Hard drive weirdness.

[David Gibb]

In case it wasn't obvious, what would really be awesome is if the
first sata drive _always_ pointed to /dev/sda, the second sata drive
_always_ pointed to /dev/sdb, and the pata drive _always_ pointed to
/dev/sdc. That way, the software raid (and I!) wouldn't get so
confused. In addition, if mdadm tells me that /dev/sda failed, for
example, I'd actually know what that meant. Is that possible?

David

On Wed, Jul 23, 2008 at 1:14 PM, David Gibb <degibb at gmail.com> wrote:
> Things are getting better! But I'm not quite there yet...
>
> I did:
>
> device (hd0) /dev/sdc
> root (hd0,0)
> setup (hd0)
> quit
>
> And I rebooted. I changed my bios settings to boot from 'IDE-0', and
> then I got a grub Error 17:  Cannot mount selected partition...
>
> Oops. Forget to change the menu.lst. I changed root from (hd2,0) to
> (hd0,0), rebooted, and it worked ok. The root (pata) drive is at
> /dev/sdc. Great!
>
> Now I tried removing both sata drives. It boots ok, but I noticed that
> the the root drive is now set to /dev/sda.
>
> When I remove a sata drive, root is set to /dev/sdb, and mdadm
> --detail /dev/md0 tells me that the md device does not appear to be
> active. I'm just guessing here, but could this be because it's
> confused by the fact that one of the raid drives (sdb) is already
> mounted as root?
>
> Anyway, I think you see where I'm going here. My problem is that raid
> expects the drives to be /dev/sda and /dev/sdb, but that's only the
> case when all three drives are running. When a drive goes missing, the
> 'space' in the lettering is filled by the pata drive, and my raid
> device gets all confused.
>
> Thanks again for all your help,
> David
>
> On Wed, Jul 23, 2008 at 12:26 PM, Rashkae <ubuntu at tigershaunt.com> wrote:
>> David Vincent wrote:
>>
>>>
>>> 2.  in ubuntu install "gparted" in your favorite manner either with
>>> synaptic or the add/remove programs app or apt-get or whatever.  open
>>> gparted (found under the System menu in Administration) and locate your
>>> /dev/sdb drive.  right-click the partition and see what flags are set on
>>> it.  click the "boot" flag if it isn't ticked.  click "ok"
>>>
>>
>> This step is... useless. Won't hurt anything, but doesn't achieve
>> anything.  It doesn't matter to grub which partition is or is not marked
>> bootable.. Unless you are doing something exotic by mixing MS-DOS chain
>> loader MTBR with grub, marking partitions as bootable has no effect.
>> You would need to setup grub on each device for grub to boot from either
>> hard drive.  However, since in this case, the /boot resides outside the
>> raid, you can't boot if the root drive is dead anyhow, so there is no
>> point in making the raid members bootable.
>>
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>