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RE: ext3 sync problem



Hi Andreas:

> On Sep 17, 2002  11:04 -0700, Hua Zhong wrote:
> > Thanks for the reply. Two questions:
> > 1. Could you give me a pointer to the patch that flushes ext3 journal
> > explicitly? I'd like an enhanced "sync" behavior that flushes
> everything to
> > the disk.
>
> This is done implicitly when lilo calls the FIBMAP ioctl.

I don't quite understand here. As I understand it the only interaction
between lilo (and any bootloader) and the OS is lilo loads OS and that's it.
What do you mean by "lilo calls FIBMAP ioctl"?

> > 2. Is there a way to sync metadata as well as data?
>
> It depends on what you mean, precisely.  The metadata is "synced" to the
> journal.  The problem is really that GRUB is ignoring the fact that the
> journal exists.  If the kernel were to mount the filesystem, or e2fsck
> run on it, then the metadata in the journal would be flushed to disk.

I mean sync everything to disk so GRUB can see the change after reboot. It
cannot be in the journal.

> > If this problem cannot be solved, I may have to go back to ext2. Yes it
> > takes more time to do fsck but or a 512M flash with 4
> partitions it takes 11
> > seconds which is not that bad - and ext2 is in general more stable and
> > faster....
> >
> > I'm also wondering how many people are using ext3 on flash. Is there any
> > better alternatives (like FAT maybe?)
>
> You are probably far better off to use JFFS2 or similar - it is a
> journaled filesystem explicitly designed for flash devices, so it does
> wear leveling and such (otherwise the journal + superblock will quickly
> wear out part of the flash).

Yeah I am already looking into it. I haven't played with it much. It
requires some MTD layers and I assume not everything is in the kernel (?).
Currently our flash interface is IDE (and flash is NAND I think). Does it
work with such an interface? Thanks.

> Cheers, Andreas
> --
> Andreas Dilger
> http://www-mddsp.enel.ucalgary.ca/People/adilger/
> http://sourceforge.net/projects/ext2resize/
>





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