The central configuration file for
The cluster configuration is performed throught the cluster element
This section configures the cluster parameters used by eXist during the replica phase. An example of configuration for the cluster environment is shown below:
<cluster
protocol="UDP(mcast_addr=228.1.2.3;mcast_port=7890;ip_ttl=8;ip_mcast=true;
mcast_send_buf_size=800000;mcast_recv_buf_size=150000;
ucast_send_buf_size=800000;ucast_recv_buf_size=150000;
loopback=false):
PING(timeout=2000;num_initial_members=3;up_thread=true;
down_thread=true):
MERGE2(min_interval=10000;max_interval=20000):
FD(shun=true;up_thread=true;down_thread=true;timeout=2500;
max_tries=5):
VERIFY_SUSPECT(timeout=3000;num_msgs=3;up_thread=true;
down_thread=true):
pbcast.NAKACK(gc_lag=50;retransmit_timeout=300,600,1200,2400,4800;
max_xmit_size=8192;up_thread=true;down_thread=true):
UNICAST(timeout=300,600,1200,2400,4800;window_size=100;
min_threshold=10;down_thread=true):
pbcast.STABLE(desired_avg_gossip=20000;up_thread=true;
down_thread=true):
FRAG(frag_size=8192;down_thread=true;up_thread=true):
pbcast.GMS(join_timeout=5000;join_retry_timeout=2000;shun=true;
print_local_addr=true)"
dbaUser="admin" dbaPassword="" exclude="/db/system/temp"
journalDir="/app/exist/journal_1"/>
The protocol attribute rappresents the protocol layers used by JGROUP. For a deep description of the parameters used in this attributes see the jgroup documentation
Interesting parameter are :
The dbaUser and dbaPassword attributes are the account info used by the cluster layer during the replica behaviour. Each actions replicated on cluster environment are performed with this account information.
Some collections should be signed as no-replicated collections i.e. during the replica phase eXist cluster environment doesn't send events based on these collections, colon is the separator char when more than one collection is added.
Specifies the folder where the eXist cluster node saves its journal file.
Directory is automatically created if it doesn't exist
If no journaldir is specifyed, journal is disabled.
For more information on the cluster journal behaviour see Journal cluster behaviour.
Some optional parameters can be added in order to customize the journal behaviour.
Max items that the index file can hold (default = 65000). This value is the maximum number of event that a node can retrieve from master, if the node is disaligned more than this event, a manual realigment must be executed.
Each time the JGroup cluster creates a new coordinator, the new cordinator realign its journal index adding journalIndexShift element to it.
It's created a link to cluster console on sidebar (Cluster status)