Considerations for multi-host backups
NetBackup recommends using up to four backup hosts for a single NAS volume.
If enough resources are not available on the backup hosts for stream distribution, then the backup job is queued until the hosts gain enough resources to start backup streams.
If a backup stream running on any backup host is canceled or suspended, then the backup streams running on all the backup hosts for that NAS volume are canceled or suspended.
If a backup stream running on any backup host fails due to an error, then the backup streams running on all the backup hosts for that NAS volume are terminated and the backup job goes into an incomplete state.
In a rolling upgrade scenario, you can upgrade the primary server to version 10.4 while the backup host pool still includes media servers and clients running older versions. Consider the following during this upgrade:
D-NAS backups run as they did in versions prior to NetBackup 10.4, using a single host.
If you upgrade one media server to NetBackup 10.4, D-NAS backups use only the upgraded server. Multi-host backups are not supported.
If you upgrade multiple media servers and clients to NetBackup 10.4, D-NAS backups use all upgraded hosts in the backup host pool.