Nirvana Enterprise Manager - Realm Configuration

Nirvana Realms can be configured based on a number of parameters that are accessible both through the Nirvana Administration API as well as the Nirvana Enterprise Manager. Any changes made to the configuration parameters for a Nirvana realm are automatically sent to the realm and implemented. This functionality offers major benefits to Administrators, since realms can be configured remotely, without the need to be anywhere near the actual realm itself. More importantly, multiple realms and clustered realms can also be automatically configured remotely.

This section will describe the different configuration parameters that are available using the Nirvana Enterprise Manager.

When you select a realm from the namespace, one of the available panels in the Enterprise Manager is labelled 'Config'. Selecting this panel displays 21 sets of configuration properties, with each set of properties relating to a specific area within the Nirvana Realm. Each set of properties contains different values for specific items. The image below shows the config panel for a selected realm within the namespace.

The 21 configuration groups are :

  • AMQPConfig -
  • Audit Settings - Values relating to what information is stored by the audit process
  • Client Timeout Values - Values relating to client / server interaction
  • Cluster Config - Values specific to the clustering engine
  • Comet Config - Values relating to the configuration of Comet
  • Connection Config - Values relating to the client server connection
  • Data Stream Config - Values relating to the configuration of Data Streams
  • Environment Config - Read only configuration values that relate to the system environment. These cannot be changed.
  • Event Storage - Values specific to how events are stored and retrieved on the server
  • Fanout Values - Values specific to the delivery of events to clients
  • Global Values - Values specific to the realm process itself
  • Inter-Realm Comms Config - Values relating to Inter-Realm communication
  • JVM Management - Values relating to the JVM the Realm Server is using
  • Join Config - Values specific to channel join management
  • Logging Config - Values specific to logging
  • Plugin Config - Values relating to Realm Plugins
  • Protobuf Config - Values relating to Protocol Buffers
  • Proxy Forward Config - Values relating to the configuration of a Proxy Forward
  • RecoveryDaemon - Values relating to clients that are in recovery (i.e. replaying large numbers of events)
  • Thread Pool Config - Values specific to the servers thread pools.
  • TransactionManager - Values specific to the transaction engine of the RealmServer

The table below describes each of the configuration groups and the items that can be changed within each group. It also shows valid ranges of values and a description of what each value actually represents.

Configuration Element Valid Parameters Description
Audit Settings    
ChannelACL True or False Log to the audit file any unsuccessful channel acl interactions. Default is true.
ChannelFailure True or False Log to the audit file any unsuccessful realm interactions. Default is true.
ChannelMaintenance True or False Log to the audit file any channel maintenance activity. Default is false.
ChannelSuccess True or False Log to the audit file any successful channel interactions. Default is false.
InterfaceManagement True or False Log to the audit file any interface management activity. Default is true.
JoinFailure True or False Log to the audit file any unsuccessful join interactions. Default is true.
JoinMaintenance True or False Log to the audit file any join maintenance activity. Default is true.
JoinSuccess True or False Log to the audit file any successful join interactions. Default is false.
QueueACL True or False Log to the audit file any unsuccessful queue acl interactions. Default is true.
QueueFailure True or False Log to the audit file any unsuccessful queue interactions. Default is true.
QueueMaintenance True or False Log to the audit file any queue maintenance activity. Default is false.
QueueSuccess True or False Log to the audit file any successful queue interactions. Default is false.
RealmACL True or False Log to the audit file any unsuccessful realm acl interactions. Default is true.
RealmFailure True or False Log to the audit file any unsuccessful realm interactions. Default is true.
RealmMaintenance True or False Log to the audit file any realm maintenance activity. Default is true.
RealmSuccess True or False Log to the audit file any successful realm interacttions. Default is false.
ServiceACL True or False Log to the audit file any unsuccessful service acl interactions. Default is true.
ServiceFailure True or False Log to the audit file any unsuccessful service interactions. Default is true.
ServiceMaintenance True or False Log to the audit file any service maintenance activity. Default is true.
ServiceSuccess True or False Log to the audit file any successful realm interactions. Default is false.
     
