which file system for sd card - for Wiki

Fernando Martins fernando at cmartins.nl
Sun Jan 25 23:35:16 CET 2009

arne anka wrote:
> if it is not yet in the wiki, somebody should probably gather the bits  
>  from the archives and put it there -- it seem to be a rather recurrent  
> question.
I wrote the following text which I can put somewhere in the wiki. Since 
I'm no authority on the matter, I would appreciate feedback from the 
list beforehand.

I got a new SD card. Which file system is the best?

In general, vfat or ext2 are the most recommended.

Vfat might already be the fs in your card when you got a new one. It has 
the advantage of being recognised in many other systems. The data 
structures are simpler which might mean less writes on the sd-card and 
less code being executed (this statement should have some objective 
verification) and you'll find more tools available to recover 
information when you get errors.

ext is Linux centric but one of the most tested and tuned. It is also a 
faster file system than vfat (citation?) and most importantly, if you 
need, it supports permissions, which vfat doesn't.

What about file systems like jffs2 and ubifs, which are aware of flash 
card wearing?

SD cards, according to SanDisk specs, should have wear leveling logic, 
which controls the number of writes and remaps blocks as needed. 
Wear-aware file systems might actually play against the logic of the 
card are usually not recommendable.

What about journaled file systems like ext3?
The advantage is that it will maintain your data in a consistent state. 
However, the journal uses extra space and will impose more writes in the 
sd card, thus decreasing performance and wearing the card.

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