[Beowulf] Cannot use more than two nodes on cluster

Antti Korhonen akorhonen at theranos.com
Wed Sep 19 23:40:56 PDT 2012

Passwordless SSH works between all nodes.
Firewalls are disabled.

From: greg at r-hpc.com [mailto:greg at r-hpc.com] On Behalf Of Greg Keller
Sent: Wednesday, September 19, 2012 8:43 PM
To: beowulf at beowulf.org; Antti Korhonen
Subject: Re: [Beowulf] Cannot use more than two nodes on cluster

I am going to bet $0.25 that SSH or TCP/IP is configured to allow the master to get to the nodes without a password, but not from one Compute to the other Compute.

Test by sshing to Compute1, then from Compute1 to Compute2.  Depending on how you built the cluster, it's also possible there is iptables running on the compute nodes but, my money is on the ssh keys need reconfiguring.  Let us know what you find.


Date: Wed, 19 Sep 2012 16:11:21 +0000
From: Antti Korhonen <akorhonen at theranos.com<mailto:akorhonen at theranos.com>>
Subject: [Beowulf] Cannot use more than two nodes on cluster
To: "beowulf at beowulf.org<mailto:beowulf at beowulf.org>" <beowulf at beowulf.org<mailto:beowulf at beowulf.org>>
        <B9D51F953BEE5C42BC2B503D288542992DD935FE at SRW004PA.theranos.local<mailto:B9D51F953BEE5C42BC2B503D288542992DD935FE at SRW004PA.theranos.local>>
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I have a small Beowulf cluster (master and 3 slaves).
I can run jobs on any single nodes.
Running on two nodes sort of works, running jobs on master and 1 slave works.
(all combos, master+slave1 or master+slave2 or master+slave3)
Running jobs on two slaves hangs.
Running jobs on master + any two slaves hangs.

Would anybody have any troubleshooting tips?

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