grub does not boot when disk order changes

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http://serverfault.com – My BIOS has some problems and sometimes boot order of disks changes. I thought that if I insall grub on to the MBR of second data disk, it may boot. First disk(sda) is for boot and operating system, second disk(sdb) is for /var. All partitions are labeled and fsck has labels as partition references. I have install grub on to MBR of second disk by "grub-install /dev/sdb". It installed succesfully. However when I change the order to second disk to simulate, I got: "Error 15: File not found" on grub stage. | root (hd0,0) | | kerne (HowTos)