Articles: Memory

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This time we will test flash drives in a different way. First, we’ve collected devices with a storage capacity of at least 4GB. Second, the testing will take two steps and include more tests. The reason for such changes is the release of Microsoft’s new operating system Windows Vista. It may seem there is no connection between the release of the new OS and flash drives, yet it exists really.

Microsoft Windows Vista offers new user-oriented features that utilize those technological advances that have been made since the release of the earlier version of the OS, Windows XP. One innovation concerns flash drives. It is called Windows Vista ReadyBoost technology. What does this technology do? As you know, the more memory the computer has, the better and faster it works. System memory can be accessed at a much higher speed than the virtual memory on the hard disk. Unfortunately, memory modules are rather expensive. And even if you’ve got enough money, you cannot install more modules than there are memory slots on your mainboard.

Windows Vista provides an opportunity to avoid such limitations by using Windows ReadyBoost technology. Its point is in allowing the OS to use additional memory on a USB flash drive (this technology can also work with SD and CF cards). This flash memory serves as an additional cache with an access time lower than that of the hard disk. Of course, the flash drive must be quick enough for that. On connecting it, Windows Vista benchmarks its speed by running a quick performance test to make sure the drive complies with the ReadyBoost requirements. If it does, the user will be offered the option to use the flash drive to increase system performance. A part of the drive’s storage space must then be reserved for ReadyBoost. Windows will recommend you how much should be reserved.

We’ll check out the efficiency of our flash drives in Windows Vista in the second part of this article. The first part will contain some preparation work.

As mentioned above, a flash drive must meet certain requirements for Vista’s ReadyBoost feature to be efficient. The drive must support USB 2.0 and meet some minimum speed requirements. It must have a speed of 2.5MB/s or higher and 1.75MB/s or higher when reading and writing, respectively, random 4KB data blocks. Besides that, the minimum amount of memory on a flash drive utilized as a system cache by means of ReadyBoost technology is 230MB; the maximum amount is 4GB.

It means that flash drives with capacities lower than 256MB are not compatible with ReadyBoost. Microsoft recommends a minimum ratio of the ReadyBoost cache to the amount of system memory as 1:1. It can be increased to 3:1 for higher efficiency. All data written into the ReadyBoost cache are compressed with a 2:1 coefficient and encrypted with the AES-128 algorithm to ensure their confidentiality. Each data page stored in the ReadyBoost cache is a copy of the page stored on the hard disk, so information cannot be lost if the flash drive is unplugged from the USB port. System performance just goes down to the ordinary level in that case.

Besides the minimum requirements, there are recommended parameters, too. An “enhanced-for-ReadyBoost” device is a flash drive that has a capacity of 512MB or higher, a minimum random read speeds of 5MB/s for 4KB data blocks, and a minimum write speed of 3MB/s for 512-byte data blocks.

The first part of this article contains test results we’ve obtained from the drives with our traditional test methods. The second part will cover their efficiency in Windows Vista.

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