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USB Flash Memory

It seems to me that USB "flash" memory is now just abut becoming mainstream after years of being looked at as a "geek" toy.  I had one when capacities were measured in tens on megabytes (I think it was a 16 Mbs in size) but nowadays they go all the way up to several gigabytes in size.  And they're not just "plain ole memory" any more - they come equipped to play MP3 and WMA files and attached to digital cameras.

In this review I will look at a few options open to those interested in getting onto the "flash" memory wave.

Capacity & Cost

Capacity and cost of these devices go hand-in-hand.  The larger the USB memory, the more expensive it is.  However, double the capacity doesn't mean double the price - in general, there is an economy in buying larger drives.  For example, a 128 Mb flash USB device will cost less and double the price of a 64 Mb drive and a 1 Gb drive should cost you a lot less than double the price of a 512 Mb drive.  Above 1 Gb and the economy of buying larger devices diminished, then vanishes and things become expansive.

Consider how much space you need - several factors are at work here:

  • Cost?  Obvious really.  However, skimping on storage space can mean that you threw your money away on a device that doesn't do what you want.
  • What do you want to store on the device?  If it's just a few files then a small device will suffice but if you are using it to store files relating to a project or using it as a backup media for photographs or applications then you will need more space.
  • How will your requirements change over 6 - 12 months?  Look at how you think your space requirements are going to change - these USB devices have a long life and it's a shame to have to replace a drive within months just because you bought the wrong thing.  
    As a general rule take whatever capacity you think you need and double it to be sure of having enough space on the key for data growth over a period of 6 - 12 months.
  • How do you plan to use the device?  Backup?  Storage?  Moving data from one PC to another?  Think about how you currently work with your data and how USB memory will fit in with that.

Features

Do you just want a plain USB flash memory device or do you want something that does more?  Do you want it to play MP3 and WMA (Windows Media Audio) files?  Do you want a digital cameral attached?  These are all cool devices and add very little to the price considering how expensive such devices were a few years back.  I have a 256 Mb Creative MuVo TX FM that can act as USB memory, audio player, mini recorder and mini FM radio but I must admit that I don't use it often as plain memory because the memory is full of stuff I want to listen too!  Adding more functions to a tool usually means that the common "boring" features don't get used in favor of the exciting features.

Don't get me wrong though, I really like multi-function USB memory devices, it's just I'm not disciplined enough to use them right.  If you like the idea of USB memory that does more then that's great, but don't be surprised to find yourself eventually buying two!

Performance

USB 1.1 is slowly being edged out by the faster USB 2.0.  High speed USB 2.0 products have a design data rate of 480 megabits (not megabytes) per second transfer rate.  This translates to about 60 megabytes per second.  This means that theoretically you could fill a 1 Gb USB memory device in about 16 seconds.  In truth, you don't get anything near that level of transfer.  Standard USB 1.1 full speed USB devices signal at 12 megabits per second (around 1.5 megabytes per second) which makes them much slower.  Transferring 1 Gb of data at the theoretical maximum limit would now take over 11 minutes!

Note:  To convert megabit to megabytes, divide by 8. 

Most USB memory devices will operate on either USB 1.1 or 2.0 ports but as the capacities become greater the slow performance of USB 1.1 becomes more apparent.  However, most people will be capable of upgrading their systems to USB 2.0 by the addition of a simple (and cheap) PCI adaptor card.

Note:  Adding a USB 2.0 compatible hub to a USB 1.1 port will not increase system performance to USB 2.0 levels. 

If your PC supports USB 2.0 then don't waste your money on USB 1.1 devices - you should be able to find USB 2.0 compatible flash memory devices for the same price as USB 1.1 compliant devices.

How do you know if your device is USB 1.1 or 2.0?  Well, it should say in the documentation but Windows XP will certainly tell you if you connect a USB 2.0 device to a USB 1.1 port:

How many?

How many USB memory devices you will want is a matter of choice and how you use them.  Some people would rather one or two 1 Gb devices while others would find a handful of 128 Mb devices more useful.  Again the best advice I can offer is for you to think carefully about how you think you will use the device.

Other Options

There are other options to buying dedicated USB flash memory devices.  These range from card readers for digital camera memory to full-blown external hard drives.  If you work a lot with a digital camera then perhaps a few additional memory cards in whatever format your digital camera takes and a card reader would be more useful to you because they would serve a dual purpose, especially since the cost of both the cards and readers are quite low, roughly equivalent to USB flash memory (however, be mindful of falling into the same rut as with Flash Memory/audio devices).

If you want a lot of space then an external hard drive attached onto a USB 2.0 or FireWire port is the best, most economical option.  However, these aren't the kind of thing you can carry around in a pocket (unless you have big pockets!).

Before I close, one other thing I want to address about USB memory (because I get asked this a lot) is about data security and robustness of these devices.  

First, security.  There are many devices out on the market that claim to be able to encrypt the data securely onto the device or that use some sort of password protection to control access - personally I wouldn't trust either of these functions because I've yet to see a manufacturer be clear about what the encryption is and how it works (both of which are vital pieces of knowledge for anyone wanting to make a security choice).  If security is important to you then I'd suggest that you use commercial-grade encryption (such as PGP) to secure the data or to compress the data using a product like WinZip or WinAce and use the security options contained in them to secure the data (both support recognized encryption algorithms).

Secondly, robustness.  USB flash devices are quite robust and have a long lifespan and can withstand dropping, keeping in the pocket and repeated insertion and removal from the USB port.  However, they are not indestructible, and some things that can damage them include:

  • Immersion in water
  • Heavy impacts/dropping them from a height/stepping on them/driving over them
  • Prolonged exposure to high heat
  • Dust and dirt

The memory in these devices is very stable and you can expect the data to be readable on these devices after years of storage and having not been plugged into a PC (they don't have any form of backup battery to worry about).  The estimated lifespan for most is quoted at 10 years.  If you have one that's not been used for some time (say a year or so) then I'd suggest that you copy the data off it and then back onto it, just to refresh the memory chips.

Be aware though that these devices are subject to data loss through deletion (accidental or deliberate), virus attacks and crashes as any other form of memory.  Also remember to follow any instructions on disconnecting such device from the system to avoid data loss.  Below I'm disconnecting a USB flash memory device from a Windows XP system.

Adrian Kingsley-Hughes
Last updated: Feb 21st 2005
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