The various size data buffers files contain a single integer that specifies the size of each shared data buffer in bytes. The integer should be a multiple of 1024 (a multiple of 32 kilobytes is recommended).

If the SIZE_DATA_BUFFERS file exists, its contents determine the size of shared data buffers to be used for multiplexed and non-multiplexed backups.

The other SIZE_DATA_BUFFERS files (SIZE_DATA_BUFFERS_DISK, SIZE_DATA_BUFFERS_MULTCOPY, SIZE_DATA_BUFFERS_FT) allow buffer settings for particular types of backups. The values specified in these files override either the NetBackup default size or the value that is specified in SIZE_DATA_BUFFERS.

For example, SIZE_DATA_BUFFERS_DISK allows for a different value when you back up to disk instead of tape. If SIZE_DATA_BUFFERS exists but SIZE_DATA_BUFFERS_DISK does not, SIZE_DATA_BUFFERS applies to all backups. If both files exist, SIZE_DATA_BUFFERS applies to tape backups and SIZE_DATA_BUFFERS_DISK applies to disk backups. If only SIZE_DATA_BUFFERS_DISK is present, it applies to disk backups only.

The SIZE_DATA_BUFFERS_DISK file also affects NDMP to disk backups.

Perform backup and restore testing if the shared data buffer size is changed. If NetBackup media servers are not running the same operating system, test restores on each media server that may be involved in a restore operation. If a Linux/UNIX media server writes a backup to tape with a shared data buffer of 256 kilobytes, a Windows media server may not be able to read that tape.