Client Timeout Values    
EventTimeout 5000 to NO_MAX The amount of ms the client will wait for a response from the server. Default is 60000.
HighWaterMark 2 to NO_MAX The high water mark for the connection internal queue. When this value is reached the internal queue is temporarily suspended and unable to send events to the server. This provides flow control between publisher and server. Default is 200.
LowWaterMark 1 to NO_MAX The low water mark for the connection internal queue. When this value is reached the outbound internal queue will again be ready to push event to the server. Default is 50.
QueueAccessWaitLimit 200 to NO_MAX The maximum number of milliseconds it should take to gain access to a queue to push events before notifying listeners. Default is 200
QueueBlockLimit 500 to NO_MAX The maximum number of milliseconds a queue will have reached HWM before notifying listeners, Default is 500.
QueuePushWaitLimit 200 to NO_MAX The maximum number of milliseconds it should take to gain access to a queue and to push events before notifying listeners. Default is 200.
TransactionLifeTime 1000 to NO_MAX The default amount of time a transaction is valid before being removed from the tx store. Default is 20000.
     
Cluster Config    
BufferSize 1400 to 18000 Size in bytes of the inter realm buffer to use
ClientQueueSize 10 to 1000 Size of the client request queue
ClientQueueWindow 10 to 1000 The number of events sent to an async queue reader before the realm will commit
ClientStateDelay 0 to 120000 The number of seconds to delay the cluster processing client requests when a cluster state change occurs
DisableHTTPConnections True or False Disable HTTP(s) connections between cluster nodes
DisconnectWait 1000 to 120000 Time to wait for the node to form in the cluster
DisconnectWhenNotReady True or False If the node has not formed in the cluster then disconnect the client
EnableSites True or False If enabled then the master selection takes into account the Prime Site
EnableStoreRecoveryRetry True or False Enables/Disables the ability for the slave to reattempt a recovery of a store if it detects changes to the store during recovery
EnginePipelineSize 1 to 30 Size of the number of concurrent pipeline threads running within the cluster engine
FastSlaveMode True or False If enabled the realm will move to a slave state while finializing the recovery of local stores
FilterEventsDuringRecovery True or False Only Applicable to JMS Engine Channels. Defines if we recover events that have already been consumed.
FormationTimeout 60000 to 300000 The time to wait for the state to move from recovery to slave or master
HeartBeatInterval 1000 to 120000 Heart Beat interval in milliseconds. Default is 120000.
InitialConnectionTimeout 5000 to 240000 The number of milliseconds that the server will wait while trying to establish a connection to a peer.
IsCommittedDelay 1000 to 30000 When a slave processes a IsCommitted request and it is still recoverying the Transaction store, it will block the clients request for this timeout period.
MasterVoteDelay 1000 to 60000 When a node has requested to be master it will wait this timeout period in milliseconds for the peers to agree.
MasterWaitTimeout 1000 to 600000 When the master is lost from the cluster and the remaining peers detect that the master has the latest state they will wait for this time period for the master to reconnect. If the master fails to reconnect in this time period a new master is elected
PublishQueueEnabled True or False If enabled the slaves will queue publish requests prior to committing them to the cluster
QueueSize 100 to 1000 Number of events outstanding to be processed by the clusters internal queue before sending flow control requests back
SecureHandshake True or False If true, when peers connect they will peform a secure handshake to ensure the connection is valid. This is the prefered and secure option. Disabling this would only be recommended in debug mode.
SeperateLog True or False Create a seperate log file for cluster events. Default is false.
StateChangeScan 10000 to NO_MAX When a realm loses master or slave state then after this timeout all cluster based connections will be disconnected. If the realm reenters the cluster then the disconnect timeout is aborted.
SyncPingSize 100 to 10000 Number of events sent before a cluster sync occurs
TransactionSync True or False Make all transactional based events sync across the cluster
     
Comet Config    
BufferSize 1024 to 100*1024 The buffer size for comet request.
EnableLogging NO_MIN to NO_MAX Enables logging of all comet queries
Timeout 10000 to NO_MAX The timeout for a comet connection.
     
