B.2 Data Node Configuration Parameters

• Arbitration: How arbitration should be performed to avoid split-brain issues in the event of node failure.

• ArbitrationTimeout: Maximum time (milliseconds) database partition waits for arbitration signal

• BackupDataBufferSize: Default size of databuffer for a backup (in bytes)

• BackupDataDir: Path to where to store backups. Note that the string '/BACKUP' is always appended to this setting, so that the *effective* default is FileSystemPath/BACKUP.

• BackupDiskWriteSpeedPct: Sets the percentage of the data node's allocated maximum write speed (MaxDiskWriteSpeed) to reserve for LCPs when starting abackup.

• BackupLogBufferSize: Default size of log buffer for a backup (in bytes)

• BackupMaxWriteSize: Maximum size of file system writes made by backup (in bytes)

• BackupMemory: Total memory allocated for backups per node (in bytes)

• BackupReportFrequency: Frequency of backup status reports during backup in seconds

• BackupWriteSize: Default size of file system writes made by backup (in bytes)

• BatchSizePerLocalScan: Used to calculate the number of lock records for scan with hold lock

• BuildIndexThreads: Number of threads to use for building ordered indexes during a system or node restart. Also applies when running ndb_restore --rebuild-indexes. Setting this parameter to 0 disables multithreaded building of ordered indexes.

• CompressedBackup: Use zlib to compress backups as they are written

• CompressedLCP: Write compressed LCPs using zlib

• ConnectCheckIntervalDelay: Time between data node connectivity check stages. Data node is considered suspect after 1 interval and dead after 2 intervals with no response.

• CrashOnCorruptedTuple: When enabled, forces node to shut down whenever it detects a corrupted tuple.

• DataDir: Data directory for this node

• DataMemory: Number of bytes on each data node allocated for storing data; subject to available system RAM and size of IndexMemory.

• DefaultHashMapSize: Set size (in buckets) to use for table hash maps. Three values are supported: 0, 240, and 3840. Intended primarily for upgrades and downgrades to and from NDB 7.2.7+; see the documentation before attempting to use.

• DictTrace: Enable DBDICT debugging; for NDB development

• DiskCheckpointSpeed: Bytes allowed to be written by checkpoint, per second

• DiskCheckpointSpeedInRestart: Bytes allowed to be written by checkpoint during restart, per second

• DiskIOThreadPool: Number of unbound threads for file access (currently only for Disk Data); known as IOThreadPool before MySQL Cluster NDB 6.4.3.

• Diskless: Run without using the disk

• DiskPageBufferEntries: Number of 32K page entries to allocate in DiskPageBufferMemory. Very large disk transactions may require increasing this value.

• DiskPageBufferMemory: Number of bytes on each data node allocated for the disk page buffer cache

• DiskSyncSize: Amount of data written to file before a synch is forced

• EventLogBufferSize: Size of circular buffer for NDB log events within data nodes.

• ExecuteOnComputer: String referencing an earlier defined COMPUTER

• ExtraSendBufferMemory: Memory to use for send buffers in addition to any allocated by TotalSendBufferMemory or SendBufferMemory. Default (0) allows up to 16MB.

• FileSystemPath: Path to directory where the data node stores its data (directory must exist)

• FileSystemPathDataFiles: Path to directory where the data node stores its Disk Data files. The default value is FilesystemPathDD, if set; otherwise, FilesystemPath is used if it is set; otherwise, the value of DataDir is used.

• FileSystemPathDD: Path to directory where the data node stores its Disk Data and undo files. The default value is FileSystemPath, if set; otherwise, the value of DataDir is used.

• FileSystemPathUndoFiles: Path to directory where the data node stores its undo files for Disk Data. The default value is FilesystemPathDD, if set; otherwise, FilesystemPath is used if it is set; otherwise, the value of DataDir is used.

