Dual paths, pvcreate/vgcreate, alternate links

[Ron Levy]

I have a VA7410, and two rp5470 machines each with two fibre channel cards so they each have two paths to the VA7410.
Foolishly, I created volume groups and shared them and I did not use pvcreate for physical volume groups. Now, when I try to add the alternate link, it adds it as a volume, not as an alternate link, and I have two alternate hardware paths that I know go to the same place accessed twice. (ie, there's a 30GB LUN on the VA7410, I access it twice and the machine thinks I have a 60GB-capable volume group.)

Is there a way to get it to be an alternate link without tearing down my whole shared volume group and redoing it? If I just undistribute it perhaps?

Thanks,
-Ron Levy

[Eugeny Brychkov]

Ron,
please explain more clearly what you did. You can not create LVM volume group w/o using pvcreate, because all other structures are basing on this created by pvcreate. As soon as you did pvcreate and adding physical volume to volume group vgextend reads pv signature and realizes that it's the same disk, but another path and adds path to the link list to pv.
Do you use these LUNs created on VA as raw storage?
Eugeny

[Ron Levy]

I primarily used SAM. So I guess it might have done the pvcreate for me? When it gave me a window about 'configuring into physical volume groups' I left it to default.

[Eugeny Brychkov · Accepted solution]

PVG is PV grouping. Of course, SAM did pvcreate, no doubt.
I think you should check everything once more:
- 'ioscan -fn' to see paths to the same VA LUNs;
- 'vdisplay -v' output for 'pri' and 'alt' device files;
- vgdisplay to see which device file is present, and which is not;
- try to add using vgextend alternate path once more and look to results. If it will not work again, please attach the following outputs here:
- 'ioscan -fn';
- 'vgdisplay -v' for volume group;
- 'pvdisplay -v' for pri and alt PV paths
Eugeny

[Vincente Fernandes]

You need to check the Hardware setup on VA7410. If they are setup problem as primary and alternate on VA7410 then you just need to use "vgextend /dev/vgxx /dev/dsk/cxtxdx(i.e. alternate path).

[Ron Levy]

I checked it all once more and, used a vgextend, and this time it worked perfectly. I then switched the volume group over to the other machine and did the same. I have no idea what I was doing earlier and how it was different, but I suppose it must have been.
Thanks!