what does 3par cluster master means ?

[bayern0906]

Hi,

I'm new to 3par arrays. Someone knows what a cluster master node (not the network master) means?

As far as I know, LUNs on a 3par system has an ownership and I assume 3par is an asymmetric active/active system that each node in a node pair is doing its own job unless one fails and the other one take over the job of the failed one. So what does master node means in normal status ?

Thx.

[Prakash Singh_1]

Hello,

You can refer the link below for complete 3PAR CLX solution details -

https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-a00009594en_us

[bayern0906]

Thanks for your reply.

However I want to know what a master node(shown by command "showsys") does in a 2-node system.

[Dennis Handly · Accepted solution]

Basically there are demons running on specific nodes.  sysmgr is one that can only be active on the master node.

If that node goes down, the demons are started on another node.

The Concepts Guide may explain this better.

> LUNs on a 3par system has an ownership

No, VLUNs and VVs don't have an ownership.  Only LDs and PDs.

> I assume 3PAR is an asymmetric active/active system that each node in a node pair is doing its own job unless one fails

No, each node does its job all the time.  It is only the management that is restricted to a node.

[bayern0906]

Hi Dennis

Thank you for your reply. It really helps me a lot and I have few more questions.

So LUNs do not have ownership and both nodes in a cluster (In my environment, 2-node) can handle IO to the same LUN at the same time ? Then I think there's a LUN lock mechanism ?

Besides, if one of the nodes failed,  how the remaining node knows that the partner node had failed ? Is there a quorum inside the controllers chassis ?

[Dennis Handly]

> Then I think there's a LUN lock mechanism?

To protect what?

> how the remaining node knows that the partner node had failed?

As Sheldon mentioned here, the nodes are connected:

https://community.hpe.com/t5/3PAR-StoreServ-Storage/how-3par-performs-node-failover-in-a-2-node-system/m-p/6996346