[CentOS] aacraid hard/firmware differences?

[Alain Spineux]

On Jan 8, 2008 1:06 AM, Les Mikesell <lesmikesell at gmail.com> wrote:
> Joseph L. Casale wrote:
> >> Does anyone know what controls this or if it is just a hardware or
> >> firmware version difference?
> >
> > I have seen this before with different controllers. I believe it to be as you think, differences in controllers and how they access the hardware.
> >
>
> I could understand that between different types of controllers - or
> maybe even with a different setup.  These appear to be the same with
> individual drives set up as separate volumes in all cases.

In the past, when IDE/ATA drive was the king, their was lot of
different cylinder mapping
(LBA) to break the successive 32Mo, 512Mo, 2Go ... barrier
Depending the BIOS options, the drive had a different geometry, then when
changing these options, or changing of motherborad, linux was still working,
but fdisk was complaining about "cylinder not on a boundary". Do you remember ?
To avoid this linux kernel added smart geometry detection, looking at the
partition table, linux was guessing the geometry used at partitioning time.
But sometime it was wrong and the disk was unusable. But not really, because
usually only the first controller was doing smart geometry detection, and
the second one was still using the geometry given by the BIOS.
Then switching a drive from first controller to the second one, or
maybe from SLAVE
to MASTER was able to change the reported disk geometry.

Then my question. Is it the same controller or the same linux distribution ?


>
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>    Les Mikesell
>     lesmikesell at gmail.com
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-- 
Alain Spineux
aspineux gmail com
May the sources be with you