I'm about to automate the installation of Debian by using the preseed mechanism (preseed file added to initrd). The computers to be provisioned have multiple SATA disks.
I would like to specify in the preseed file precisely what partition to put on what disk. This is possible, of course, by specifying the associated device files (sda, sdb, sdc). However, if I understand correctly, the association between disk and device file is not a priori defined in general, and may even change after rebooting in certain situations. I am especially concerned about usb sticks or other portable hard drives. I have encountered such a situation myself, when the usb stick was /dev/sda during installation from that very stick.
So, how do I ensure, that the right partition is placed on the right disk, each time the preseeded ISO image is used for installation?