[CentOS] Order of sata/sas raid cards

[Jobst Schmalenbach]

I agree with the UUID stuff, I do not like them for the exact same reason.
I do not understand why RedHat cannot include the partition into the UUID,
e.g.

  dev-sda1-c05e-449a-837b-b2579b949d55

As for the first drive, when the kernel boots I think it assigns the
drives in order of the controller on the system bus/slots. As the new controller
sits lower in the slot system (i.e. closer to the CPUs) it is recognised first as
I can see it appearing first in the order being initialized by the kernel.
I cant move it below the old card as there is no slot that has the correct PCI-x8.

I will try the LABEL way of doing ....

I remember that was the same problem a few years back when one had multiple
network interfaces .... until the MAC addresses where introduced into the ifcfg files.

Jobst



On Thu, Aug 23, 2012 at 09:40:24AM -0400, m.roth at 5-cent.us (m.roth at 5-cent.us) wrote:
> Markus Falb wrote:
> > On 23.8.2012 14:01, Jobst Schmalenbach wrote:
> >> Hi Adrian
> >>
> >> yes this will do.
> >> Because I do not know (yet) the UUID of the new partitions (drives),
> >> if I specify the UUID for the known drives for the partitions
> >> the kernel will assign the new drives to higher sdx?
> >> Is this correct?
> >
> > After reboot sdx could be sdy, as you noticed.
> > The solution: you dont access a drive via /dev/sdx
> > You access per UUID and the kernel maps it to the appropiate sdXY which
> > could be sdy after reboot.
> 
> You can also label it. I loathe UUIDs - there is *no* way you're going to
> remember one when you need it. Labels are so much clearer.
> >
> > I am not sure about initial ramdisks etc. maybe there is hardcoded stuff
> > to sdx in there. Maybe it has to be rebuilt? Maybe you has to rebuild
> > initrd as well as updating fstab?
> 
> I've actually never seen a system *not* know what the first drive was,
> hardware-wise. And grub will point to root hd(0,x), normally, not UUID or
> anything else. You *can* (and I do, all the time) use LABEL= on the kernel
> line.
> 
>       mark
> 
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