HP Z800 or HP xw8600: How to set which disk to boot in bios

[hput3]

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@DGroves wrote:

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most bios's will allow  selecting the "found" disk(s) search order to place the desired boot disk as the "First One"

if you have a board multiple mass storage controllers (like the z800) you need to disable the bios of one controller, usually the "LSI" one but some people do the opposite turning off the z800 SATA controller

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Before posting I had laboriously removed one disk at a time until it booted.  I've had trouble getting to what seems to be the problem disk   With problem disc connected, my usb rescue disk ("Systemrescue") plugged into USB,  and using F9 to set boot device to the USB. When machine  gets to boot part it starts to use usb but then jumps to problem disk (What follows is all linux stuff since that is the OS) and ends up at "grub rescue" prompt.  allegedly you can run `ls' and see what the bios is seeing.  In this case (hd0), (hd0,dos5), (hd1), (hd2).  Supposedly you can identify the `root' installation by running 'ls' on each one... and taking certain steps from there.

In my case 'ls' shows nothing at any of them.  I think I might no why.

Note: `grub is the most common bootloader in linux'

What I think has happened is that during a couple of misfire installs  I managed to get a disk partitioned and grub installed into the MBR space,  but nothing more.  So  grub  is installed in (hd0) . .  Hence bios is seeing it in a similar way as it sees the MBR running windows.

So the short and long of it is; I have two discs that appear to be bootable discs.  One actually is a fully prepared Linux boot disc.  The other is not 

I've tried several times to get booted on a usb or cdrom recue disk to use gparted on the partially formatted disk and clean it up down to no partitions and only gpt.  In that condition I'm pretty sure it will quit attracting the bios attention but will still be thoroughly usable by the zfs file system.  (I've made a zfs zpool from such a disc before)

It seems at this point, I cannot get to the 'bad' disc with repair tools.   I've at least gotten the disc identified.

I do have LSI on board and not in use.   Do you think; given what I discussed above that disabling LSI bios will still have an effect?

I'm going to try that in the next hour or so .... as always many thanks for the experienced help.

[DGroves]

your going to have to remove the GRUB bootloader from one disk, (in your case the disk that does not have a full install) and then reinstall the os(s) on that disk

https://www.wikihow.com/Bypass-Grub-Rescue-on-a-Linux-Computer

[hput3]

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@DGroves wrote:

your going to have to remove the GRUB bootloader from one disk, (in your case the disk that does not have a full install) and then reinstall the os(s) on that disk

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Er... thats what I was saying last post.

Although no reinstall is necessary... I just got the clinker cleaned up and put it to work, clearing the way to a configured and loaded OS already waiting in the wings.

Since the problem was on an SAS disk, I'm thinking LSI was attempting to use it.

But a certain party whos' name I can't say outloud, but I will say his initials DGROVES.   Gave me instructions to to disable LSI.

When a few chores done... I did that and my booting troubles disappeared.  First move was to reduce the "bad? disk to a state of no partitions and only giving it the gpt.  I know for certain that is all it needs since I have already created a zpool out of it and have started putting files on it.

zfs is like that, you can just about throw any old thing at it and it will just quietly make it usable and go to work.

Thank you Mister DGroves.  once more.