ccdconfig and Linux mdadm

[Maciej Suszko]

On Thu, 03 Jul 2014 13:07:07 +0200
Stefan Esser <se at freebsd.org> wrote:

> Well, you should first check whether the Ext3 file system has been
> created with parameters that are compatible with the ext2 driver in
> FreeBSD (which has grown some Ext3 extensions, but many are missing).
> 
> But AFAIK, the ext2/3 tools are direct and full ports of the Linux
> versions, and they should just work on file systems that the FreeBSD
> kernel does not support.

ext3 partition created directly on disk is recognized under FreeBSD -
simple checking `file -s /dev/ada1s1` and `file -s /dev/sdb1` give
similar results. When using ccd - device is seen as data, as there was
no filesystem.

> OTOH, I'm not sure, whether the parameters to ccdconfig are correct.
> A chunk size of 512KB does not match the parameter 512 in ccdconfig,
> AFAICT (512 sectors == 256KB). But this should not affect reading
> the super-block, which ought to be in the first chunk, anyway.

Tried setting ileave to 1024, using CCDF_NO_OFFSET - differet
combinations but with no luck.

> You may want to dump the raw data from the md/ccd device and compare
> results under Linux and under FreeBSD. This may give some insight,
> why fsck.ext3 does not find a valid super-block ...

I dd'ed first 1MB directly from md0 and ccd0 - MD5 checksums are
different.

> Just my 2ct - I'm not using ccdconfig myself ...

Thanks for suggestions.
-- 
regards, Maciej Suszko.
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