Powerpath and pv link querry...

[UnixT]

Hi Gurus,

ia64 hp server rx8640

HP-UX B.11.23

I have a two node cluster where we used a EMC-SYMMETRIX storage. When created LVM on this one node1, we just got it done by adding one of the paths of the disk where 4 redundant are available. On the other node2, we did it by adding all the 4 paths availbale. Now, one of the fc card failed from first node and which path was configured on LVM in that server. But still packages and applications works well on the other node. Here I do have a doubt whether if I switch back the packages to node1 whther it takes the path automatically using powerpath or do we need to add all the available paths to LVM conf ???

[UnixT]

brief of my question is that , in server side do we need to configure all the paths to LVM or system will automatically select the paths as per powerpath ?

[Duncan Edmonstone]

If you are using PowerPath you can just use one path to the disk if you like. Many admins will add all 4 paths anyway as it makes it easier to understand that these are paths to the same set of LUNs.

So no you don't need to do anything with your LVM configurations right now as PowerPath is handling the load-balancing for you, but at some point you should plan to add the other paths in. You can porbably accomplish this with just a vgpexort/vgimport on the non-active node.

HTH

Duncan

[UnixT]

So, adding one path is sufficient enough for a smooth work. Just again a cross confirming

[Duncan Edmonstone]

Yes its sufficient as long as:

powermt display

shows all those disks you have in your VG with active links

HTH

Duncan

[Steve Post]

When Powerpath was installed at my site, EMC told me to only put in one physical volume path, and leave the rest of the paths out. They told me PowerPath needs to handle it, and not PVlinks. This be because PowerPath will be constantly moving the data over the 4 paths for performance.

Now I don't mean to disagree with Duncan. He's basing what he says on experience. I'm just bringing up what EMC told me.

[Robert-Jan Goossens]

Steve,

Could you attach the output of;

# powermt display dev=all

Regards,
Robert-Jan