Re: [RESEND] Hard disk LBA sector count is not always the same

[DervishD <lkml@dervishd.net>]

    Hi Jeff :)

    Thanks for your answer, Jeff :))

 * Jeff Garzik <jgarzik@pobox.com> dixit:
> DervishD wrote:
> >    current capacity is 156299375
> >    native capacity is 156301488
> Hard drives have a feature that can reserve a certain amount of space 
> away from the user.

    Yes, I know, but the problem is that 2.4 kernels *does* reserve
that space but 2.6 certainly not, and if I boot into 2.6 and then
reboot into 2.4, then 2.4 *does NOT* reserve that space.

    By the way, the 'current capacity' is reported as the above only
if I boot into 2.4 from power off. As soon as I boot into 2.6, the
drive seems to be reporting the second number as the current
capacity (capacity_2). I've check the code in 2.4.29 and the
difference between the setmax capacity and the capacity_2 only
happens in that case, when cold booting into 2.4. Anytime 2.6 is
involved, the drive reports the same capacity in both calls
(idedisk_read_native_max_address_ext() and the one that gives
lba_capacity_2 its value).
 
> Linux IDE often does 'set max' to make 100% of the hard drive
> visible to the OS.

    See the paragraph above: if I partition the disk under 2.6 the
partition will have a bigger address than the one that will be
available under 2.4, and that can give errors while accessing that
extra sectors. What can I do? For technical limitations in my box, I
have to use 2.6 for repartitioning that disk (and I will be doing
that in less than a month) and this will lead to unaccesible sectors
when I boot back into my usual 2.4 kernel :(

    Moreover, I've googled a bit and my disk doesn't seem to have
this problem, so I'm worried about a disk failure :(

    Thanks again for your help, Jeff.

    Raúl Núñez de Arenas Coronado

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