Symantec Netbackup 6.5 backup process

1. Hernán J. Larrea

2.  Symantec Corporation has not participated
in the development of this document.
 All sources will be properly mentioned at
the end of the document.

3. 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 hjlarrea@hotmail.com.
Hernán J. Larrea

4. Things you need to know before thinking on the backup process.

5.  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.

6.  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

7. 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.

8. 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.

9. 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.

10.  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.

11. Backup process
After boot up:
EMM & Master Server bprd
1) A start-up script launches 1
bprd on the master server and
nbpem
ltid on the master server and all
media servers. All other
daemons and programs are
started as necessary, including
nbpem, nbjm, nbrb, and
nbemm.
Media Server Client
ltid 14

12. Backup process
The policy execution manager
service (nbpem) does the EMM & Master Server bprd
following:
1
2 )Gets the policy list from
bpdbm. 2 bpdbm 2 nbpem
3) Builds a work list of all 6
scheduled jobs.
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 Media Server
are currently due. Client
7 ) Sets a wakeup timer for the
next due job.
8 ) When the job finishes, re-
computes the due time of the
next job and repeats
at step 5. 14
ltid

13. Backup process
Next, the job manager service
(nbjm) does the following: EMM & Master Server bprd
9) Issues a single request (with a 1
request ID) to nbrb, for all
resources required by a job. nbrb 2 bpdbm 2 nbpem
gets the storage unit, tape
drive, and media id information 6
from nbemm and allocates client
and policy resources. nbrb returns nbjm
to nbjm an allocation sequence
containing one allocation for each
resource (each allocation contains 9 nbemm 9 nbrb
a unique ID). nbrb also returns
allocation data for the specific
resource type. nbrb also returns
the request ID along with the Media Server
allocations so that nbjm can Client
correlate the response with the bpcd
right request (and job).
10
10) nbjm starts the backup by
using the client daemon bpcd to bpbrm
start the backup and restore
manager bpbrm.
ltid 14

14. Backup process
Next, the backup and restore
manager (bpbrm) does the EMM & Master Server bprd
following: 1
2 bpdbm 2 nbpem
11) Starts bptm.
6
12) Starts the actual backup (or
nbjm
archive) by using the client
daemon bpcd to start the
9 nbemm 9 nbrb
backup and archive program
bpbkar on the client.
Media Server Client
bpcd
bpcd
10
bptm 11 bpbrm bpbkar
ltid 14

15. Backup process
Next, the backup and archive
manager (bpbkar) does the
following: EMM & Master Server bprd
1
13) Sends information about files
within the image to bpbrm, which
directs the file information to the 2 bpdbm 2 nbpem
NetBackup file database. The
information is sent by means of 6
bpdbm on the master server.
nbjm
14) Transmits the backup image to
bptm. This is accomplished in one of
two ways : 9 nbemm 9 nbrb
If the media server is backing up
itself, bpbkar stores the image block-
by-block in shared memory on the
media server. If the media server is Media Server Client
backing up a client on a different bpcd
host, the bptm process on the server bpcd
creates a child process of itself. The
child receives the image from the 10
client by means of socket
communications and then stores the bptm 11 bpbrm bpbkar
image block-by-block in shared 13
memory on the server.
ltid 14

16. 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
EMM & Master Server bprd
directs it to the storage media. 1
■ If the storage media is tape, bptm
requests information for the first media and 2 bpdbm 2 nbpem
drive to use, by exchanging information
with nbjm. bptm sends mount requests for
specific media and drives to the NetBackup 6
Device Manager (ltid), which causes the
media to be mounted on the appropriate nbjm
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 9 nbemm 9 nbrb
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 Media Server Client
server to use. nbemmcalls nbrmms on the bpcd
media server that was chosen to mount the
volume. If a span is required, the same steps bpcd
are used to mount the volume as described 10
in the previous bullet.
■ For BasicDisk: bpdm writes the images to
the path configured in the disk storage unit. bptm 11 bpbrm bpbkar
The system disk manager controls the 13
actual writing of data.
In the case of an archive, bpbrm deletes the ltid 14
files from the client disk after the files have
been successfully backed up.

17. Backup process
Next, the job manager service
(nbjm) does the following: EMM & Master Server bprd
1
16) Receives completion status
2 bpdbm 2 nbpem
of the job from bpbrm.
6
17
17) Releases resources to nbrb
nbjm
and returns status to nbpem.
9 nbemm 9 nbrb
Media Server Client
bpcd
bpcd
10
bptm 11 bpbrm bpbkar
13
ltid 14

18.  Veritas NetBackup™ Troubleshooting Guide
UNIX, Windows, Linux
Release 6.5