Writing frequently to NAND - wearing, caching?
Martin Egholm Nielsen
martin at egholm-nielsen.dk
Mon Feb 7 03:33:48 EST 2005
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
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