NDB Cluster Configuration Files • rep : Replication thread ( SUMA  kernel block). Prior to NDB 8.0.23, asynchronous replication operations are always handled by a single, dedicated thread. Beginning with NDB 8.0.23, this thread can be combined with the main thread (see range information). • NDB 8.0.22 and earlier : 1 only. • NDB 8.0.23 and later : 0-1. • io : File system and other miscellaneous operations. These are not demanding tasks, and are always handled as a group by a single, dedicated I/O thread. • watchdog : Parameters settings associated with this type are actually applied to several threads, each having a specific use. These threads include the  SocketServer  thread, which receives connection setups from other nodes; the  SocketClient  thread, which attempts to set up connections to other nodes; and the thread watchdog thread that checks that threads are progressing. • idxbld : Offline index build threads. Unlike the other thread types listed previously, which are permanent, these are temporary threads which are created and used only during node or system restarts, or when running  ndb_restore --rebuild-indexes . They may be bound to CPU sets which overlap with CPU sets bound to permanent thread types. •Offline index build threads are not bound if the I/O thread is also not bound, and these threads use any available cores. •If the I/O thread is bound, then the offline index build threads are bound to the entire set of bound threads, due to the fact that there should be no other tasks for these threads to perform. •If, following the change, the number of LDM threads remains the same as before, nothing more than a simple node restart (rolling restart, or  N ) is required to implement the change. 4138 Changing  ThreadCOnfig  normally requires a system initial restart, but this requirement can be relaxed under certain cirumstances: Range: 0 - 1. If  idxbld  is not specified, the default behavior is as follows: thread_prio ,  realtime , and  spintime  values cannot be set for offline index build threads. In addition,  count  is ignored for this type of thread. Range: 1 only. Range: 1 only. Setting  rep  to 0 and  main  to 1 causes the  rep  blocks to be placed into the  main  thread; the combined thread is shown in the  ndbinfo.threads  table as  main_rep . This is effectively the same as setting  main  equal to 1 and  rep  equal to 0. It is also possible to set both  main  and  rep  to 0, in which case both threads are placed in the first recv  thread; the resulting combined thread is named  main_rep_recv  in the  threads  table. Range: