Lustre discuss - Oct 2014 - servicenode/failnode and comma separated values

All,

I notice there seems to be a difference between putting all your nids as comma
separated values for servicenode/failnode and putting them as separate entries
for each one.

Here is an output of a dryrun against an OST that was created using multiple
"--servicenode=" options. I ran tune2fs with the same nids, but as
comma separated on a single "--servicenode" option:

============================snip=========================#tunefs.lustre 
--dryrun
--servicenode=10.100.1.10@o2ib,10.100.1.11@o2ib,10.100.1.12@o2ib,10.100.1.13@o2ib,10.100.1.14@o2ib,10.100.1.15@o2ib
--verbose /dev/VG_Hamming/WORK_OST17checking for existing Lustre data: found
Reading CONFIGS/mountdata

   Read previous values:
Target:     WORK-OST0011
Index:      17
Lustre FS:  WORK
Mount type: ldiskfs
Flags:      0x1062
              (OST first_time update no_primnode )
Persistent mount opts: errors=remount-ro
Parameters: mgsnode=10.100.1.11@o2ib:10.100.1.10@o2ib
failover.node=10.100.1.10@o2ib failover.node=10.100.1.11@o2ib
failover.node=10.100.1.12@o2ib failover.node=10.100.1.13@o2ib
failover.node=10.100.1.14@o2ib failover.node=10.100.1.15@o2ib


   Permanent disk data:
Target:     WORK:OST0011
Index:      17
Lustre FS:  WORK
Mount type: ldiskfs
Flags:      0x1062
              (OST first_time update no_primnode )
Persistent mount opts: errors=remount-ro
Parameters: mgsnode=10.100.1.11@o2ib:10.100.1.10@o2ib
failover.node=10.100.1.10@o2ib failover.node=10.100.1.11@o2ib
failover.node=10.100.1.12@o2ib failover.node=10.100.1.13@o2ib
failover.node=10.100.1.14@o2ib failover.node=10.100.1.15@o2ib
failover.node=10.100.1.10@o2ib,10.100.1.11@o2ib,10.100.1.12@o2ib,10.100.1.13@o2ib,10.100.1.14@o2ib,10.100.1.15@o2ib

exiting before disk write.
============================snip=========================
So is there a difference in how lustre will use those failover.node settings? If
so, what is it and if not, shouldn't there be some consistency in how that
is stored/displayed?


Brian Andrus
ITACS/Research Computing
Naval Postgraduate School
Monterey, California
voice: 831-656-6238