[hfs-user] Problems with HFS+ empty volume...

Mark Day mday@apple.com
Fri, 5 Apr 2002 08:59:35 -0800

On Thursday, April 4, 2002, at 05:44  AM, Entwicklung wrote:

>                   I just wanted to check if anyone knows if it is 
> essential to have an empty B-Tree for the attribute and startup file in 
> an HFS+ image. In case of HFS these weren't present in my image. In 
> case of HFS+ I've increased the node size of the catalog to 4kB and 
> included the other changes as discussed. Only thing I haven't done is 
> to create a B-Tree for the attributes file and the start up file - in 
> short I'm not writing anything into the image for these and have set 
> the respective extents, sizes setc. to 0 in the Volume Header. Is this 
> right or should these be present in the image as 'empty' B-Trees ???

Just leave them with zero length and zeroes for the extents.

The Attributes B-tree has never been used, nor even fully designed; it 
was left as a placeholder so we could extend the volume format in the 

The Startup file would typically be used for extra code or data needed 
early in booting (perhaps before you've loaded enough code to search the 
catalog or extents B-trees).  It typically wouldn't be a B-tree at all.

> The only problem is that I don't have any utilities to create 
> sample HFS+ images which I can cross-check my image with.... Disk Copy 
> on my iMac with MacOS 9 creates only HFS-Volumes by default

In Mac OS 9, use Disk Copy to create a read/write disk image that is at 
least 32MB.  That is the minimum size volume that Mac OS 9 will format 
as HFS Plus (though it should recognize smaller volumes).