Connection Config    
AllowBufferReuse True or False If set to true then buffers will be allocated from the buffer pool and once finished with returned to the pool. If set to false then buffers are allocated on the fly and then left for the system to free them. It is best to leave this set to true.
BufferManagerCount 1 to 256 The number of Buffer Managers that the server will allocate. This is used during startup to size and manage the netowrk buffers.
BufferPoolSize 100 to 10000 The underlying Nirvana IO utilizes buffers from a pool. By default we preload the pool with this number of buffers. As the reads/writes require buffers they are allocated from this pool, then once used are cleared and returned. If the size is too small we end up creating and destroying buffers, if too large we have a pool of buffers which are not used taking up memory.
BufferQueueSize 10 to 1000 Number of buffers to queue before we stop reading from the socket.
BufferSize 1024 to 20480 This specifies the default size of the network buffers that Nirvana uses for its NIO. If small, then Nirvana will require more buffers (up to the maximum specified by BufferPoolSize) to send an event. If too large, then memory may be wasted on large, unused buffers. These buffers are reused automatically by the server, and are used to transfer data from the upper application layer to the network. So, for example, the server might use all BufferPoolSize buffers to stream from 1 application level buffer (depending on the relative sizes of the buffers). An efficient size would be about 40% more than the average client event, or 5K (whichever is largest).
ConnectionDelay 10 to 60000 When the server has exceeded the connection count, how long to hold on to the connection before disconnecting. Default is 60000.
HandshakeTimeout 1000 to NO_MAX \tThe number of milliseconds that the server will wait for the session to be established. Default is 1000, i.e. 1 second
IdleDriverTimeout 120000 to NO_MAX Specifies the time in milliseconds that a communications driver can be idle before being deemed as inactive. When this happens the server will automatically close and remove the driver
IdleSessionTimeout 10000 to NO_MAX If there has been no communication from a client for the configured number of milliseconds, the client is deemed idle and is disconnected. This typically occurs when there are network issues between a client and the server.
KeepAlive 5000 to NO_MAX The number of milliseconds between the server will wait before sending a heartbeat. Default is 60000.
MaxBufferSize 1024 to NO_MAX The maximum buffer size that the server will accept. Default is 1048576.
MaxNoOfConnections -1 to NO_MAX Sets the maximum concurrent connections to the server, -1 indicates no restriction, default is -1.
MaxWriteCount 5 to 100 When writing many events to a client the write pool thread may continue to send the events before returning to the pool to process other clients requests. So, for example if its set to 5, then the thread will send 5 events from the clients queue to the client before returning to the pool to process another request.
NetworkMonitorThreads 2 to 100 The number of threads to allocate to flushing client data, Please note this will only take effect after a restart
OutputBlockSize 100 to NO_MAX The size of the application-level buffer used when streaming events. If the size is exceeded during streaming, the buffer is immediately emptied, and its contents transmitted over the network. Typically, each connection has its own buffer for outbound streaming. Default is 1400.
QueueHighWaterMark 2 to NO_MAX The number of events in a client output queue before the server stops sending events. Default is 100.
QueueLowWaterMark 1 to NO_MAX The number of events in the clients queue before the server resumes sending events. Default is 50.
ReadCount 1 to 20 Number of times the thread will loop around waiting for an event to be delivered before returning
UseDirectBuffering True or False If true the server will allocate DirectByteBuffers to use for network I/O, else the server will use HeapByteBuffers, the main difference is where the JVM will allocate memory for the buffers the DirectByteBuffers perform better
whEventThresholdCount 1 to 2000 Number of events to exceed in the whEventThresholdTime to detect a peak
whEventThresholdTime 1 to 2000 Number of milliseconds to sample the event rate to detect peaks
whMaxEventsBeforeFlush 1 to 10000 Total number of events that can be sent before a flush must be done
whMaxEventsPerSecond NO_MIN to NO_MAX Specifies the total number of events per second that a realm will send to clients before switching modes into peak mode
whMaxTimeBetweenFlush 1 to 1000 Total number of milliseconds to wait before a flush is done
whPeakTrailDelay 100 to 5000 When a peak is detected how long to stay in this state before returning to normal
WriteHandlerType 1 to 5 Specifies the type of write handler to use
     
Data Stream Config    
MaxSessionIdSize 5 to 30 Maximum size of the session Id used to uniquely identify the clients
MonitorTimer 1000 to 120000 Time interval in milliseconds to scan the data group configuration looking for idle / completed streams
ParallelFanoutThreshold 10 to 10000 Number of streams when the server will use parallel fanout
ParallelWorkers 1 to 64 Maximum size of the session Id used to uniquely identify the clients
     
