I was not thinking ESD as I have designed such circuits in both bipolar and CMOS processes. Rather I was thinking more of an internal effect on the short traces of the internal circuits or possibly the effect of stored charge on the floating gates. My mistake for not being clear. And I was thinking disk drives would be more sensitive (I have also worked in that industry years ago doing read/write electronics). The domains are very fragile and it is only the high amount of error-correction that gives the reliability. Xray machines traditionally have had large magnetic fields, but I'm not familiar with todays airport scanners. Just that I would trust my flash card over my disk drive in both mechanical and electrical robustness. My co-workers, who just came from Maxtor, quoted the rate of domain failure with temperature, it is quite high. The only real way to test the effect of Xray machines would be to look at the failures before error correction. Both flash and disk drives have large error correction. Temperature has a major effect on magnetic domain lifetime. I now backup everything on multiple drives and keep some drives offline and cool. Just having the drive idle in a hot case is causing domain failures to occur. Securely erasing a drive is not the same issue as subtle loss of data over time.
Call me paranoid, but long term reliable storage is only achieved through a lot of redundancy. Probably a case of ignorance is bliss. Todays drives have the head flying a few microns above the media. It is truly amazing the technology works at all. Often with laptops, a slight bump can cause a short head-media encounter, creating dust that later, gets in the wrong place at the wrong time. Maybe I should get out my kodachrome... In the mean time, I buy some new drives every year or two and create multiple backup copies. Not only that, I have two identical machines, I can move the main drive (or clone) to the other machine and everything runs . I can't tell you the number of times that has saved my butt. (mostly because of pilot error.) It seems the only way to get long term reliable storage involves constantly moving data to newer media. If I am traveling, and I have photos I don't want to loose, I copy to the laptop, and leave them on the flash card as much as I can. Wayne * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
