Re: Finding parameters of existing ext2fs partition

[Pierre-Philipp Braun <pbraun%nethence.com@localhost>]

> Question is how to determine what this format is for an already existing ext2fs filesystem, either from base system or from e2fstools package.

One solution would be to reboot with a GNU/Linux live/rescue system and check from there with `tune2fs -l`.

The other way around, I do deploy NetBSD systems with an ext2fs root from GNU/Linux and I need to disable a few EXT2 features that are not recognized by NetBSD.

By default, when creating EXT2 from Lignux, one would get

	Filesystem features:      ext_attr resize_inode dir_index filetype sparse_super large_file

I disable those two features

	mkfs.ext2 -O^dir_index,^ext_attr

so in the end I get

	Filesystem features:      resize_inode filetype sparse_super large_file

> Problem is when I write to an ext2fs filesystem from NetBSD, I may get errors, especially with a big, complicated write that would occur with "git pull".

I got no errors and use it even in production - it is just very slow - luckly it's mostly an idling dedicated box.

The only issue I have is with GIT also.  I cannot review e.g. `git status` nor anything, although nothing crashes here.  Apparently GIT is using some file-system features that we don't have.  Otherwise I am good, everything works.

> My hypotheses is that the filesystem was formatted from FreeBSD with their default -r 1, comparable to -O 1 in NetBSD.

If you're playing with FreeBSD, why don't you just use FFS?  Theirs and ours is pretty much compatible.

> I want to create a Linux ext2fs that can be safely written to from NetBSD.

As shown above, I prepare the fs from GNU/Linux.  I've documented it here:

http://pub.nethence.com/bsd/malabar
http://pub.nethence.com/bsd/ext2fs
https://pub.nethence.com/bin/bsd/netbsd.install.bash.txt

as for FreeBSD with UFS2 is here:

http://pub.nethence.com/bsd/malabar.freebsd

--
Pierre-Philipp