Difference between revisions of "FAQ"
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| − | How to open socket from CN to outside world | + | ==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 (<tt>192.168.1.</tt>''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. | |
| − | How to find | + | To enable the translation, pass <tt>ZOID_NAT_ENABLE</tt> environment variable when submitting a job. An administrator can also enable this option permanently in the [[ZOID#opt_enable_nat|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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[[KTAU]] | [[ZeptoOS_Documentation|Top]] | [[KTAU]] | [[ZeptoOS_Documentation|Top]] | ||
Revision as of 14:32, 28 April 2009
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)
