linux installer fails to see a sda1 after the drive was used in a raid

Stump the installer. Last week we had another challenging install at the local installfest in that most installer programs would not see the HDD sda. server did work but no desktop versions. after going home I found this link checked and verified and even and format and new partition tables the drive still thought it was part of the raid. sudo dmraid -E -r /dev/sda fixed it and then all installer programs seemed to work fine