> Date: Wed, 17 Nov 1999 07:45:32 -0500
> From: TenThumbs <tenthumbs@cybernex.net>
>
> > 8 meg block groups imply you're using 1k blocks. 32 meg block groups
> > imply you're using 4k blocks. E2fsprogs 1.18 automatically creates
> > filesystems with 4k blocks when making large filesystems, but most folks
> > have filesystems created with earlier versions of e2fsprogs which used
> > 1k blocks by default, and so there are many filesystems using 1k block
> > sizes out there. That's why I said 8 megs or 32 megs.....
> >
>
> Doesn't this change in e2fsprogs make it harder to recover data from
> a corrupt fs since there's no obvious way to know where to look for
> backup superblocks.
>
> Yes, there is that downside. We should have put at least one set of
> backup superblocks at a fixed location, but that's one of the things we
> didn't do when we were originally designing ext2. Hmmm... it may be
> possible to put a fixed superblock on larger-sized filesystems by having
> mke2fs create a .backup_superblock file, which make life easier for some
> folks. (Folks who decide they desparately need the extra space back can
> just delete the file.)
>
The superblock at the first 32M should always be there.
It would be the first backup with 4k blocks and the
fourth with 1k blocks (or the second with 2k blocks?).
There may be a problem with larger block sizes than 4k,
but that is not an issue currently.
-- Daniel Taylor Senior Test Engineer Digi International danielt@digi.com Open systems win.
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