Hernán J. Larrea

Hernán J. Larrea
Symantec Corporation has not participated
in the development of this document.

All sources will be properly mentioned at
the end of the document.

I’m Hernán J. Larrea, an IT engineer with 8 years of experience in the field. I decided to
address my career in Wintel technologies, specially Active Directory, Backup and
Recovery environments, Storage solutions and a little programming in .NET.
I’ve compiled this document since I believe it is very important for Netbackup
administrators to count with this knowledge at the time of troubleshooting, Symantec
has good articles and documents describing this processes, but compiling this in form
of slides and animations helps to concentrate the eyes and the mind, in different and
specific matters making learning much easier.
If you want to know more about me, I invite you to visit my personal website
http://www.hernanjlarrea.com.ar or my blog at http://blog.hernanjlarrea.com.ar and if
you want to email me, you can do it at [email protected]
Hernán J. Larrea
Things you need to know before thinking on the backup process.
When the NetBackup master server boots
up, a script automatically starts all services,
daemons, and programs required by
NetBackup.

The same is true on a media server:
NetBackup automatically starts additional
programs as required, including robotic
daemons.

A daemon that executes on all servers and
clients is the NetBackup client daemon, bpcd.
On UNIX clients, inetd starts bpcd automatically
so no special actions are required. On Windows
clients, bpinetd performs the same functions as
inetd.

Note that all NetBackup processes can be
started manually by running the following:

/usr/openv/netbackup/bin/bp.start_
all
Starting with NetBackup 6.0, the scheduler process bpsched is replaced by
the following new services:

nbpem service (Policy Execution Manager): creates a persistent job
worklist, starts each job when it is due (no wakeup interval), and sets a
timer for the next due job.

nbjm service (Job Manager): accepts requests from nbpem to run backup
jobs, or to run media jobs from commands such as bplabel and tpreq.
nbjm acquires resources for each job, such as storage unit, drives, media,
and client and policy resources, and executes the job.

nbrb service (Resource Broker): allocates resources in response to
requests from nbjm. nbrb acquires physical resources from nbemm (the
Enterprise Media Manager service), and manages logical resources such
as multiplex groups, maximum jobs per client, and maximum jobs per
policy. nbrb is also responsible for initiating drive unloads, and manages
pending request queues.
The NetBackup master server and the Enterprise Media Manager
(EMM) server can be on the same physical host or on different
hosts.
Master server: responsible for running jobs as configured in
NetBackup policies. The nbpem and nbjm services run only on the
master server.

EMM server: allocates resources for one or more master
servers. The EMM server is the repository for all device
configuration information. The nbemm and nbrb services run only
on the EMM server.

▪
nbemm service: centralizes resource selection. nbemm maintains devices,
media, and storage units in a relational database. Prior to NetBackup 6.0, resource
selection was handled by bpsched, bptm, ltid, and the robotic device daemons.
As you might already know, Netbackup operation implies communication across many,
many daemons and processes, here you will find what happens when a backup starts.

Even the text speaks about tape and disk
storage units, diagrams will only describe the
process for tape (the process is only different
only in one step, 15).

