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https://issues.apache.org/jira/browse/AMQ-5549?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14298738#comment-14298738
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Torsten Mielke commented on AMQ-5549:
-------------------------------------

{quote}
Maybe I wasn't clear enough in the original issue description but this is about 
NFS server failures (crash, network outage, ungraceful shutdown, ...) affecting 
all the NFS clients.
{quote}
Got you. Have not tested that. With restartAllowed=false the master should shut 
down at the least and stop its transport connectors.

Also did some more reading on sync mount option. It is discouraged in some 
posts but I would hope that by also using noac or sync mount option, it should 
be okay as writes are sync now. So data should not get corrupted. This however 
comes at the expense of a performance degradation.




> Shared Filesystem Master/Slave using NFSv4 allows both brokers become active 
> at the same time
> ---------------------------------------------------------------------------------------------
>
>                 Key: AMQ-5549
>                 URL: https://issues.apache.org/jira/browse/AMQ-5549
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker, Message Store
>    Affects Versions: 5.10.1
>         Environment: - CentOS Linux 6
> - OpenJDK 1.7
> - ActiveMQ 5.10.1
>            Reporter: Heikki Manninen
>            Priority: Critical
>
> Identical ActiveMQ master and slave brokers are installed on CentOS Linux 6 
> virtual machines. There is a third virtual machine (also CentOS 6) providing 
> an NFSv4 share for the brokers KahaDB.
> Both brokers are started and the master broker acquires file lock on the lock 
> file and the slave broker sits in a loop and waits for a lock as expected. 
> Also changing brokers work as expected.
> Once the network connection of the NFS server is disconnected both master and 
> slave NFS mounts block and slave broker stops logging file lock re-tries. 
> After a short while after bringing the network connection back the mounts 
> come back and the slave broker is able to acquire the lock simultaneously. 
> Both brokers accept client connections.
> In this situation it is also possible to stop and start both individual 
> brokers many times and they are always able to acquire the lock even if the 
> other one is already running. Only after stopping both brokers and starting 
> them again is the situation back to normal.
> * NFS server:
> ** CentOS Linux 6
> ** NFS v4 export options: rw,sync
> ** NFS v4 grace time 45 seconds
> ** NFS v4 lease time 10 seconds
> * NFS client:
> ** CentOS Linux 6
> ** NFS mount options: nfsvers=4,proto=tcp,hard,wsize=65536,rsize=65536
> * ActiveMQ configuration (otherwise default):
> {code:xml}
>         <persistenceAdapter>
>             <kahaDB directory="${activemq.data}/kahadb">
>               <locker>
>                 <shared-file-locker lockAcquireSleepInterval="1000"/>
>               </locker>
>             </kahaDB>
>         </persistenceAdapter>
> {code}



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