Re: switching root fs '/' to boot from RAID1 with grub

[Bill Davidsen <davidsen@tmr.com>]

berk walker wrote:
> H. Peter Anvin wrote:
>> Doug Ledford wrote:
>>>
>>> device /dev/sda (hd0)
>>> root (hd0,0)
>>> install --stage2=/boot/grub/stage2 /boot/grub/stage1 (hd0) 
>>> /boot/grub/e2fs_stage1_5 p /boot/grub/stage2 /boot/grub/menu.lst
>>> device /dev/hdc (hd0)
>>> root (hd0,0)
>>> install --stage2=/boot/grub/stage2 /boot/grub/stage1 (hd0) 
>>> /boot/grub/e2fs_stage1_5 p /boot/grub/stage2 /boot/grub/menu.lst
>>>
>>> That will install grub on the master boot record of hdc and sda, and in
>>> both cases grub will look to whatever drive it is running on for the
>>> files to boot instead of going to a specific drive.
>>>
>>
>> No, it won't... it'll look for the first drive in the system (BIOS 
>> drive 80h).  This means that if the BIOS can see the bad drive, but 
>> it doesn't work, you're still screwed.
>>
>>     -hpa
>> -
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>>
> Depends how "bad" the drive is.  Just to align the thread on this -  
> If the boot sector is bad - the bios on newer boxes will skip to the 
> next one.  But if it is "good", and you boot into garbage - - could be 
> Windows.. does it crash?

Right, if the drive is dead almost every BIOS will fail over, if the 
read gets a CRC or similar most recent BIOS will fail over, but if an 
error-free read returns bad data, how can the BIOS know.

-- 
bill davidsen <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979