Even the text describes this is a backup on a
UNIX host, process is just the same for
Windows machines.
Backup process
After boot up:
EMM & Master Server
bprd
1) A start-up script launches
bprd on the master server and
ltid on the master server and all
media servers. All other
daemons and programs are
started as necessary, including
nbpem, nbjm, nbrb, and
nbemm.
1
nbpem
Media Server
ltid
Client
14
Backup process
The policy execution manager
service (nbpem) does the
following:
EMM & Master Server
bprd
1
2 )Gets the policy list from
bpdbm.
2
bpdbm
nbpem
2
3) Builds a work list of all
scheduled jobs.
6
nbjm
4 )Computes the due time for
each job.
5 )Sorts the work list in order of
due time.
6 ) Submits to nbjm all jobs that
are currently due.
Media Server
Client
7 ) Sets a wakeup timer for the
next due job.
8 ) When the job finishes, recomputes the due time of the
next job and repeats
at step 5.
ltid
14
Backup process
Next, the job manager service
(nbjm) does the following:
9) Issues a single request (with a
request ID) to nbrb, for all
resources required by a job. nbrb
gets the storage unit, tape drive,
and media id information from
nbemm and allocates client and
policy resources. nbrb returns to
nbjm an allocation sequence
containing one allocation for each
resource (each allocation contains
a unique ID). nbrb also returns
allocation data for the specific
resource type. nbrb also returns
the request ID along with the
allocations so that nbjm can
correlate the response with the
right request (and job).
EMM & Master Server
bprd
1
bpdbm
2
nbpem
2
6
nbjm
9
nbemm
9
Media Server
bpcd
nbrb
Client
10
10) nbjm starts the backup by
using the client daemon bpcd to
start the backup and restore
manager bpbrm.
bpbrm
ltid
14
Backup process
Next, the backup and restore
manager (bpbrm) does the
following:
EMM & Master Server
bprd
1
bpdbm
2
11) Starts bptm.
nbpem
2
6
12) Starts the actual backup (or
archive) by using the client
daemon bpcd to start the
backup and archive program
bpbkar on the client.
nbjm
9
nbemm
9
Media Server
bpcd
nbrb
Client
bpcd
10
bptm
ltid
11
bpbrm
bpbkar
14
Backup process
Next, the backup and archive
manager (bpbkar) does the
following:
EMM & Master Server
1
13) Sends information about files
within the image to bpbrm, which
directs the file information to the
NetBackup file database. The
information is sent by means of
bpdbm on the master server.
bpdbm
2
nbpem
2
6
nbjm
14) Transmits the backup image to
bptm. This is accomplished in one of
two ways :
If the media server is backing up
itself, bpbkar stores the image blockby-block in shared memory on the
media server. If the media server is
backing up a client on a different
host, the bptm process on the server
creates a child process of itself. The
child receives the image from the
client by means of socket
communications and then stores the
image block-by-block in shared
memory on the server.
bprd
9
nbemm
9
Media Server
bpcd
nbrb
Client
bpcd
10
bptm
ltid
11
bpbrm
13
14
bpbkar
Backup process
Next, the backup manager for tape or disk
does the following:
15) The bptm or bpdm process on the server
takes the image from shared memory and
directs it to the storage media.
■ If the storage media is tape, bptm
requests information for the first media and
drive to use, by exchanging information
with nbjm. bptm sends mount requests for
specific media and drives to the NetBackup
Device Manager (ltid), which causes the
media to be mounted on the appropriate
devices. If, during the backup, a tape span is
required, bptm again exchanges
information with nbjm to release the correct
tape and to get another one. nbjm
exchanges information with nbrbto
accomplish this.
■ For SharedDisk, AdvancedDisk, and
OpenStorage: bptm requests the volume
from nbjm, which passes the request to
nbemm to choose the volume and media
server to use. nbemmcalls nbrmms on the
media server that was chosen to mount the
volume. If a span is required, the same steps
are used to mount the volume as described
in the previous bullet.
■ For BasicDisk: bpdm writes the images to
the path configured in the disk storage unit.
The system disk manager controls the
actual writing of data.
In the case of an archive, bpbrm deletes the
files from the client disk after the files have
been successfully backed up.
EMM & Master Server
bprd
1
bpdbm
2
nbpem
2
6
nbjm
9
nbemm
9
Media Server
bpcd
nbrb
Client
bpcd
10
bptm
ltid
11
bpbrm
13
14
bpbkar
Backup process
Next, the job manager service
(nbjm) does the following:
EMM & Master Server
bprd
1
16) Receives completion status
of the job from bpbrm.
bpdbm
2
nbpem
2
6
17
17) Releases resources to nbrb
and returns status to nbpem.
nbjm
9
nbemm
9
Media Server
bpcd
nbrb
Client
bpcd
10
bptm
ltid
11
bpbrm
13
14
bpbkar

Veritas NetBackup™ Troubleshooting Guide
UNIX, Windows, Linux
Release 6.5