master/slave brokers both become unresponsive with nfs-side HA failover

Logs
=========

The logs show that both brokers receive an error at 16:04:24:

Master
-----------
//NOTE: logs only go back to 16:00
$ egrep -r "Shutting|Starting|ERROR|WARN" amq01-logs | egrep -v "AMQ222061|AMQ224016|AMQ222107|AMQ212037" 

amq01-logs/artemis.log.2:2020-12-21 16:04:25,224 WARN [org.apache.activemq.artemis.core.server] AMQ222010: Critical IO Error, shutting down the server. file=NULL, message=IO Error while calculating disk usage: java.nio.file.FileSystemException: /amqdata/amq7_broker_data/paging: Input/output error


Slave
-----------
$ egrep -r "Shutting|Starting|ERROR|WARN" amq02-logs | egrep -v "AMQ222061|AMQ224016|AMQ222107|AMQ212037"

amq02-logs/artemis.log.5:2020-12-21 16:04:24,092 WARN [org.apache.activemq.artemis.core.server.impl.FileLockNodeManager] Failure when accessing a lock file: java.io.IOException: Input/output error


Thread Dumps
===============

The thread dumps, captured about 15 mins later, indicate the following:

Master
----------

"Thread-5 (ActiveMQ-server-org.apache.activemq.artemis.core.server.impl.ActiveMQServerImpl$6@46074492)"
#34 prio=5 os_prio=0 cpu=265.58ms elapsed=774.83s tid=0x00007f476d086800 nid=0x17cb waiting on condition [0x00007f470fbf9000]
   java.lang.Thread.State: TIMED_WAITING (parking)
at jdk.internal.misc.Unsafe.park(java.base@11.0.7/Native Method)
- parking to wait for  <0x000000009dece8c8> (a java.util.concurrent.CountDownLatch$Sync)
at java.util.concurrent.locks.LockSupport.parkNanos(java.base@11.0.7/LockSupport.java:234)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedNanos(java.base@11.0.7/AbstractQueuedSynchronizer.java:1079)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireSharedNanos(java.base@11.0.7/AbstractQueuedSynchronizer.java:1369)
at java.util.concurrent.CountDownLatch.await(java.base@11.0.7/CountDownLatch.java:278)
at org.apache.activemq.artemis.core.journal.impl.SimpleWaitIOCallback.waitCompletion(SimpleWaitIOCallback.java:61)
at org.apache.activemq.artemis.core.journal.impl.JournalBase.appendCommitRecord(JournalBase.java:63)
at org.apache.activemq.artemis.core.journal.impl.JournalImpl.appendCommitRecord(JournalImpl.java:91)
at org.apache.activemq.artemis.core.persistence.impl.journal.AbstractJournalStorageManager.commitBindings(AbstractJournalStorageManager.java:658)
...
"Thread-10" #106 prio=5 os_prio=0 cpu=355.87ms elapsed=547.38s tid=0x00007f4734002000 nid=0x1bc0 waiting for monitor entry [0x00007f47033e3000]
   java.lang.Thread.State: BLOCKED (on object monitor) at org.apache.activemq.artemis.core.postoffice.impl.PostOfficeImpl.stop(PostOfficeImpl.java:198)
- waiting to lock <0x000000008069d340> (a org.apache.activemq.artemis.core.postoffice.impl.PostOfficeImpl)
at org.apache.activemq.artemis.core.server.impl.ActiveMQServerImpl.stopComponent(ActiveMQServerImpl.java:1356)
at org.apache.activemq.artemis.core.server.impl.ActiveMQServerImpl.stop(ActiveMQServerImpl.java:1170)
at org.apache.activemq.artemis.core.server.impl.ActiveMQServerImpl.stop(ActiveMQServerImpl.java:1051)
at org.apache.activemq.artemis.core.server.impl.ActiveMQServerImpl$5.run(ActiveMQServerImpl.java:857)
   Locked ownable synchronizers:
- None

Slave
----------

"AMQ229000: Activation for server ActiveMQServerImpl::serverUUID=ee4ebeb8-2391-11eb-9967-0021f64befb7"
#15 prio=5 os_prio=0 cpu=317.50ms elapsed=685.73s tid=0x00007f39c8f48000 nid=0x4deb waiting on condition [0x00007f399cae5000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
        at java.lang.Thread.sleep(java.base@11.0.6/Native Method)
        at org.apache.activemq.artemis.core.server.impl.FileLockNodeManager.awaitLiveNode(FileLockNodeManager.java:183)
        at org.apache.activemq.artemis.core.server.impl.SharedStoreBackupActivation.run(SharedStoreBackupActivation.java:77)
        at org.apache.activemq.artemis.core.server.impl.ActiveMQServerImpl$ActivationThread.run(ActiveMQServerImpl.java:3730)

   Locked ownable synchronizers:
        - None