• FragmentLogFileSize: Size of each redo log file

• HeartbeatIntervalDbApi: Time between API node-data node heartbeats. (API connection closed after 3 missed heartbeats)

• HeartbeatIntervalDbDb: Time between data node-to-data node heartbeats; data node considered dead after 3 missed heartbeats

• HeartbeatOrder: Sets the order in which data nodes check each others' heartbeats for determining whether a given node is still active and connected to the cluster. Must be zero for all data nodes or distinct nonzero values for all data nodes; see documentation for further guidance.

• HostName: Host name or IP address for this data node.

• Id: Number identifying the data node (Id). Now deprecated; use NodeId instead.

• IndexMemory: Number of bytes on each data node allocated for storing indexes; subject to available system RAM and size of DataMemory.

• IndexStatAutoCreate: Enable/disable automatic statistics collection when indexes are created.

• IndexStatAutoUpdate: Monitor indexes for changes and trigger automatic statistics updates

• IndexStatSaveScale: Scaling factor used in determining size of stored index statistics.

• IndexStatSaveSize: Maximum size in bytes for saved statistics per index.

• IndexStatTriggerPct: Threshold percent change in DML operations for index statistics updates. The value is scaled down by IndexStatTriggerScale.

• IndexStatTriggerScale: Scale down IndexStatTriggerPct by this amount, multiplied by the base 2 logarithm of the index size, for a large index. Set to 0 to disable scaling.

• IndexStatUpdateDelay: Minimum delay between automatic index statistics updates for a given index. 0 means no delay.

• InitFragmentLogFiles: Initialize fragment logfiles (sparse/full)

• InitialLogFileGroup: Describes a log file group that is created during an initial start. See documentation for format.

• InitialNoOfOpenFiles: Initial number of files open per data node. (One thread is created per file)

• InitialTablespace: Describes a tablespace that is created during an initial start. See documentation for format.

• LateAlloc: Allocate memory after the connection to the management server has been established.

• LcpScanProgressTimeout: Maximum time that local checkpoint fragment scan can be stalled before node is shut down to ensure systemwide LCP progress. Use 0 to disable.

• LockExecuteThreadToCPU: In NDB 6.3, the ID of the CPU to run the execution thread; in NDB 7.0 and later, a comma-delimited list of CPU IDs

• LockMaintThreadsToCPU: CPU ID indicating which CPU runs the maintenance threads

• LockPagesInMainMemory: Previously: If set to true/1, then NDB Cluster data is not swapped out to disk. In MySQL 5.0.36/5.1.15 and later: 0=disable locking, 1=lock after memory allocation, 2=lock before memory allocation

• LogLevelCheckpoint: Log level of local and global checkpoint information printed to stdout

• LogLevelCongestion: Level of congestion information printed to stdout

• LogLevelConnection: Level of node connect/disconnect information printed to stdout

• LogLevelError: Transporter, heartbeat errors printed to stdout

• LogLevelInfo: Heartbeat and log information printed to stdout

• LogLevelNodeRestart: Level of node restart and node failure information printed to stdout

• LogLevelShutdown: Level of node shutdown information printed to stdout

• LogLevelStartup: Level of node startup information printed to stdout

• LogLevelStatistic: Level of transaction, operation, and transporter information printed to stdout

• LongMessageBuffer: Number of bytes allocated on each data node for internal long messages

• MaxAllocate: Maximum size of allocation to use when allocating memory for tables

• MaxBufferedEpochs: Allowed numbered of epochs that a subscribing node can lag behind (unprocessed epochs). Exceeding will cause lagging subscribers to be disconnected.

• MaxBufferedEpochBytes: Total number of bytes allocated for buffering epochs.

• MaxDiskWriteSpeed: Maximum number of bytes per second that can be written by LCP and backup when no restarts are ongoing.

• MaxDiskWriteSpeedOtherNodeRestart: Maximum number of bytes per second that can be written by LCP and backup when another node is restarting.