Event Storage    
ActiveDelay 100 to NO_MAX The time in milliseconds that an active channel will delay between scans. Default is 1000.
AutoDeleteScan 1000 to 500000 Specifies the number of milliseconds between scans on AutoDelete stores to see if they should be deleted
AutoMaintenanceThreshold 0 to 100 Sets the percentage free before an auto maintenance is performed, applies to internal stores only
CacheAge 1000 to NO_MAX The time in ms that cached events will be kept in memory for. Default is 86400000.
EnableStoreCaching True or False If true the server will try and cache events in memory after they have been written/read
EnableStoreReadBuffering True or False If true the server will buffer the reads from the store. This will increase replay performance greatly
IdleDelay 5000 to NO_MAX The time in milliseconds that an idle channel will delay between scans. Default is 60000.
JMSEngineAutoPurgeTime 5000 to 600000 Defines the interval between clean up of JMS Engine resources
PageSize 10 to 100000 The size in page size to use for the event store
StoreReadBufferSize 1024 to 2*1024*1024 Size of the buffer to use during reads from the store
SyncBatchSize 1 to 1000 Specifies the maximum size before the sync call is made
SyncServerFiles True or False If true the server will sync each file operation for its internal files
SyncTimeLimit 1 to 1000 Specifies the maximum time in milliseconds that will be allowed before the sync is called
ThreadPoolSize 1 to 4 The number of threads allocated to perform the management task on the channels. Default is 1.
     
Fanout Values    
ConcurrentUser 1 to NO_MAX The number of client threads allowed to execute concurrently in the server. Default is 5.
ConnectionGrouping True or False If true allows the server to group connections with the same selector providing improved performance
JMSQueueHWWeight NO_MIN to NO_MAX The weight value applied to the High Water mark when detecting when a client exceeds the limit
JMSQueueMaxMultiplier 1 to 10 The multiplier used on the High Water mark when processing events from a JMS Engine Queue/Topic
MaximumDelayInWrite 1 to 5000 The number of milliseconds an event will wait in a queue before it will be processed
ParallelThreadPoolSize 2 to 64 Specifies the number of threads to use within the thread pool. Restart Required
ParallelThreshold 20 to 10000 Specifies the number of connections to a channel before the server will use the parallel fanout engine
ParallelUseGlobalPool True or False If true all channels use a common pool else all channel have there own pool. Restart required
PeakPublishDelay 0 to NO_MAX When clients start to hit high water mark how long to delay the publisher to allow the client time to catch up
PublishDelay 0 to NO_MAX How long to delay the publisher when subscribers queue start to fill, in milliseconds. Default is 10.
PublishExpiredEvents True or False Publish expired events at server startup. Default is true.
RoundRobinDelivery True or False Use a round robin approach to event delivery. Default is false.
SendEndOfChannelAlways True or False Always send a End Of Channel, even if we find no matches within the topic
SendPubEventsImmediately True or False Send publish events immediately
SyncQueueDelay 10 to 3600000 Maximum number of milliseconds the queue publisher will be delayed
SyncQueuePublisher True or False If true then the queue publisher will be sync with the queue consumers
     
Global Values    
AllowRealmAdminFullAccess True or False Any subject with Admin ACL applied has full access to all objects within the realm.
CacheJoinInfoKeys True or False If enabled we cache join key information between events passed over joins. This reduces the number of objects created
DisableExplicitGC True or False If enabled the server will call the Garbage Collector at regular intervals to keep memory usage down
EnableDNSLookups True or False If enabled the server will attempt to perform a DNS lookup when a client connects to resolve the IP address to a hostname. In some instances this may slow down the initial connection.
ExtendedMessageSelector True or False If true, allows the server to use the extended message selector syntax. Default is false.
HTTPCookieSize 14 to 100 The size in bytes to be used by nhp(s) cookies
NanoDelayBase 10000 to 1000000 This number represents the number of nano seconds in a millisecond. Typically this is 1,000,000 however, it can be used to increase or decrease the internal delays used by Nirvana.
NHPScanTime 5000 to NO_MAX The number of milliseconds that the server will wait before scanning for client timeouts. Default is 5000, i.e. 5 seconds
NHPTimeout 2000 to NO_MAX The number of milliseconds the server will wait for client authentication. Default is 120000, i.e. 2 minutes.
SendRealmSummaryStats True or False \tIf true sends the realms status summary updates. Default is false.
ServerStateFlush 50 to 1000 Specifies the time in milliseconds between scans to save the servers state files
ServerTime True or False Allow the server to send the current time to the clients. Default is true.
StampDictionary True or False Place Nirvana details into the dictionary, default is false.
StampHost True or False Stamps the header with the publishing host (true/false)
StampTime True or False Stamps the header with the current time (true/false)
StampUser True or False Stamps the header with the publishing user (true/false)
StatusBroadcast 2000 to NO_MAX The number of ms between status events being published. Default is 5000, i.e. every 5 seconds.
StatusUpdateTime 2000 to NO_MAX The number of ms between status events being written to disk. Status events provide a history of the realm's state, the default for this is Long.MAX_VALUE, i.e. never written to disk.
SupportOlderClients True or False Allow the server to support older clients. Default is true.
     
