Software RAID 1 and grub -- was Re: [K12OSN] Linux "Software RAID"

Rob Owens rob.owens at biochemfluidics.com
Fri Aug 8 11:31:18 UTC 2008


I believe you are correct.  With software RAID 1, grub only gets 
installed on one hard drive.  I've read into this a bit, and there are 
fairly straightforward ways of working around it.  For instance, you can 
manually copy the boot sector from one drive to another like this (from 
my "Knoppix Hacks" book):

dd if=/dev/sda of=/dev/sdb bs=446 count=1

Problem is that grub, in most cases, is set to boot from /dev/sda.  If 
/dev/sda goes bad, you have to plug your second hard disk (the good one) 
into the first SATA port so that it will be recognized as /dev/sda.

Another solution I read about was to add additional grub entries telling 
grub to boot from /dev/sdb (do this before copying the boot sector to 
the second drive).  Then if /dev/sda fails, you can interact with grub 
at boot time to tell it to boot "kernel 2.6.xx on /dev/sdb"

Does anybody else have any good suggestions?

-Rob

Onatawahtaw wrote:
> Maybe someone can correct me if I'm wrong, but if you go with software RAID the linux installer will not install grub on all hard drives which can be a problem. I am planning myself to install a RAID 1 so I will have to make sure to install grub on both hard drives. I also heard that it is important not to put swap on RAID. But if you go with hardware RAID is swap still a problem?
> 
> -Kevin
> 
> 
>       
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