If you're reading this to see how fast today's
USB flash memory keys transfer
data, then you should look elsewhere. This
isn't about moving large amounts of digital
imagery or audio around. This is strictly about
What is ReadyBoost?
ReadyBoost is a technology built into Windows
Vista that caches disk reads onto a flash memory
device. It can work with USB memory keys, flash
memory cards, such as SD and CompactFlash, and
other types of flash devices. It caches all
types of file reads, not just the working set,
nor just DLL's or other persistent
operating system data.
ReadyBoost does not cache file
writes—it's a write-through cache. That way, you
never lose any precious data that's meant to be
written to a hard drive. After all, a flash
memory key can get yanked out of a system at any
time. The cache itself is encrypted using
AES-128 encryption, so no one can steal your
flash memory key and casually browse through the
cache file to see what you've been doing. Continued... Microsoft's Tom Archer presented a small
FAQ written by Matt Ayers on
Archer's blog. What follows is a summary of
a few of Matt's comments.
Some people note that reading from
flash memory is actually slower than reading
from a fast hard drive. As it turns out, this is
true mostly for large, sequential file reads.
The drive is assisted by 2MB-16MB of onboard
data buffer, which is in itself much faster than
flash memory. However, ReadyBoost is smart
enough to just let the system read large,
sequential blocks of data directly from the hard
Where ReadyBoost comes in is with
small blocks of random I/O, like paging files,
or pulling other random, small amounts of data.
Need a DLL or OCX file for a particular app?
ReadyBoost can serve it up faster than the disk
can locate it. Basically, if the drive head has
to move a substantial amount to find small
chunks of data, ReadyBoost can improve
performance. If a drive is streaming a video or
loading a large
game level, then ReadyBoost gets out of the
The catch when it comes to hardware
performance is this caching and serving up of
small, random bits of data. As it turns out,
many flash memory devices aren't particularly
good at this. They are often optimized for
moving large chunks of data, but not necessarily
good at lots of random accesses of bits of data
and applications. Much of this has to do with
the tiny controller embedded in every USB memory
device. Some are good at small, random access
reads and others are not. Another issue is the
way flash memory is laid out. Some larger
capacity devices that can be had fairly cheaply
get their high transfer rates by using a small
amount of very fast flash memory, with the bulk
being slower memory. In effect, the fast flash
is acting as a buffer for the slower flash.
The minimum requirements for a USB
memory device to be ReadyBoost capable is
2.5MB/sec for 4K random access reads and
1.5MB/sec for 512K random writes—and that rate
has to be achieved across the whole flash memory
space. When you plug a USB memory device into
the system, Vista actually does a performance
check to see if the device meets the standard.
Vista won't allow you to use a device it thinks
will slow the system down. Note that USB hard
drives won't work.
Microsoft's general recommendation for
maximum benefit from ReadyBoost is to match the
capacity of the flash device to the size of your
system's main memory. So if you have 2GB of
system RAM, use a 2GB USB key. Note that some
benefit is gained from using any flash device,
and the capacities supported for ReadyBoost
range from 256MB to 4GB.
With these thoughts in mind, let's
look at a few memory devices.
Continued... We gathered up nine different devices, all 1 GB or
larger, from eight different manufacturers. All
these USB flash drives are readily available,
and all cost under $90 (with 1GB devices
typically costing less than $50).
Note that we chose these units pretty
much at random. Several (Crucial, Sony, and
SanDisk) were supplied by the manufacturer. The
rest were either purchased retail or online.
While some of these products are
quite plain, others offer unique features. Let's
take a brief look at each one.
Apacer Handy Steno HT203
This is one of the larger memory keys. The cap
is permanently affixed by a wire. It also comes
with a handy docking cradle, so you don't have
to hunt around the bottom or back of your PC for
a free USB port.
Corsair Flash Readout 2.0GB
The tiny BCD (bistable cholesteric display)
readout lets you know exactly how much capacity
you have. It's otherwise fairly ordinary.
Crucial Gizmo Overdrive
Crucial ships this speedy, compact little unit
that looks quite ordinary.
The OCZ USB stick offers a hard, metallic shell,
but is otherwise undistinguished. Continued...
This white model is easy to spot and is also
Patriot Xporter XT
This is the only 4GB unit we tested. The
rubberized shell is hard to lose, but is also
bulky. It's cost-effective for a 4GB unit, and
is fast to boot.
Sandisk Cruzer Titanium
You'll never lose the cap on the Cruzer, but
it's the priciest 2GB model we tested. But you
get what you pay for.
Sony MicroVault Tiny
Sony accurately calls this USB key "tiny." It's
also very, very easy to lose. But small is still
pretty cool, and it's not particularly
Verbatim Store n Go Pro
This blue, 1GB unit looks a bit different, but
the actual shell design is pretty standard. The
Pro version shown here ships with data
encryption software. Continued...
We tested these USB keys on the system we built
for Windows Vista.
The system has 2GB of system memory and is
running Windows Vista RC1 with the latest
Setting up and testing for ReadyBoost
is easy. When you first plug a USB memory key
into a Vista system, you'll see the following
Click "Speed up my system." Vista
will test the USB key's performance, then pop up
a property sheet. If the USB flash key is
ReadyBoost capable, you'll see a property sheet
that asks you if you want to use ReadyBoost.
Just check the "Use this device" radio button to
enable ReadyBoost. You can also adjust the size
of the ReadyBoost cache file.
If Vista's flash memory test fails,
then you'll see the property sheet, only this
time you're informed that the device isn't fast
enough for ReadyBoost. You cannot turn on
ReadyBoost if Vista believes your flash key is
too slow. After all, why would you want to
slow down your system?
So which of our nine USB flash memory
keys work with ReadyBoost? Drum roll, please.
|Apacer Handy Steno HT203
|Corsair Flash Readout
|Crucial Gizmo Overdrive
|Patriot Xporter XT
|Sandisk Cruzer Titanium
|Sony MicroVault Tiny
|Verbatim Store n Go Pro
Of our nine USB keys, six pass
Vista's ReadyBoost test. Three don't. It's not
really surprising that the lowball unit—the
Patriot Xporter 2GB at $38—doesn't pass. But we
were a bit surprised that Corsair's pricey
Readout didn't either. The price/performance
king is the Patriot Xporter XT, with 4GB of
storage for about the same price as some 2GB
Read our DVD Burner Roundup.
The most convenient USB key is the
Apacer, with its USB docking cradle, while the
tiny Sony model and the retractable Sandisk
offer their own unique advantages.
We make no claims as to how fast these units
read and write large volumes of data. But
clearly, not all drives work with Vista's
ReadyBoost, and we suggest steering away from
the low-cost, 2GB models, just as a rule of
thumb. But as we've seen, pricey units may not
pass Vista's ReadyBoost test, either.
We fully expect other types of USB
devices to arrive on the scene, specifically
designed for ReadyBoost. But a fast flash memory
key can serve double duty, allowing you to
transport essential data and speed up Vista.