[parted-devel] > 63 heads. Why does this keep coming up?

[Phillip Susi]

On 02/13/2011 01:28 PM, Curtis Gedak wrote:
> It might be useful to print a message indicating a problem with invalid
> CHS geometry, and that parted will write a geometry when edits are made
> to the partition table.
>
> What are your thoughts regarding informing the user about invalid CHS?

CHS is just leftover garbage from the days when dinosaurs walked the 
earth.  Nobody actually uses it anymore, so it doesn't really matter. 
If the existing CHS addresses are nonsense, then parted can hardly make 
it any worse, and so no harm will come from it.  I therefore don't see 
any reason to send the user into a panic warning them about it.

> TEST B SUMMARY
> --------------
> Parted also changes the disk geometry to a valid one when a new
> partition is created. Now that the CHS geometry has changed, fdisk no
> longer sees the original partition as cylinder aligned. I wonder if this
> change in geometry could possibly cause problems later on....

There actually isn't anything to change since the disk geometry is not 
stored in the partition table.  Parted just tries to guess what geometry 
was used to compute the existing CHS addresses from their LBA, and use 
that same geometry when it needs to compute a CHS address.  If that 
guess fails, then I believe parted just assumes the max values for heads 
and sectors when it has to write CHS values.