Mac UFS partition unreadable

[Charles Sprickman]

On Sun, 19 Dec 2004, Bram Van Steenlandt wrote:

> Hi,
>
> I use both mac and freebsd and would like to have the abbility to use my 
> external firewire drive on both plattforms.

There is another way to do this, but it's a tremendous hack.  That said, 
I've been doing it for more than two years...

>From what I gather, the partitioning is the real issue.  BSD can't read a 
OS-X partition "map" (for lack of understanding, I'll use that word), and 
vice-versa.

Here's what I did...  I had a large drive and I first ran disk utility 
under OS-X and left about half of the space unallocated.  I went ahead 
with the normal HFS+ formatting.  Then I ran "pdisk" under OS-X to see 
where the partition started and ended, same for the free space.

I then moved the disk to FreeBSD.  To grab all the OS-X labelling, I did 
"dd if=/dev/da0 of=osx-label count=6".  Hold onto that file.  Next I ran 
the BSD fdisk and disklabel.  I took the OS-X start/end numbers and 
plugged those in and labelled that as unused in BSD.  I then made a new 
partition with what was the "unused" area of the drive under OS-X.

I then ran the following command: "dd if=/dev/da0 of=bsd-label count=1" 
and saved that file.

So the disk at that point could be mounted under FreeBSD.  But if you take 
it back to OS-X, no-go, since it can't make heads or tails of the label.

To make this vaguely usable, I "switch" the disk from one "mode" to the 
other.  So if I've been using it under FBSD and want to use it on the Mac, 
after unmounting it, I do:

"dd if=os-x-label of=/dev/da0"

Then if I unplug it and throw it back on the Mac, all is well.

When I want to use it on FBSD, before mounting I do:

"dd if=bsd-label of=/dev/da0"

And then it mounts.

Very hackish, but the only thing I could find.  I thought about FAT32, but 
since I needed to have HFS+ stuff on there that requires resource forks 
and other oddities on the Mac side, and on the BSD side I needed real 
perms, FAT32 didn't cut it.

YMMV, all that is from memory, but you get the gist of what's going on...

Charles

> This should be possible because both are BSD and both can use UFS.
> However when I plug an freebsd formatted drive into my mac he is rather 
> confused by first saying that he can't read this drive and I should format 
> it. Then when I try to mount it from the terminal he complains about the 
> superblocks, when I run some utils they sometimes say they can't determine 
> the partition type, also when I look into /dev there is nothing that 
> indicates that this drive has partitions.
>
> So I formatted the drive on my mac into UFS. Same thing happens on freebsd. I 
> did some googling and it appears to be so that this could be because of 
> little vs big endian. I am however rather new to freebsd and have no idea 
> what the difference is.
>
> So what can I do to have a drive readable to both OSes ?
> note:
> drive is 160 Gig seagate
> mac is running 10.3.5
> freebsd is amd 64 5.3 RELEASE
>
> mac supported disk formats are
> MS-DOS,UFS,HFS,HFS+
> I now that HFS or MS-DOS would work but then I have no support for 160 gig / 
> long filenames
>
> I'm out of inspiration
>
> Thanks In advance
>
> Bram
>
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