Backup fails with status code:84 on NetApp VTL from AIX media server.

Media Server Platform: AIX 6.1

Netbackup: 7.0.1

Backup: SAP Archives

Our backups fail occasionally with status code 84 from AIX media server when taking backup on NetApp VTL but it is successful when taking backup on tape drives. 

Does shared memory setting like "SIZE_DATA_BUFFERS" and "NUMBER_DATA_BUFFERS" affect backups on VTL and AIX media server? Since "Netbackup_70_71_Tuning_guide.pdf" referes on page 132 Note: "AIX media servers do not need to tune shared memory because AIX uses dynamic memory allocation."