• MaxDiskWriteSpeedOwnRestart: Maximum number of bytes per second that can be written by LCP and backup when this node is restarting.

• MaxDMLOperationsPerTransaction: Limit size of a transaction; aborts the transaction if it requires more than this many DML operations. Set to 0 to disable.

• MaxLCPStartDelay: Time in seconds that LCP polls for checkpoint mutex (to allow other data nodes to complete metadata synchronization), before putting itself in lock queue for parallel recovery of table data.

• MaxNoOfAttributes: Suggests a total number of attributes stored in database (sum over all tables)

• MaxNoOfConcurrentIndexOperations: Total number of index operations that can execute simultaneously on one data node

• MaxNoOfConcurrentOperations: Maximum number of operation records in transaction coordinator

• MaxNoOfConcurrentScans: Maximum number of scans executing concurrently on the data node

• MaxNoOfConcurrentSubOperations: Maximum number of concurrent subscriber operations

• MaxNoOfConcurrentTransactions: Maximum number of transactions executing concurrently on this data node, the total number of transactions that can be executed concurrently is this value times the number of data nodes in the cluster.

• MaxNoOfFiredTriggers: Total number of triggers that can fire simultaneously on one data node

• MaxNoOfLocalOperations: Maximum number of operation records defined on this data node

• MaxNoOfLocalScans: Maximum number of fragment scans in parallel on this data node

• MaxNoOfOpenFiles: Maximum number of files open per data node.(One thread is created per file)

• MaxNoOfOrderedIndexes: Total number of ordered indexes that can be defined in the system

• MaxNoOfSavedMessages: Maximum number of error messages to write in error log and maximum number of trace files to retain

• MaxNoOfSubscribers: Maximum number of subscribers (default 0 = MaxNoOfTables * 2)

• MaxNoOfSubscriptions: Maximum number of subscriptions (default 0 = MaxNoOfTables)

• MaxNoOfTables: Suggests a total number of NDB tables stored in the database

• MaxNoOfTriggers: Total number of triggers that can be defined in the system

• MaxNoOfUniqueHashIndexes: Total number of unique hash indexes that can be defined in the system

• MaxParallelCopyInstances: Number of parallel copies during node restarts. Default is 0, which uses number of LDMs on both nodes, to a maximum of 16.

• MaxParallelScansPerFragment: Maximum number of parallel scans per fragment. Once this limit is reached, scans are serialized.

• MaxStartFailRetries: Maximum retries when data node fails on startup, requires StopOnError = 0. Setting to 0 causes start attempts to continue indefinitely.

• MemReportFrequency: Frequency of memory reports in seconds; 0 = report only when exceeding percentage limits

• MinDiskWriteSpeed: Minimum number of bytes per second that can be written by LCP and backup.

• MinFreePct: The percentage of memory resources to keep in reserve for restarts.

• NodeGroup: Node group to which the data node belongs; used only during initial start of cluster.

• NodeId: Number uniquely identifying the data node among all nodes in the cluster.

• NoOfFragmentLogFiles: Number of 16 MB redo log files in each of 4 file sets belonging to the data node

• NoOfReplicas: Number of copies of all data in database; recommended value is 2 (default). Values greater than 2 are not supported in production.

• Numa: (Linux only; requires libnuma) Controls NUMA support. Setting to 0 permits system to determine use of interleaving by data node process; 1 means that it is determined by data node.

• ODirect: Use O_DIRECT file reads and writes when possible.

• RealtimeScheduler: When true, data node threads are scheduled as real-time threads. Default is false.

• RedoBuffer: Number bytes on each data node allocated for writing redo logs

• RedoOverCommitCounter: When RedoOverCommitLimit has been exceeded this many times, transactions are aborted, and operations are handled as specified by DefaultOperationRedoProblemAction.

