Many problems can be solved by a simple structured approach, analysing the symptoms, finding the cause and determining the solution. The following is an excerpts from the Multi Disk HOWTO.
Cannot find disk
How to find what drive letter corresponds to what disk/partition
Remember Linux does not use drive letters but device names. More information can be found in section "Drive names".
Cannot partition disk
Most likely wrong input to the command line for
fdisk or similar tool.
Remember to use
/dev/hda rather than just
do not use numbers behind
hda, those indicate partitions.
Cannot format disk.
Strictly speaking you format partitions not disks.
Make sure you add the partition number after the device name
of the disk, for instance
/dev/hda1 to the command line.