ESX on PowerEdge 1850 - install fails the second time

[Shane Presley]

We're installing ESX on a PE 1850 with a Perc4 controller. There are
two physical disks, mirrored, to make a single logical disk.

The first time I install ESX, everything goes fine.  But if I
re-install ESX, the install procedure reports that it sees two hard
drives (/dev/sda and /dev/sdb).  If I select a "new" install, it
deletes the partitions on both sda and sdb, and installs to sda. But
the next reboot hangs, with a grub error.

This seems to be reproducible.  The first install of ESX is fine.  But
if I try a re-install things go bad, and it seems to center around
seeing that second drive (sdb).

Any thoughts what might be causing this?
Thanks