NDMP backups fail while backing up large number of files with the error 18 (NDMP_XDR_DECODE_ERR) and status 42

Problem

STATUS CODE 42: Veritas NetBackup (tm) NDMP backups fail while backing up directories/volumes with large number of files with the error message "Error ndmpagent (pid=8998) connection 0x081871d8 ndmp_message_process_one failed, status = 18 (NDMP_XDR_DECODE_ERR)" and a NetBackup Status Code 42, network read failed.

Overview: Veritas NetBackup™ Network Data Management Protocol (NDMP) backups fail after running for a few hours with the error message listed below, in the Error Message field and also generates and a NetBackup Status Code 42: network read failed.

Please note, the NDMP_XDR_DECODE_ERR is a generic error. The key here is Status Code 42 that's generated when the backup is in progress for a directory with a large number of files.

Error Message

On the media server, enable the bptm log file and look for the following error messages:

- Error bptm (pid=8999) media manager terminated by parent process
- Error ndmpagent (pid=8998) NDMP backup failed, path = /vol/vol1
- Error ndmpagent (pid=8998) connection 0x081871d8 ndmp_message_process_one failed, status = 18 (NDMP_XDR_DECODE_ERR)
- end writing; write time: 2:45:09 network read failed (42)

Cause

The master bpdbm process was getting too many simultaneous updates, possibly because the backup was processing a directory with a large number of small files.

Solution

To reduce the load on the bpdbm process, create the MAX_ENTRIES_PER_ADD touch file on the media server, and in the file, place the value 50000.

Note: The touch file should be created in the following directory...
Windows: install_path\Veritas\NetBackup
UNIX/Linux: /usr/openv/netbackup

By doing this, the bpbrm process requests bpdbm to add files to the catalog for every 50,000 files going to tape (the default is 5,000 and the maximum value depends on the NetBackup version).

For more details, see the NetBackup™ Backup Planning and Performance Tuning Guide, section on Adjusting the batch size for sending metadata to the NetBackup catalog.