Re: HFS and FAT FS-resizing returning soon (but to a separate library)

[Chris Murphy]

On Jan 24, 2012, at 2:45 AM, Jim Meyering wrote:
> 
> Thanks.
> The code (I think I saw this in non-parted code, too) interprets jhdr_size
> as the disk's sector size.
> 
> Parted's HFS-resizing code was written for 512-byte sectors, with
> numerous stack and heap structures hard-coded to that assumption.
> That is why it rejects any attempt to resize a disk whose sector size
> appears to be different from 512.

Apple's diskutil command reports sector sizes as 512 bytes. To my knowledge, 
VDI's don't support anything except 512 byte sectors. And even if there is a 
passthrough, the disk itself is 512e, not 4Kn.

I don't know what the threshold is, but when I create a new smaller VDI 
(350GB), and format it with Apple's Disk Utility, the jhdr_size is 512 bytes. 
If the VDI is larger (~2TB or more), again formatted with Apple's Disk Utility, 
the jhdr_size is 4096 bytes. Same virtual machine, same underlying drive.

Chris Murphy