Just because you have a 2.0 USB flash memory drive doesn’t necessarily mean that it will be lighting fast. In the production of your 2.0 flash memory drive there are several factors in the BOM (Bill ofMaterials) that can affect the speed of the device.
If you just use your USB flash memory to download music or transfer normal work files you probably would not notice the difference in speed between two 2.0 drives. But some applications like Windows ReadyBoost require specific random writing speeds. Microsoft says those random speeds are 2.5MB/sec. for random reads of 4KB of data, and 1.75MB/sec. for random writes of 512KB of data. Those speeds are not exceptionally fast but in my business I have run across many units that cannot reach those levels.
Why?
You run into two major costs when building a drive. They are the I/O Controller, and the type of memory chip used.
The I/O Controller as the name implies handles the input and output of information between the USB drive and the computer it is plugged into. The number of channels the I/O controller has acts as a speed regulator. The more channels that are moving the data, the faster the drive performs.
The type of memory used in the drives is either expensive SLC (single-level cells) or inexpensive MLC (multi-level cells). SLC memory has higher transfer speeds (about twice as fast) and lower power needs. MLC memory is typical in today’s USB flash memory due to its cost.
So how does a typical consumer know which USB flash memory to buy to get the fastest speeds? You really don’t know – my advice is to buy the more expensive drive since it is the cost of the memory and I/O Controller that make up a significant portion of the production cost.
PS: Just for giggles (actually I was checking a competitor) I bought a 1GB no-name 2.0 flash memory unit off EBay for $1.99. Guess what? It couldn’t achieve the base speeds for ReadyBoost.
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