Theoretically, this is a straightforward task but in reality CloudMan
gets in the way of making it stick. Namely, if you are to manually
remove the master instance from being an execution host, CloudMan will
add it back in the next time a node is added or removed from the
cluster, thus negating your manual modification.
So, I will add this feature to CloudMan itself but I cannot commit to
a date right now. It should be soon though.
In the mean time, if you'd like to script this yourself via an add-hoc
solution that runs periodically, below is the procedure for manually
removing a node from SGE's execution host list:
ubuntu@ip-10-204-170-63:~$ sudo -s
HOSTNAME ARCH NCPU LOAD MEMTOT MEMUSE
global - - - - -
ip-10-204-170-63 lx24-amd64 1 1.11 615.2M 161.6M
# Remove the host from the list of execution hosts
root@ip-10-204-170-63:~# qconf -de ip-10-204-170-63
Host object "ip-10-204-170-63" is still referenced in cluster queue
# Edit the configuration of allhosts and remove the host in question.
If this is the only host in the list, replace it's name with word NONE
root@ip-10-204-170-63:~# qconf -mhgrp "@allhosts"
email@example.com modified "@allhosts" in host group
# Show configuraiton of group allhosts
root@ip-10-204-170-63:~# qconf -shgrp "@allhosts"
# The hos is now removed from the list of execution hosts
root@ip-10-204-170-63:~# qstat -f