[gpfsug-discuss] help with multi-cluster setup: Network is unreachable

[Jaime Pinto]

We have a setup in which "cluster 0" is made up of clients only on  
gpfs v3.5, ie, no NDS's or formal storage on this primary membership.

All storage for those clients come in a multi-cluster fashion, from  
clusters 1 (3.5.0-23), 2 (3.5.0-11) and 3 (4.1.1-7).

We recently added a new storage cluster 4 (4.1.1-14), and for some  
obscure reason we keep getting "Network is unreachable" during mount  
by clients, even though there were no issues or errors with the  
multi-cluster setup, ie, 'mmremotecluster add' and 'mmremotefs add'  
worked fine, and all clients have an entry in /etc/fstab for the file  
system associated with the new cluster 4. The weird thing is that we  
can mount cluster 3 fine (also 4.1).

Another piece og information is that as far as GPFS goes all clusters  
are configured to communicate exclusively over Infiniband, each on a  
different 10.20.x.x network, but broadcast 10.20.255.255. As far as  
the IB network goes there are no problems routing/pinging around all  
the clusters. So this must be internal to GPFS.

None of the clusters have the subnet parameter set explicitly at  
configuration, and on reading the 3.5 and 4.1 manuals it doesn't seem  
we need to. All have cipherList AUTHONLY. One difference is that  
cluster 4 has DMAPI enabled (don't think it matters).

Below is an excerpt of the /var/mmfs/gen/mmfslog in one of the clients  
during mount (10.20.179.1 is one of the NDS on cluster 4):
Mon May  8 11:35:27.773 2017: [I] Waiting to join remote cluster  
wosgpfs.wos-gateway01-ib0
Mon May  8 11:35:28.777 2017: [W] The TLS handshake with node  
10.20.179.1 failed with error 447 (client side).
Mon May  8 11:35:28.781 2017: [E] Failed to join remote cluster  
wosgpfs.wos-gateway01-ib0
Mon May  8 11:35:28.782 2017: [W] Command: err 719: mount  
wosgpfs.wos-gateway01-ib0:wosgpfs
Mon May  8 11:35:28.783 2017: Network is unreachable


I see this reference to "TLS handshake" and error 447, however  
according to the manual this TLS is only set to be default on 4.2  
onwards, not 4.1.1-14 that we have now, where it's supposed to be EMPTY.

mmdiag --network for some of the client gives this excerpt (broken status):
     tapenode-ib0                        <c4p1>   10.20.83.5       
broken     233  -1    0         0          Linux/L
     gpc-f114n014-ib0                    <c4p2>   10.20.114.14     
broken     233  -1    0         0          Linux/L
     gpc-f114n015-ib0                    <c4p3>   10.20.114.15     
broken     233  -1    0         0          Linux/L
     gpc-f114n016-ib0                    <c4p4>   10.20.114.16     
broken     233  -1    0         0          Linux/L
     wos-gateway01-ib0                   <c4p5>   10.20.179.1      
broken     233  -1    0         0          Linux/L



I guess I just need a hint on how to troubleshoot this situation (the  
4.1 troubleshoot guide is not helping).

Thanks
Jaime



---
Jaime Pinto
SciNet HPC Consortium - Compute/Calcul Canada
www.scinet.utoronto.ca - www.computecanada.ca
University of Toronto
661 University Ave. (MaRS), Suite 1140
Toronto, ON, M5G1M1
P: 416-978-2755
C: 416-505-1477

----------------------------------------------------------------
This message was sent using IMP at SciNet Consortium, University of Toronto.