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Re: Endurance




dwmw2@xxxxxxx.org said:
> For JFFS2, it's not as good, because JFFS2 will 'helpfully' merge data
>  pages as you write them. So the first write will take a similar
> amount as  in JFFS (80 bytes), but the second node written will
> contain all 20 bytes  of data and obsolete the original one. The third
> node will contain 30  bytes, etc.... up to the 409'th write which will
> contain 4090 bytes. 

> If your data are uncompressable, then in 40 minutes you'll create
> about a  page of data but churn 80 + 88 + 100 .... = 850KiB of flash.
> If you get 2:1  compression that'll only be ~440KiB, but it's still a
> lot more than the 29  that JFFS would take. This is a behaviour
> pattern that JFFS2 really doesn't  handle very well.

As part of the portability cleanups prompted by the eCos port, I've just 
fixed this. JFFS2 ought to behave as well as JFFS in this respect now. 

--
dwmw2



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