Quote:
Originally Posted by j.p.s
...books reappear after a reboot, new books disappear after a reboot, setting changes don't stick, etc. These are all symtoms of a worn out flash memory mounted readony. When other possibilities are eliminated, flash wearout is the most likely explanation.
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I would place my vote for faulty software over worn out flash memory. Each bit of flash memory of the type that is built-in to inexpensive devices is typically good for over 100,000 write operations. Flash memory has "wear leveling" as well - so when one block is freed it is not usually overwritten immediately, a different block is used instead. And with these devices having gigabytes of flash, the chances of a given bit being overwritten greater than 100,000 times is basically non-existent.
One thing about flash memory that may come into play for eReaders is that it is not designed for long term storage. If you write a bit and then it sits there, unchanged, for a few years (5 to 7 typically) it may "lose its charge" and get corrupted. To keep this from happening the operating system can periodically refresh the flash memory (re-write the bits with the same value they already contain). This refreshes their charge and their memory is good for several more years. eReaders may not be sophisticated enough to do this compared to much more powerful (and smarter) computers. So the ebook that has been sitting there on your eReader for years may start experiencing some corruption. Or the area of flash that "remembers" if the book has been deleted or not may lose its charge. This does not mean the flash memory is bad. It means that the Operating System that manages the flash memory is dumb. You write to that drained bit and bingo, it's as good as new. "Good as new", unfortunately, may mean that it forgot what it used to contain before being refreshed to good as new status.
BTW, thumbdrives and microSD cards are subject to this same gradual loss of charge. So are SSD's, but those use higher end flash media and are somewhat less susceptible. This does not mean the flash memory is going bad. It means that it was used for long term storage - something it was not designed to do. If you want data to store for a longer period of time, store it on a magnetic hard drive. Those have their own problems - motor issues, head crashes, etc. - but pure data retention time is longer than flash memory. If the motor gums up and won't spin up, you of course will have issues accessing that still-stored data. That's why you pay good money to "data retrieval services" to retrieve your data.