Friday, February 23, 2007

How Netbackup works???

I was trying to simplify the understanding of the netbackup processes. Here's what I could manage.

On master server

bprd must be running.

ltid must be running.

Scheduled backup operations

bprd -> bpsched -> consults bpdbm to determine
1. which jobs need to be run.
2. figure out req of jobs to be run.

This is automated and is governed bu the global Wakeup interval. If bpsched finds that there is no job to be done, it quitely exits.

bpsched now starts another bpsched (lets call it bpsched-B) which is given the onus of executing the tasks.

bpsched-B also spawns multiple bpscheds,one for each task it needs to spawn.

Each of these bpsched starts a bpcd process on the media server required by the policy. The media server is determined by the storage unit.

bpcd -> bpbrm -> bptm (on media-server) -> bpcd (client) -> bpbkar to start sending data ->
meta data to bpbrm ->bpdbm (update catalog)

At the same time

bptm (on media-server)
bptm (on media server) -> vmd (media to be used).
bptm (on media server) -> ltid (robotic communication, tape request).
bptm (on media server) -> tpreq

bptm (child process) -> bpbkar on client and receiving and writing out to the data buffers.

Once bpbkar stops sending out data to the bptm on the media server, it exits and the bpsched child will now communicate to its parent bpsched-B and bpsched-B will check if there are other jobs it scheduled running. If no it send a signal to the bpsched-A.

Incase there are no more jobs to be scheduled, bpsched-A exits.

References : Veritas Troubleshooting Guide and this post from Kemal Badur.


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