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• BackupDataDir 

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## Data Memory, Index Memory, and String Memory 

This parameter specifies the directory in which backups are placed. 

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## Important 

The string ’ /BACKUP ’ is always appended to this value. For example, if you set the value of BackupDataDir  to /var/lib/cluster-data , then all backups are stored under /var/lib/cluster-data/BACKUP . This also means that the effective  default backup location is the directory named BACKUP  under the location specified by the FileSystemPath  parameter. 

DataMemory  and IndexMemory  are [ndbd]  parameters specifying the size of memory segments used to store the actual records and their indexes. In setting values for these, it is important to understand how DataMemory  is used, as it usually needs to be updated to reflect actual usage by the cluster. 

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• DataMemory 

## Note 

IndexMemory  is deprecated, and subject to removal in a future version of NDB Cluster. See the descriptions that follow for further information. 

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This parameter defines the amount of space (in bytes) available for storing database records. The entire amount specified by this value is allocated in memory, so it is extremely important that the machine has sufficient physical memory to accommodate it. 

The memory allocated by DataMemory  is used to store both the actual records and indexes. There is a 16-byte overhead on each record; an additional amount for each record is incurred because it is stored in a 32KB page with 128 byte page overhead (see below). There is also a small amount wasted per page due to the fact that each record is stored in only one page. 

