[gpfsug-discuss] Multi-cluster question (was Re: gpfsug-discuss Digest, Vol 100, Issue 32)

[Jonathan Buzzard]

On 29/05/2020 20:55, Stephen Ulmer wrote:
> I have a question about multi-cluster, but it is related to this thread 
> (it would be solving the same problem).
> 
> Let’s say we have two clusters A and B, both clusters are normally 
> shared-everything with no NSD servers defined.

Er, even in a shared-everything all nodes fibre channel attached you 
still have to define NSD servers. That is a given NSD has a server (or 
ideally a list of servers) that arbitrate the disk. Unless it has 
changed since 3.x days. Never run a 4.x or later with all the disks SAN 
attached on all the nodes.

> We want cluster B to be 
> able to use a file system in cluster A.  If I zone the SAN such that 
> cluster B can see all of cluster A’s disks, can I then define a 
> multi-cluster relationship between them and mount a file system from A on B?
> 
> To state it another way, must B's I/O for the foreign file system pass 
> though NSD servers in A, or can B’s nodes discover that they have 
> FibreChannel paths to those disks and use them?
> 

My understanding is that remote cluster mounts have to pass through the 
NSD servers.


JAB.

-- 
Jonathan A. Buzzard                         Tel: +44141-5483420
HPC System Administrator, ARCHIE-WeSt.
University of Strathclyde, John Anderson Building, Glasgow. G4 0NG