Due to an issue on iris, the X11 forwarding option is not working:

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$> ssh -Y iris-cluster
(access)$> si --x11
svarrette@iris-001(iris-cluster) ~(81548 1N/1T/1CN)> xterm     # FAILED
xterm: Xt error: Can't open display: localhost:69.0

Here is a workaround for this issue (thanks to X. Besseron):

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$> # Connect to iris using the X11 forwarding
$> ssh -Y iris-cluster
(access)$> # Reserve an node interactively
(access)$> salloc -p interactive --qos debug bash -c 'ssh -Y $(scontrol show hostnames | head -n 1)'
[cparisot@iris-018 ~]$ xterm # It work's !

Here are some explanation of what the command do:

• Request node allocation in interactive partition with debug
• When the resource is allocated, spawn a bash process that will run a command
• The command permits to connect to the first node of the reservation directly by using ssh with forwarding enable (‘-Y’ option)
• You can give extra options at salloc (before the ‘bash -c’ command) like the number of cores.