Dodgy battery...

Thats what kills'em in the end

Owen

This could be true if they had batteries

As far as I know none of the USB flash drives have volatile memory. They all have non-volatile memory.

The main issue being with them that they have a lifetime limited by the number of write cycles.

This may of interest to anyone wanting to know how they work:
http://www.usbmemorysticks.net/flash-drive-technology

Steve,

there are small capacitors in the 'stick' that hold the state of the 'disk' controller...when they start to go, the stick (despite it not having used the requisit read cycles) will start to fail..

Owen

A link to back up that statement would be useful.

http://www.buzzle.com/articles/how-does-a-flash-drive-work.html

The disk controller is a small risc CPU - that has a small amount of RAM to store the parameters in. thats the bit that holds the 'format' of the disk - when that goes. well you can guess the rest...

As all the read/writes are handled by it, they cant use flash memory for all its registers.

they're totally fascinating little beasts

Owen

Reminds me of a chip I designed a few decades ago !

I wish I had more time. I followed the link and on from there. I didn't find anything suggesting the capacitor was a problem. I'd be surprised if a low V capacitor did anything more than just leak faster than it should, and a regular re-charge should solve that.

I did notice possible problems with removing power at the wrong time though. Incorrect "remove device" and power fluctuation specially in NZ make me wonder whether that was the problem.

It's working fine now....for now

This raises the question of whether a pen drive is better than an SD card "reader" and an SD card. I use the latter for backups. (same card as my camera uses).

Indeed it does... quite often with these devices simple use ensures they work for a long time...

Owen

I don't know why I didn't think of this before.
It MAY have been the problem.

I noticed on an SD card packet "Warning: Avoid static discharge to pins as data may be lost".

Maybe the drive got zapped.
Certainly worth grounding yourself before touching them, and avoiding touching the pins.

owen

Can you clarify whether pen drives or SD cards are different in their ability to function reliably? If they are different, which is better? And should anyone ever use steady-state memory instead of (revolving) drives of a PATA or SATA variety, even when they're finally cheap enough?