On 09/27/2010 01:29 PM, Henry Vermaak wrote:
Any disk with on-disk cache is susceptible to data loss
A flash card need to have a cache. The pages of the flash medium are
several MB. you can erase a page only completely, not partially. So
whenever you overwrite some data by writing just a sector (usually 512
Byte) quite complex things need to be done internally, as overwriting in
place is not possible. So a cache is used to collect some changes and
handle the on block for better speed and less wear out.
Of course the cards will write unused parts of the storage when possible
(not creating a problem with power down in that case), but if all free
space is used, some complex housekeeping needs to be done copying pages
and erasing some.
-Michael
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