Power Down

David Woodhouse dwmw2 at infradead.org
Wed Dec 8 04:54:12 EST 1999

Orono at m-sys.com said:
> The only way to be resistant to power failures in the file system
> level  is to use a log-structured file system.

> I heard ext3 is log-structured but I am sure one of the Linux guys here
> knows more about this, 

ext3 is a journalling filesystem. I believe that it's not log-structured. 

Journalling is sufficient for protection from power failures. Stephen, 
would you care to elaborate on the difference?

> Any other file system  that takes power failures into account, (I am afraid 
> to guess NFTL ????).

I believe that NTFS is also journalling but not log-structured.

> Some of our customers use their own home brewed LFSs and do it successfully. 

Personally, I'm inclined to believe that we should run a filesystem directly 
on the flash device - rather than faking a block device and running a 'normal' 
filesystem on top of that. 

I've been rushed off my feet here with other things for a while, but as soon as
I get back to it, after I've fixed the NFTL and DiskOnChip Millennium support,
that's what I'm intending to look at.

If you're running ext2 on a DiskOnChip you should mount it with the noatime 
option if you can - this will eliminate a lot of write activity.


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