Symantec Veritas Cluster Server One, Installation Manual

Page: 159 / 210

159 Troubleshooting
Troubleshooting I/O fencing
Nodes A and B
and private
networks lose
power.
Coordinator and
data disks retain
power.
Power returns to
systems and they
reboot, but
private networks
still have no
power.
Reboots and I/O fencing driver
(vxfen) detects Node B is
registered with coordinator
disks. Because the private
networks are down, the driver
does not see Node B listed as
member of the VCS One cluster.
This causes the I/O fencing
device driver to prevent Node A
from joining the VCS One
cluster. Node A console displays
the following:
Potentially a
preexisting split brain.
Dropping out of the
cluster. Refer to the
user documentation for
steps required to clear
preexisting split brain.
Reboots and I/O fencing driver
(vxfen) detects Node A is
registered with coordinator
disks. Because the private
networks are down, the driver
does not see Node A listed as
member of the VCS One cluster.
This causes the I/O fencing
device driver to prevent Node B
from joining the VCS One
cluster. Node B console displays
the following:
Potentially a
preexisting split
brain. Dropping out of
the cluster. Refer to
the user documentation
for steps required to
clear preexisting split
brain.
For instructions on
resolving preexisting split
brain condition, see
“ Troubleshooting I/O
fencing ” on page 152.
Node A crashes
while Node B is
down. Node B
comes up and
Node A is still
down.
Crashes. Reboots and detects Node A is
registered with the coordinator
disks. The driver does not see
Node A listed as member of the
VCS One cluster. The I/O
fencing device driver prints the
following message on console:
Potentially a
preexisting split
brain. Dropping out of
the cluster. Refer to
the user documentation
for steps required to
clear preexisting split
brain.
See “ Installing Storage
Foundation after installing
the client on Linux ” on
page 151 for instructions
on resolving preexisting
split brain condition.
Table C-1 I/O fencing scenarios
Event Node A activity Node B activity Operator action