Mylex PCI to Ultra SCSI RAID Controllers DAC960PG Installation Manual page 29

Enable 8GByte or 2GByte Drives
This setting affects how the BIOS reads the disk drives for the boot partition.
Drive geometries can be toggled between 8 GB and 2 GB. The default is 2
GB. When the drive geometry is changed, the drive should be formatted at
the operating system level.
Caution
Changing this setting after data has been stored will
make the data unreadable. If you have already
configured your array and have stored data, you
should not change this setting.
The default BIOS geometry of the controller is set to 2 GB. This means that
the BIOS can only access the first 2 GB of any drive that has been configured
on the controller. This is adequate in most applications, since BIOS is only
used to boot the operating system. However, it does mean the operating
system must be installed in the first 2 GB of the capacity of the configured
drive. If this is not adequate, the BIOS geometry can be changed to 8 GB,
allowing the BIOS to access the first 8 GB of capacity.
As a rule of thumb, select 8 GB geometry if the following two cases apply:
1. You have a system (RAID) drive that is greater than 2.145 GB in
capacity.
2. The DOS/Windows compatible partitions could be located in an area
above the first 2.145 GB.
Otherwise the 2 GB option is fine.
Manual No. 775012
Controller Start-up
4-3