Installing debian etch (40r4a) on a Dell PowerEdege 1950 with SAS disks was not to easy. Debian crashed the fist reboot after the install, because of not loading or finding the correct module in initrd. The second issuse was swaping the drive from sdb to sda.
This is how I fixed it:
Don’t restart after installing debian. When the reboot prompt shows switch to vt2 (Alt-F2).
Edit /etc/initramfs-tools/modules with the output from lsmod, in my case it was mptsas. Next you need to edit /etc/fstab and /boot/grub/menu.lst so that sdb is changed to sda.