is that a flash drive has a much faster seek time (less than 1 millisecond), allowing it to satisfy the requests fairly quickly compared to a hard drive when booting or reading certain system files. It also leverages the inherent advantage of having two parallel sources from which to read data. Unfortunately USB flash drives are slow in terms of reads and writes, compared to modern desktop hard drives. Desktop hard drives can sustain anywhere from 2 to 10 times the transfer speed of USB flash drives. The USB flash drives hold an advantage in random access times which are typically around 1ms, compared to the 12ms and upwards of desktop hard drives.

On laptop computers the performance shifts more in the favor of flash memory, laptop memory being priced relatively higher than that for desktop systems, and with many laptops using relatively slow 4200 rpm and 5400 rpm hard drives. Additionally, on a laptop, the ReadyBoost caching can reduce hard drive access, allowing the hard drive to spin down for increased battery life. [ [http://www.anandtech.com/showdoc.aspx?i=3009&p=8 AnandTech: Investigating Intel's Turbo Memory: Does it really work? ] ] Also, because of the nature of the power management typically enabled during mobile use of a laptop it is a more power efficient way of increasing equipment productivity.

The performance of NAND flash caching (in the form of Intel's Turbo Memory technology) has also been called into question by some computer manufacturers. [ [http://news.com.com/HP+says+no+to+Intels+Turbo+Memory/2100-1004_3-6188531.html HP says no to Intel's Turbo Memory - CNET News.com ] ] According to an online review [ [http://www.anandtech.com/mobile/showdoc.aspx?i=3009&p=2 Investigating Intel's Turbo Memory: Does it really work?] ] TurboMemory results in negligible performance or battery life gain, despite the fact that TurboMemory adds an average of $100 to the price of a laptop.

Prior to Vista Service Pack One (SP1), ReadyBoost was quite ineffective when the computer/laptop was put to sleep. ReadyBoost failed to recognize the data in the cache and restarted the caching process when returned from sleep mode. Vista SP1 addresses this problem. [ [http://www.istartedsomething.com/20070709/vista-sp1-readyboost-bug/ Vista SP1 will fix critical ReadyBoost performance bug ] ]

Note

As flash drives do not have an infinite number of writes that can be carried out, ReadyBoost will eventually wear out the drive it uses — although this may take a long time, depending on various factors. According to Microsoft, the drive should be able to operate for at least ten years.

See also

* Features new to Windows Vista
* Superfetch

References

External links

Microsoft links

* [http://www.microsoft.com/windows/products/windowsvista/features/details/readyboost.mspx Windows Vista: Features Explained: Windows ReadyBoost]
* [http://windowshelp.microsoft.com/Windows/en-US/Help/12428141-2e4c-43ab-8dd2-a6ed6e3b87761033.mspx Windows Vista Help Page on ReadyBoost]
* [http://www.microsoft.com/windows/products/windowsvista/features/details/performance.mspx Windows Vista: Features Explained: Performance Features (of which ReadyBoost is one)]
* [http://channel9.msdn.com/showpost.aspx?postid=242429 Channel9 interview with Michael Fortin on ReadyBoost and other performance technologies in Windows Vista]
* [http://www.microsoft.com/whdc/winlogo/HWrequirements.mspx Section STORAGE-009 in Windows Logo Program Requirements Suite, Version 3.09]

Other links

* Microsoft's Software Patent on ReadyBoost [http://www.google.com/search?q=20060090031 via google]
* [http://www.anandtech.com/systems/showdoc.aspx?i=2917&p=5 AnandTech: Windows Vista Performance Guide - ReadyBoost, ReadyBoost Performance Analysis, and Hard Drive Performance and ReadyBoost]
* [http://www.winvistatips.com/what-is-readyboost-a25.php How to use and configure Readyboost]
* [http://www.tomshardware.com/2007/01/31/windows-vista-superfetch-and-readyboostanalyzed/ In depth Tom's Hardware article with analyses of ReadyBoost and Superfetch]
* [http://www.grantgibson.co.uk/misc/readyboost/ Lists of compatible ReadyBoost hardware]
* [http://www.readyboostmemory.com/how-to-use-readyboost.html How to use ReadyBoost guide with pictures]
* [http://cybernetnews.com/2007/04/26/cybernotes-use-any-usb-drive-or-memory-card-with-readyboost-on-vista Use any USB drive or memory card with ReadyBoost on Vista]
* [http://area-71.net/rbmon/ ReadyBoost Monitor]