Re: Writing frequently to NAND - wearing, caching?

[Martin Egholm Nielsen <martin@egholm-nielsen.dk>]

Hi,

>>I have an application which may need to write states frequently to my
>>nand-fs in order to have these states in case of powerdown.
>>But I'm a bit concerned about wearing the nand if I write to frequently.

>>So, if I only need to write, say, 100 bytes every second, how often will
>>this actually be flushed to the nand?
>>Is there a maximum commit/flush frequency built in the driver? Or can
>>this be configured?

> It depends on what fs you're using.
> With YAFFS, and I believe JFFS2 too, there is no reason to worry about flash 
> "wearing out".  I have done accelerated lifetime tests on NAND using YAFFS 
> and in one test wrote 130GB to NAND without any data loss, bad blocks 
> happening etc.
Now, that's a lot :-)
I'm using JFFS2 - so hopefully you're right...

> The NAND writes whenever the file system tells it to, so again your question 
> is FS dependent, but all file systems that are NAND-friendly should handle 
> the load you mention with no problems.
And that is JFFS2 - but since it's a journaling fs it must commit the 
journal, as well, every now and then...

// Martin