[CentOS] changing partition priority on install

Phil Schaffner Philip.R.Schaffner at NASA.gov
Wed Oct 29 21:55:19 UTC 2008

Monty Shinn wrote:
> Phil Schaffner wrote:
>> On Tue, 2008-10-28 at 14:59 -0500, Monty Shinn wrote:
>>> Greetings.
>>> I am in the process of installing 5.1 64 bit on a server.  The server 
>>> has 2 3ware cards: 9550SX 12 port, and a 8006 2 port, both SATA.
>> Any reason not to use 5.2?  Will save a lot of updates, and perhaps some
>> headaches.
> <snip>
>> I have vague recollections of having fixed similar problems by tweaking
>> the device ordering in initrd and/or modprobe.conf; however, backing up
>> a step, why do you need to change the order to make things work?  You
>> can install GRUB on the boot device MBR, whatever that may be, and put
>> the OS on the device you want it on without changing the ordering.
>> Phil
> <snip>
> Phil,
> There are a couple of reasons, although they may make no sense.  First, 
> I did not want a multiple point of failure.  If the boot loader is on 
> the MBR of /dev/sda, and the os is on /dev/sdb, then you have a multiple 
> point of failure.  If either card dies, then I am hosed.  It would be 
> *similar* to running a RAID0 on the os.  Not a good idea IMHO.
> Also, if I wanted to replace the "data" drives in the future, I couldn't 
> just unmount the partition and replace the drives.  The boot loader 
> would be gone as well.

A GRUB boot CD (or floppy) will allay the above concerns.  Do an "info 
grub" to find out how to create one.  Can also boot from install media 
to recover a lost GRUB.

> I did not find an option during the install prep to re-locate grub to 
> the MBR of /dev/sdb.  I probably should try the text-based installer to 
> see if there are more options.

It is there in the GUI installer - can't remember exactly where without 
going through the install, but something like an "Advanced" button on a 
configuration page toward the end of the process.

> Heck, I may just remove the 9550 board until the initial os install is 
> completed.  That should accomplish what I am trying to achieve.  Just 
> seems like there should be a more elegant way of doing this.
> I am installing 5.1 because I have the isos on hand.  I was just going 
> to let yum update me to 5.2...

That should work.

> Thanks for your help,



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