NDB Cluster Configuration Files completion times, and—if the rate of change is sufficiently high—in failure to complete the backup when the backup log buffer fill rate is higher than the achievable write rate. This problem can be addressed by using the  BackupDiskWriteSpeedPct  configuration parameter, which takes a value in the range 0-90 (inclusive) which is interpreted as the percentage of the node’s maximum write rate budget that is reserved prior to sharing out the remainder of the budget among LDM threads for LCPs. The LDM thread running the backup receives the whole write rate budget for the backup, plus its (reduced) share of the write rate budget for local checkpoints. The default value for this parameter is 50 (interpreted as 50%). The backup log buffer fulfills a role similar to that played by the backup data buffer, except that it is used for generating a log of all table writes made during execution of the backup. The same principles apply for writing these pages as with the backup data buffer, except that when there is no more space in the backup log buffer, the backup fails. For that reason, the size of the backup log buffer must be large enough to handle the load caused by write activities while the backup is being made. See Section 23.5.8.3, “Configuration for NDB Cluster Backups” . The default value for this parameter should be sufficient for most applications. In fact, it is more likely for a backup failure to be caused by insufficient disk write speed than it is for the backup log buffer to become full. If the disk subsystem is not configured for the write load caused by applications, the cluster is unlikely to be able to perform the desired operations. It is preferable to configure cluster nodes in such a manner that the processor becomes the bottleneck rather than the disks or the network connections. The default value for this parameter is 16MB. This parameter is deprecated, and subject to removal in a future version of NDB Cluster. Any setting made for it is ignored. • BackupLogBufferSize • BackupMemory • BackupReportFrequency Version (or later) NDB 8.0.13 Type or units bytes Default 16M Range 2M - 4294967039 (0xFFFFFEFF) Restart Type N (NDB 8.0.13) Version (or later) NDB 8.0.13 Type or units bytes Default 32M Range 0 - 4294967039 (0xFFFFFEFF) Deprecated Yes (in NDB 7.4) Restart Type N (NDB 8.0.13) Version (or later) NDB 8.0.13 4121