Readyboost

Introduction
RAM upgrades are probably one of the easiest upgrades to do to a modern PC. Pop the case of, stick in some new RAM, put the case back on and off you go. However, some people simply don’t like the idea of opening up a PC. For others, a RAM upgrade would require taking out old RAM, increasing the cost of the upgrade, while a few people might even have maxed out their system’s RAM limit.

In Windows Vista Microsoft has implemented a new system that can use flash-based storage devices as additional memory, speeding up the response times of the Operating System and its applications. The best bit is, no screwdriver is required… it can all be done with USB 2.0 devices.

The technology
At the time of writing, Vista isn’t quite available to the public, but it has been released to manufacturers, and a vast number of testers have already had a play with it. As such, just about everything that needs to be known about ReadyBoost is available.

Before we get into ReadyBoost proper, let’s have a quick lesson in paging. Running programs need memory and that memory is limited. However, it’s possible to consume more than the physically available amount of memory with the help of the Windows page file. This is a file on disk into which portions of data from memory can be moved.

Applications that are sitting idle might get some of their data paged to disk to make space for other applications, or simply to ensure that any applications that might start soon, will be able to load up fairly quickly. If you’re running a lot of applications, swapping between them might appear slow, as data has to be read from the page file. If you’re unlucky enough to be using more memory than you have, the page file will be used a lot, slowing the system down significantly.

The problem lies in the fact that hard drives are a number of orders of magnitude slower at data transfer than RAM. They’re great for permanent storage, but terrible for quick access, particularly random access. Hard drives have moving parts, so navigating to random parts of the disk takes time. It’s this access latency, more than their lower data rate that makes them a hinderence.

Enter ReadyBoost. Insert a flash-based device into your Vista-based PC, and the auto-run prompt will ask if you want to use ReadyBoost on it. The flash device could be a thumb drive, an SD card or any other sort of memory card. Flash memory isn’t much quicker at transferring data compared to the noble hard disk, in fact it’s often slower. However, it can often serve random access requests quicker; exactly the sort of thing that’s useful for paging.

Vista will use the free space on a compatible flash device as a cache for certain paged data. The data that enters that cache will be stuff that’s likely to be lots of small, randomly accessed segments. Data that’s sequential is better off on hard disk, if it really needs to be paged. ReadyBoost is only cache, so a copy of the data is still kept in the page file as well, but Vista will look to the speedier cache for what it needs first, before heading over to the hard disk. As such, a ReadyBoost enabled drive can be removed at will, without any loss of data within running applications.

Not all flash devices are ReadyBoost compatible. The target device needs to be reasonably quick at small sized random access read and write requests. It doesn’t matter how quickly it can transfer one large file; it might still be slow for random access operations, in which case there’d be little point in using it to speed up the system. Vista will make sure a device is worth using for ReadyBoost before doing so.

A minimum of 64MiB free space is needed on the ReadyBoost drive, so if all you have is a full-up thumb drive, you won’t be able to use ReadyBoost.

The players
Microsoft is, of course, the key player in the implementation of this technology, but ReadyBoost relies on flash device manufacturers producing products that will actually help speed up systems. There are lists (e.g. http://www.grantgibson.co.uk/misc/readyboost/) of compatible devices from numerous manufacturers.

Some manufacturers also appear to be marketing flash drives directly at ReadyBoost usage. Corsair is the first example of this, with a new flash drive designed specifically to meet the criteria set out by Microsoft (http://www.hexus.net/content/item.php?item=7529).

Closing thoughts
While ReadyBoost is an easy, and usually relatively cheap way of giving a sluggish system a bit of a boost, it’s still best to upgrade RAM whenever possible. RAM is very quick in comparison to both hard disks and flash drives. However, the quicker random access times of flash drives do make them a better workhorse than a hard drive, when paging is required.