NDB Cluster Configuration Files 4231 When setting up shared memory segments, a node ID, expressed as an integer, is used to identify uniquely the shared memory segment to use for the communication. There is no default value. If  UseShm is enabled, the shared memory key is calculated automatically by  NDB . Each SHM connection has a shared memory segment where messages between nodes are placed by the sender and read by the reader. The size of this segment is defined by  ShmSize . The default value is 4MB. When receiving, the time to wait before sleeping, in microseconds. This parameter was used formerly to override operating system signal numbers; in NDB 8.0, it is no longer used, and any setting for it is ignored. Restart types.   Information about the restart types used by the parameter descriptions in this section is shown in the following table: Table 23.22 NDB Cluster restart types Symbol Restart Type Description N Node The parameter can be updated using a rolling restart (see Section 23.5.5, “Performing • ShmSize • ShmSpinTime • SigNum Version (or later) NDB 8.0.13 Type or units bytes Default 4M Range 64K - 4294967039 (0xFFFFFEFF) Restart Type N (NDB 8.0.13) Version (or later) NDB 8.0.13 Type or units integer Default 0 Range 0 - 2000 Restart Type N (NDB 8.0.13) Version (or later) NDB 8.0.13 Type or units unsigned Default [...] Range 0 - 4294967039 (0xFFFFFEFF) Deprecated Yes (in NDB 7.6) Restart Type N (NDB 8.0.13) Restart Type N (NDB 8.0.13)