Snapshot backup and Windows open file backups
Figure: Snapshot backup and Windows open file backup using multiple data streams shows the overall snapshot backup process. PBX (not shown in the diagram) must be running for NetBackup to operate.
A separate parent job creates all snapshots, then a child job backs up the snapshot.
The following sequence of operations is for snapshot creation and backup, including the Windows open file backups that employ multiple data streams:
The NetBackup primary server or primary client initiates the backup. This action causes the NetBackup Request Daemon bprd to submit a backup request to the NetBackup Policy Execution Manager nbpem. nbpem processes the policy configurations.
nbpem (through nbjm) starts a parent job to create the snapshot. This job is separate from the job that backs up the snapshot.
nbjm starts an instance of bpbrm through bpcd on the media server, and bpbrm starts bpfis through bpcd on the client.
bpfis creates a snapshot of the client's data by means of a snapshot method.
When bpfis is finished, it sends snapshot information and completion status to bpbrm and exits. bpbrm, in turn, reports the snapshot information and status to nbjm and exits. nbjm relays the information and status to nbpem.
nbpem submits a child job for the backup to nbjm, with a file list derived from the snapshot information. nbjm starts bpbrm to back up the snapshot.
bpbrm starts bpbkar on the client. bpbkar sends the file catalog information to bpbrm, which relays it to the NetBackup file database bpdbm on the primary server.
bpbrm starts the process bptm (parent) on the media server.
The next step depends on the following: Whether the media server backs up itself (bptm and bpbkar on the same host), or the media server backs up a client on a different host. If the media server backs up itself, bpbkar stores the snapshot-based image block by block in shared memory on the media server. If the media server backs up a client that resides on a different host, bptm on the server creates a child process of itself. The child receives the snapshot-based image from the client by means of socket communications and then stores the image block-by-block in shared memory.
The original bptm process then takes the backup image from shared memory and sends it to the storage device (disk or tape).
Information is available on how the tape request is issued.
See "Media and device management process" in the NetBackup Troubleshooting Guide.
bptm sends backup completion status to bpbrm, which passes it to nbjm.
When nbpem receives backup completion status from nbjm, nbpem tells nbjm to delete the snapshot. nbjm starts a new instance of bpbrm on the media server, and bpbrm starts a new instance of bpfis on the client. bpfis deletes the snapshot on the client, unless the snapshot is of the Instant Recovery type, in which case it is not automatically deleted. bpfis and bpbrm report their status and exit.
For more information, see the NetBackup Snapshot Manager for Data Center Administrator's Guide.
Note that Windows open file backups do not require Snapshot Client.