choice of flash file system for large read-only volume

Ricard Wanderlof ricard.wanderlof at
Thu May 17 17:06:40 EDT 2007

On Thu, 17 May 2007, Hamish Moffatt wrote:

> What would be a good choice of file system for this application? Does it
> come down to JFFS2 versus YAFFS, or are there other alternatives?
> I understand that JFFS2 mount times are proportional to the size; mount
> time isn't critical to me but I would like the system to boot as quickly
> as possible. Is YAFFS better in this regard?

One option you might consider if you have enough ram, is simply to make a 
copy of a read-only file system such as cramfs in the flash, and upon 
boot, copy it from flash to ram (skipping bad blocks of course), and 
running it from there. Of course, you cannot write to cramfs, so that 
would not be a good idea during development.

Since a straight copy from flash to ram can be reasonably fast, and 
accessing cramfs in ram is quite fast, boot time is shorter to or 
comparable to having the root partition directly in the flash as a jffs2 
partition, in my experience.

Ricard Wolf Wanderlöf                           ricardw(at)
Axis Communications AB, Lund, Sweden  
Phone +46 46 272 2016                           Fax +46 46 13 61 30

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