What is New in NDB Cluster • ReservedFiredTriggers • ReservedLocalScans • ReservedTransactionBufferMemory . See the descriptions of the parameters just listed for further information. Backups using multiple LDMs create subdirectories, one per LDM, under the  BACKUP/ BACKUP- backup_id /  directory.  ndb_restore  now detects these subdirectories automatically, and if they exist, attempts to restore the backup in parallel; see Section 23.4.23.3, “Restoring from a backup taken in parallel” , for details. (Single-threaded backups are restored as in previous versions of  NDB .) It is also possible to restore backups taken in parallel using an  ndb_restore  binary from a previous version of NDB Cluster by modifying the usual restore procedure; Restoring a parallel backup serially, provides information on how to do this. Upgrades to the new format are relatively seamless, and should seldom if ever require manual intervention, as the management server continues to be able to read the old format without issue. A downgrade from NDB 8.0.18 (or later) to an older version of the NDB Cluster software requires manual removal of any binary configuration files or, alternatively, starting the older management server binary with the  --initial  option. For more information, see Section 23.2.7, “Upgrading and Downgrading NDB Cluster” . Previously, the recommended node IDs for management nodes were 49 and 50. These are still supported for management nodes, but using them as such limits the maximum number of data nodes to 142; for this reason, it is now recommended that node IDs 145 and 146 are used for management nodes. As part of this work, the format used for the data node  sysfile  has been updated to version 2. This file records information such as the last global checkpoint index, restart status, and node group membership of each node (see NDB Cluster Data Node File System Directory). • Backups using multiple LDMs per data node.  NDB  backups can now be performed in a parallel fashion on individual data nodes using multiple local data managers (LDMs). (Previously, backups were done in parallel across data nodes, but were always serial within data node processes.) No special syntax is required for the  START BACKUP  command in the  ndb_mgm  client to enable this feature, but all data nodes must be using multiple LDMs. This means that data nodes must be running  ndbmtd  ( ndbd is single-threaded and thus always has only one LDM) and they must be configured to use multiple LDMs before taking the backup; you can do this by choosing an appropriate setting for one of the multi- threaded data node configuration parameters  MaxNoOfExecutionThreads  or  ThreadConfig . • Binary configuration file enhancements.   Beginning with NDB 8.0.18, a new format is used for the management server’s binary configuration file. Previously, a maximum of 16381 sections could appear in the cluster configuration file; now the maximum number of sections is 4G. This is intended to support larger numbers of nodes in a cluster than was possible before this change. • Increased number of data nodes.   NDB 8.0.18 increases the maximum number of data nodes supported per cluster to 144 (previously, this was 48). Data nodes can now use node IDs in the range 1 to 144, inclusive. • RedoOverCommitCounter and RedoOverCommitLimit changes.   Due to ambiguities in the semantics for setting them to 0, the minimum value for each of the data node configuration parameters RedoOverCommitCounter  and  RedoOverCommitLimit  has been increased to 1, beginning with NDB 8.0.19. 3943