[gpfsug-discuss] Odd behavior using sudo for mmchconfig

[Peter Childs]

Yesterday, I updated updated some gpfs config using 

sudo /usr/lpp/mmfs/bin/mmchconfig -N frontend
maxFilesToCache=200000,maxStatCache=800000

which looked to have worked fine, however later other machines started
reported issues with permissions while running mmlsquota as a user, 

cannot open file `/var/mmfs/gen/mmfs.cfg.ls' for reading (Permission
denied)
cannot open file `/var/mmfs/gen/mmfs.cfg' for reading (Permission
denied)


this was corrected by run-running the command from the same machine
within a root session.

sudo -s
/usr/lpp/mmfs/bin/mmchconfig -N frontend
maxFilesToCache=20000,maxStatCache=80000
/usr/lpp/mmfs/bin/mmchconfig -N frontend
maxFilesToCache=200000,maxStatCache=800000
exit

I suspecting an environment issue from within sudo caused the gpfs
config to have its permissions to change, but I've done simular before
with no bad effects, so I'm a little confused.

We're looking at tightening up our security to reduce the need for need
for root based password less access from none admin nodes, but I've
never understood the expect requirements this is using setting
correctly, and I periodically see issues with our root known_hosts
files when we update our admin hosts and hence I often endup going
around with 'mmdsh -N all echo ""' to clear the old entries, but I
always find this less than ideal, and hence would prefer a better
solution.

Thanks for any ideas to get this right and avoid future issues.

I'm more than happy to open a IBM ticket on this issue, but I feel
community feed back might get me further to start with.

Thanks

-- 
Peter Childs
ITS Research Storage
Queen Mary, University of London