Charles Manning wrote:
>On Tuesday 22 April 2003 21:18, liuke wrote:
>> 	Would you tell me how yaffs and jffs(2) realize their jounals?   Just
>> simply by copying pages or nodes? Are there journal files on disk?
>
>Basically, what journaling means in this context is that we update files by 
>writing "patch records" to NAND. THus, we never change the file structure so 
>the file can never be in a state which is unrecoverable.

I hope I've got this correct; these file systems are, loosely, based
on an older file system called the "Log Structured File System".  The
LFS was designed in the early '90s, in an effort to speed "both file
writing and crash recovery".  Obviously the reasons for using the
technology here are different, but the basic method employed is
similar.  You can get to the original, very readable, research paper,
here:

  http://citeseer.nj.nec.com/rosenblum91design.html

Hope that helps,
  Sam

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