Lpc2000

Gus wrote:
> Hi,
> 
> ALFAT chip does save both FAT tables (if media is formatted with 2 
> tables) so if one got corrupted the second will be fine. I can't see 
> how FAT can be a problem! If you lose power on ANY file system you 
> will lose data. Simply close all open file handles and no data would 
> be lost.

There are file system layouts that avoid that problem - transactional 
ones, for example, tend to have a commit operation. If the power fails 
before you commit, or during the commit, then when it comes back up the 
filesystem is untouched - it was as it was at the end of the last 
successful commit. Changes made since that commit are lost, yes, but 
they weren't comitted, so the filesystem has not yet "promised" their 
safekeeping, and the existing data is never mangled due to filesystem 
inconsistency caused by the power failure.

Log-structured and journalling filesystems have this property - and log 
structured file systems can be good for FLASH memory, too, since they 
tend to spread writes out evenly!

However, they're not as widely supported as FAT, by any stretch of the 
imagination. So good for local storage only, rather than interchange, in 
general.

ABS

-- 
Alaric Snell-Pym
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