On 2016-10-11 09:27, Marc Chamberlin wrote:
Thanks Andrei for trying to help but I guess I am somewhat confused. (And I will admit I don't fully grok the documentation on Grub2 and Yast)
I don't think the issue is that BIOS is not allowing booting from my new drive, it can and I did manage to get it to do so. The problem is that the BIOS setup GUI is designed to only show up to 3 drives in the menu where one can configure the order to search them. My new drive did not initially show up as one of the possible drives to search for a boot loader, but when I disconnected one of the other drives, then my new drive did show up in that list, and I was able to move it to the first drive to search, at which point it did indeed boot up. (I could tell that it was booting up off my new drive because it presented the fancy new boot menu interface that came with Leap 42.1) But when I reconnected the drive that I had disconnected, I lost the ability to boot off the new drive and the system when back to booting up from one of the other drives. Moving SATA cables around to different ports did not make a difference in this behavior either, sigh. IMHO this is a rather poor design of the BIOS UI and apparently I have no control over which set of drives it is going to select to present for configuring the search order.
Ok, so that "invisible" disk has now the system installed properly and it boots when it is visible. One reason for a disk to be invisible might be that it has the same ID as another disk :-? fdisk -l /dev/sdb ... Disk label type: dos Disk identifier: 0x00... <=== Just a wild guess. This can happen when cloning a disk. fdisk can change that ID.
I think your second comment was the jist of my original question. How do I get YaST to allow me to select a drive to install an MBR bootloader on? It seems to want to only install it on the same drive that I installed the operating system on that YaST is running under.
If I understand your third statement, (and I admit I am on unsure footing here) I think you are saying that I should create a partition on one of the drives that the BIOS is seeing when I have all four drives connected? And then mount this partition at /boot ? I have thought about doing that, but it seems fraught with other issues so I have not done this. What file system do I choose for this partition?
ext2
What size should it be?
500 MB.
Is this partition to be mounted at /boot for all the different OS's that I want to boot up?
Only for one.
And don't I still have the problem of getting an MBR written out onto a drive that the BIOS is willing to work with?
No, because you are writing to another disk that is one of the three that are visible.
To phrase that last question a different way, does YaST install the MBR on the drive that / is located on, or does YaST install the MBR on the drive that /boot is located on? Or is there some other model being used that I don't grok?
Where boot is located.
If I understand the boot loader model correctly, then I believe the MBR exists outside of partitions and is just located on the first section of a drive. This means each drive can have an MBR. And the MBR contains bootloader code and a pointer to a partition/file system where a GRUB bootloader (or some other OS bootloader) is stored.
Yes.
And the GRUB bootloader brings up a menu via which a user can use to select an actual OS to load.
Yes There is another method, one that I'm using (with help). You install a small Linux in the disk that the computer wants to boot, complete with its own grub. A single partition. Minimal X install. Or text only if you are happy with it. Less than 10 GB suffices, maybe 6. It can also be used as rescue system on emergencies. This Grub is prepared to boot other grub setups on other disks. The second grub does not use the disk mbr, it is installed on the root filesystem of that install. -- Cheers / Saludos, Carlos E. R. (from 13.1 x86_64 "Bottle" at Telcontar)