External array showing as /dev/sda

Matt Domsch Matt_Domsch at dell.com
Sun Mar 21 23:22:04 CDT 2010

On Sat, Mar 20, 2010 at 03:17:52PM -0400, David Hubbard wrote:
> Got a PowerEdge T510 with internal raid
> plus an H800 controller hooked to an MD1200
> external array.  Trying to install centos;
> raid controllers are 
> bus 2 device 0 internal
> bus 7 device 0 external 
> During setup its identifying /dev/sda as
> external storage which I don't want.  Is
> there anything I can tweak to make it
> detect the storage in an order that 
> results in the internal being /dev/sda?

Aside from the great suggestions in this thread already (install with
the external enclosure disconnected, make sure BIOS boot order is set
to use the internal disk first, set up your initrd to load drivers for
the internal disk controller first), there's yet another trick which
Dell included in Anaconda exactly to handle this...


The interesting part is this kickstart directive:

part /boot --fstype ext3 --size=1844 --onbiosdisk=80 --asprimary

where 80 is the (hex) value for the first int13 disk.  And of course
you set the int13 disk order in BIOS SETUP (or using DTK).

The magic bit is that you really want to use parted or fdisk to first
create an empty partition table on every (logical) disk in the system.
You don't want to just write zeros to the MBR of every disk.  parted
and fdisk know how to fill in a unique signature in the appropriate
MBR field, which anaconda uses to recognize and pair up the BIOS list
of disks with the Linux list of disks.


Matt Domsch
Technology Strategist, Dell Office of the CTO
linux.dell.com & www.dell.com/linux

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