• RedoOverCommitLimit: Each time that flushing the current redo buffer takes longer than this many seconds, the number of times that this has happened is compared to RedoOverCommitCounter.

• ReservedSendBufferMemory: This parameter is present in NDB code but is not enabled, and is now deprecated.

• RestartOnErrorInsert: Control the type of restart caused by inserting an error (when StopOnError is enabled)

• SchedulerExecutionTimer: Number of microseconds to execute in scheduler before sending

• SchedulerResponsiveness: Set NDB scheduler response optimization 0-10; higher values provide better response time but lower throughput

• SchedulerSpinTimer: Number of microseconds to execute in scheduler before sleeping

• ServerPort: Port used to set up transporter for incoming connections from API nodes

• SharedGlobalMemory: Total number of bytes on each data node allocated for any use

• StartFailRetryDelay: Delay in seconds after start failure prior to retry; requires StopOnError = 0.

• StartFailureTimeout: Milliseconds to wait before terminating. (0=Wait forever)

• StartNoNodeGroupTimeout: Time to wait for nodes without a nodegroup before trying to start (0=forever)

• StartPartialTimeout: Milliseconds to wait before trying to start without all nodes. (0=Wait forever)

• StartPartitionedTimeout: Milliseconds to wait before trying to start partitioned. (0=Wait forever)

• StartupStatusReportFrequency: Frequency of status reports during startup

• StopOnError: When set to 0, the data node automatically restarts and recovers following node failures

• StringMemory: Default size of string memory (0 to 100 = % of maximum, 101+ = actual bytes)

• TcpBind_INADDR_ANY: Bind IP_ADDR_ANY so that connections can be made from anywhere (for autogenerated connections)

• TimeBetweenEpochs: Time between epochs (synchronization used for replication)

• TimeBetweenEpochsTimeout: Timeout for time between epochs. Exceeding will cause node shutdown.

• TimeBetweenGlobalCheckpoints: Time between doing group commit of transactions to disk

• TimeBetweenGlobalCheckpointsTimeout: Minimum timeout for group commit of transactions to disk

• TimeBetweenInactiveTransactionAbortCheck: Time between checks for inactive transactions

• TimeBetweenLocalCheckpoints: Time between taking snapshots of the database (expressed in base-2 logarithm of bytes)

• TimeBetweenWatchDogCheck: Time between execution checks inside a data node

• TimeBetweenWatchDogCheckInitial: Time between execution checks inside a data node (early start phases when memory is allocated)

• TotalSendBufferMemory: Total memory to use for all transporter send buffers.

• TransactionBufferMemory: Dynamic buffer space (in bytes) for key and attribute data allocated for each data node

• TransactionDeadlockDetectionTimeout: Time transaction can spend executing within a data node. This is the time that the transaction coordinator waits for each data node participating in the transaction to execute a request. If the data node takes more than this amount of time, the transaction is aborted. Prior to MySQL Cluster NDB 6.2.18/6.3.24/7.0.5, values between 50 and 100 were possible, but were treated as 100.

• TransactionInactiveTimeout: Milliseconds that the application waits before executing another part of the transaction. This is the time the transaction coordinator waits for the application to execute or send another part (query, statement) of the transaction. If the application takes too much time, then the transaction is aborted. Timeout = 0 means that the application never times out.

• TwoPassInitialNodeRestartCopy: Copy data in 2 passes during initial node restart, which enables multithreaded building of ordered indexes for such restarts.

• UndoDataBuffer: Number of bytes on each data node allocated for writing data undo logs

• UndoIndexBuffer: Number of bytes on each data node allocated for writing index undo logs

• MaxNoOfExecutionThreads: For ndbmtd only, specify maximum number of execution threads

• NoOfFragmentLogParts: Number of redo log file groups belonging to this data node; value must be an even multiple of 4.

• ThreadConfig: Used for configuration of multithreaded data nodes (ndbmtd). Default is an empty string; see documentation for syntax and other information.