How to change the preferred minor

How to change the preferred minor

[Anders Nielsen]

When I try to boot my box with disks which previously was configured in
other machines md tries to autodetect which array should have a given
minor number.

I use the wonderful :-) mdadm -E and I can see a preferred minor value
which is very nice, but since more than one array is competing for the
same minor number it is kind of difficult for me to figure out what to
put in my /etc/fstab.

Therefore my question is: how do I change the preferred minor value on a
array so I can prevent conflicts? I would of course like to be able to
use mdadm for this job :-)

Thanks,
  Anders Nielsen

Re: How to change the preferred minor

[Anders Nielsen]

tor, 2002-04-11 kl. 02:56 skrev Neil Brown:
> On  April 10, anielsen@diku.dk wrote:
> > When I try to boot my box with disks which previously was configured in
> > other machines md tries to autodetect which array should have a given
> > minor number.
> > 
> > I use the wonderful :-) mdadm -E and I can see a preferred minor value
> > which is very nice, but since more than one array is competing for the
> > same minor number it is kind of difficult for me to figure out what to
> > put in my /etc/fstab.
> > 
> > Therefore my question is: how do I change the preferred minor value on a
> > array so I can prevent conflicts? I would of course like to be able to
> > use mdadm for this job :-)
> 
> This would be one of the reasons that I neither use nor recommend RAID
> autostart.  It is too dependant on the preferred-minor which is hard
> to change.
> I guess I could add an option to mdadm to change the preferred-minor
> as it could be useful, but I'm not highly motivated.  Maybe a
> --rewrite-superblock option to --assemble...
> 
> I recommend that you enumerate the uuids of your arrays, create
> /etc/mdadm.conf to say which uuid matches which /dev/md? and use 
>  mdadm --assemble --scan
> to assemble your arrays.
> 
> NeilBrown


I see that the method you recommend is more flexible since there are
more uuids than minor numbers :-)

But I am not sure how I disable autostart and replace it with mdadm -A
--scan so I could use some help.

I am using Redhat 7.2. I guess I have to change an initscript or
something.

Thanks,
 Anders