Inter-Realm Comms Config    
EstablishmentTime 10000 to 120000 Time for an inter realm link to be initially established.
KeepAliveInterval 1000 to 120000 Time interval where if nothing is sent a Keep Alive event is sent
KeepAliveResetTime 10000 to 180000 If nothing has been received for this time the connection is deemed closed
MaximumReconnectTime 1000 to 50000 The maximum number of milliseconds to wait before trying to reestablish a connection.
MinimumReconnectTime 100 to 10000 The minimum time to wait before establishing a connection.
Timeout 60000 to 180000 If no events received within this time limit the link is assumed dead and will be closed.
WriteDelayOnFail True or False If true the comms will wait for the link to re establish.
WriteDelayTimeout 1000 to 60000 The maximum time to wait in a write of the link has dropped.
     
JVM Management    
AutoThreadDumpOnExit True or False Defines if a thread dump is produced when the server exits.
EmergencyThreshold 80 to 99 The memory threshold when the server starts to agressively scan for objects to release. Default is 94, i.e. 94%
EnableJMX True or False Enable JMX beans within the server
ExitOnDiskIOError True or False If true, the server will exit if it gets a I/O Exception. Default is true
ExitOnMemoryError True or False If true, the server will exit if it gets an out of memory exception. Default is true.
IORetryCount 2 to 100 Number of times an file I/O operation will be attemptd before aborting
IOSleepTime 100 to 60000 Time between disk I/O operations if it fails
JMXRMIServerURLString NO_MIN to NO_MAX JNDI Lookup URL for the JMX Server to use, Please refer to sun for more documentation of this URL
MemoryMonitoring 60 to 30000 Number of milliseconds between monitoing memory usage on the realm. Default is 2000.
ThrottleAllPublishersAtThreshold True or False Defines if publishers will be throttled back when memory emergency threashold is reached
WarningThreshold 70 to 95 The memory threshold when the server starts to scan for objects to release. Default is 85, i.e. 85%.
     
Join Config    
ActiveThreadPoolSize 1 to NO_MAX The number of threads to be assigned for the join recovery. Default is 2.
IdleThreadPoolSize 1 to NO_MAX The number of threads to manage the idle and reconnection to remote servers. Default is 1.
MaxEventsPerSchedule 1 to NO_MAX Number of events that will be sent to the remote server in one run. Default is 50.
MaxQueueSizeToUse 1 to NO_MAX The maximum events that will be queued on behalf of the remote server. Default is 100.
UseQueuedLocalJoinHandler True or False \tSpecifies whether to use a queued join event handler. True will enable source channels and destination channels to be process events independently
     
Logging Config    
customAuditTag NO_MIN to NO_MAX The tag to mark Audit log entries with
customFailureTag NO_MIN to NO_MAX The tag to mark Failure log entries with
customFatalTag NO_MIN to NO_MAX The tag to mark Fatal log entries with
customInformativeTag NO_MIN to NO_MAX The tag to mark Informative log entries with
customLogTag NO_MIN to NO_MAX The tag to mark Log log entries with
customSecurityTag NO_MIN to NO_MAX The tag to mark Security log entries with
customSuccessTag NO_MIN to NO_MAX The tag to mark successful log entries with
customWarningTag NO_MIN to NO_MAX The tag to mark Warning log entries with
DefaultLogSize NO_MIN to NO_MAX The default size of the log in bytes
EmbedTag True or False Whether to include the type tag in the log message
EnableLog4J True or False If enabled will intercept log messages and pass to Log4J as well
fLoggerLevel 0 to 7 The server logging level, between 0 and 7 with 0, indicating very verbose, and 7 inidicating very quiet. Default is 1.
LogManager 0 to 2 The Log manager to use for rolling log files:
  • 0-ROLLING_OLD : Appends _old to the log name for the last log. Only two log files (one active and one old) are possible under this log manager e.g. nirvana.log_old.
  • 1-ROLLING_DATE : Appends a human readable form of the date to the log name when the log is rolled. e.g. nirvana.logWed-Sep-14-02-31-40-117-BST-2011
  • 2-ROLLING_NUMBER : Appends a sequence number to the log. e.g. LOGNAME.log3 is the third most recently rolled log file. These indexes update each time a log is rolled.
LogName NO_MIN to NO_MAX The base name for the log files to create.
RolledLogFileDepth NO_MIN to NO_MAX The number of log files to keep on disk when using log rolling. Oldest entries will be deleted when new files are created.
     
