FAQ

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How to open a socket from a CN to the outside world

ZOID provides IP packet forwarding between the compute nodes and the I/O nodes. However, because the compute nodes use non-routable IP addresses (192.168.1.x), they cannot communicate directly with the outside world.

The most transparent solution to this problem is to perform network address translation (NAT) on the I/O nodes using the Linux kernel netfilter infrastructure. We used to enable this by default, but experiments have shown it to have a detrimental effect on the overall performance of the TCP/IP stack on the I/O nodes, slowing down access to the network filesystems.

To enable the translation, pass ZOID_NAT_ENABLE environment variable when submitting a job. An administrator can also enable this option permanently in the config file.

How to obtain a CN node number

(some info on /proc/personality.sh)

How to obtain a Cobalt job ID

on CN and ION (user script)

How to find the MPI rank from a shell script


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