I2O vs. Mass Storage Modes on Dell Perc Controller

[Questions]

On 5/11/06, Chad Leigh -- Shire.Net LLC <chad at shire.net> wrote:
>
> On May 10, 2006, at 11:57 PM, Questions wrote:
>
> > I just installed 6.1 on a Dell PowerEdge 1850 and the RAID adapter was
> > initially set for Mass Storage mode.  I read that I2O mode is a better
> > mode, so I flipped it to I2O, and the machine booted fine.  For some
> > reason this confuses me.  I would assume that my changing the
> > emulation of the RAID Adapter would cause the machine to no longer
> > boot.  Am I wrong in this assumption and switching between emulation
> > modes should not affect booting?
>
> Disclaimer:  I probably don't know what I am talking about and am not
> familiar with the various modes of the Dell RAID controller etc.
>
> Why would you expect it to affect booting?  I suspect that the
> machines BIOS makes the RAID available no matter what the mode and
> that the boot happens on the "bios" disk (through a "bios" interface).
>
> Again, this is not my area of knowledge but that is what I am guessing.
>

I really can't give you a good answer :)  I think it's just an
assumption based on ignorance.  I've had alot of problems in the past
with booting, hard drives, etc so I think it was natural for me to
think a change to the array like that would affect booting.

I would agree with your point, that the BIOS would make the raid
available no matter what the mode is, but I read something in the Dell
docs that I2O required Dell Drivers.  I think that's what also
triggered the assumption of breakage :)

http://support.dell.com/support/edocs/storage/RAID/66JVW/BIOS_Utl.htm#Objects_Menu
(Scroll down to Table 4 under Emulation) it mentiones the difference
between I2O and Mass Storage.  One needing Dell drivers specifically,
the other needed Dell Drivers or OS drivers.  That was the natual
progression for me to think that if I changed this setting, it would
use a different driver, thus affecting the bootup.