Plugin Config    
EnableAccessLog True or False Defines if plugin access log produced
EnableErrorLog True or False Defines if plugin error log produced
EnablePluginLog True or False Defines if plugin status log produced
MaxNumberOfPluginThreads 10 to 10000 Maximum number of threads to allocate to the plugin manager
PluginTimeout 1000 to 30000 Time in milliseconds that the plugin will read from a client
     
Protobuf Config    
CacheEventFilter True or False Hold the Protocol Buffer filter cache in memory. Default true
FilterProtobufEvents True or False Allows the server to filter on Protocol Buffers. Default is true
MaximumProtobufBuilders NO_MIN to NO_MAX The maximum amount of builders per descriptor file. Default 4
MinimumProtobufBuilders NO_MIN to NO_MAX The minimum amount of builders per descriptor file. Default 2
ProtobufDescriptorsInputDir NO_MIN to NO_MAX The folder to search for Protocol Buffer descriptor files to parse incoming messages.
ProtobufDescriptorsOutputDir NO_MIN to NO_MAX The folder for the server to put the combined Protocol Buffer descriptor file for serving out to clients.
UpdateDescriptorsInterval 1000 to NO_MAX The time in milliseconds between checking the Protocol Buffer directory for updates. Default is 60000
     
Proxy Forward Config    
BufferSize 1024 to 20480 The size of the buffer to use for the proxied events
FlushTimeout 10000 to 120000 Time to wait for a flush to complete
     
Thread Pool Config    
CommonPoolThreadSize 5 to 1000 Maximum number of thread to allocate to the common thread pool
ConnectionThreadPoolMaxSize 10 to NO_MAX The maximum number of threads allocated to establish client connections
ConnectionThreadPoolMinSize 4 to 100 The minimum number of threads allocated to establish client connections
ConnectionThreadWaitTime 10000 to 300000 The time for the thread to wait for the client to finalise the connection
ConnectionWaitHostCount 10 to 10000 The number of outstanding connection establish requests that a single host can have at any one time
EnableConnectionThreadPooling True or False If true then if NIO is available it will be available for interfaces to use it and then all reads/writes will be done via the Read/Write thread pools. If NIO is not available then a limited used write thread pool is used.
ReadThreadPoolMaxSize 4 to NO_MAX The maximum number of threads that will be allocated to the read pool. If NIO is not available this should be set to the maximum number of clients that is expected to connect. If NIO is available then this number would be best to keep under 20.
ReadThreadPoolMinSize 4 to NO_MAX This is the number of threads that will always be present in the read thread pool. If this is too small then the thread pool will be requesting new threads from the idle queue more often.
SchedulerPoolSize 1 to 4 The number of threads assigned to the scheduler, default is 2.
ThreadIdleQueueSize 5 to 50 When threads are released from various pools since they no longer need them they end up in the idle queue. If this idle queue exceeds this number the threads are destroyed. By specifying this number to be large enough to accommodate enough idle threads so that if any thread pool requires to expand then they can be reused.
WriteThreadPoolMaxSize 5 to NO_MAX The maximum number of threads that will be allocated to the write pool. If NIO is not available this should be set to the maximum number of clients that is expected to connect. If NIO is available then this number would be best to keep under 20.
WriteThreadPoolMinSize 5 to NO_MAX This is the number of threads that will always be present in the write thread pool. If this is too small then the thread pool will be requesting new threads from the idle queue more often.
     

Double-clicking on the item you wish to modify in the configuration group will provide you with a dialog window where the new value can be entered. Configuration items will be validated to check whether they are within the correct range of values. If you enter an incorrect value you will be notified.