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Wrong! | 283 comments | Create New Account
Comments belong to whoever posts them. Please notify us of inappropriate comments.
Wrong!
Authored by: tiger99 on Wednesday, November 07 2012 @ 01:20 PM EST
Write cycles are just as damaging as erase cycles. And, it is certain disreputable manufacturers of storage products, basically only packagers, who are claiming 100k cycles. The chip manufacturers generally claim 10k.

Now with wear levelling it may seem that they will last quite a long time, but it depends entirely on how much free space there is on the device. If, in the extreme case, only one sector remains free, 10k writes will kill it. I have seen some other incorrect calculations not so long ago, which also made the same error of using total device capacity in the calculation. It is not, it is always the free space that matters, for any solid state memory with wear levelling.

Nevertheless, if care is taken to ensure that there is always a large amount of free space, say 50%, and the kernel "swappiness" is set to minimum, solid state storage devices, such as USB sticks or SD cards, are fit for the envisaged purpose, where a life of a few years is all that will be required. But ferroelectric RAM (FRAM), which is non-volatile and has a much larger capability for write cycles (also per byte, not per sector) is coming along and when its storage density becomes comparable to flash, the limited life will largely disappear. I am not convinced that anyone knows yet just how many write cycles a FRAM cell will tolerate, and whether it is infinite or just a very large number, but it is certainly much better than flash. And, it works more or less like RAM, i.e. almost as fast to write as to read, and every bit independently changeable. See here for example.

[ Reply to This | Parent | # ]

  • Wrong! - Authored by: DieterWasDriving on Wednesday, November 07 2012 @ 03:18 PM EST
  • Wrong! - Authored by: Anonymous on Thursday, November 08 2012 @ 08:51 AM EST
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