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Veritas NetBackup™ Logging Reference Guide

Last Published: 2018-02-16

Product(s): NetBackup (8.1.1, 8.1)

Snapshot Client backup

The following shows a typical snapshot backup process. In this scenario, the snapshot is created on the client and is then backed up to a storage unit (disk or tape) from that client. With the exception of Windows open file backups that do not use multiple data streams, all snapshots are created by a separate parent job, followed by a child job that backs up the snapshot. For non-multistreamed Windows Open File Backups, bpbrm using bpcd invokes bpfis to take a snapshot of individual drives. If you use System State or Shadow Copy Component backups, bpbkar32 creates the snapshot using Volume Shadow Copy Service (VSS). Windows Open File Backups do not require a Snapshot Client license, although they do use Snapshot Client components, such as bpfis.

The basic processing steps for snapshot creation and backup are the following (this includes Windows open file backups that employ multiple data streams):

Snapshot Client backup procedure

The NetBackup master server or primary client initiates the backup, which causes the NetBackup request daemon (bprd) to submit a backup request to the Policy Execution Manager (nbpem). nbpem processes the policy configurations.
nbpem uses nbjm to start 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. bpbrm starts bpfis through bpcd on the client.
bpfis creates a snapshot of the client data by means of a snapshot method.
bpfis contacts bprd to request transfer of bpfis state files from client to server. This operation is enabled by default.
bprd requests bpcd on the client to send a list of bpfis state files.
bprd copies each state file from the client to the master.
bpfis 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 to nbjm a child job for the backup 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 master server.
bpbrm starts the process bptm (parent) on the media server.
One of the following occurs: The next step depends on whether the media server backs up itself (bptm and bpbkar are on the same host) or the media server backs up a client that resides 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, the bptm process 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 takes the backup image from shared memory and sends it to the storage device (disk or tape).
bptm sends the backup completion status to bpbrm, which passes it to nbjm.
When nbpem receives the 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.