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What happens during a live SQL Server backup

Created: 13 Sep 2012 • Updated: 17 Sep 2012 | 7 comments
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What happens during a live SQL Server backup ?

I just wanna know one or two liner steps in short.

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Marianne's picture

Please answer these questions:

Using which backup method?

What have you tried so far to find this answer?

If using the NBU agent - have you tried reading through chapter 1 of the NBU for SQL manual?
(I know that you have this manual because you posted questions before).

If you did, you would see this topic in the manual:
How does NetBackup for SQL Server back up a database?

Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and Windows
Handy NBU Links

NIKHIL2346565959's picture

SQL agent method.

I have read the manual.But it is not clear.

My doubt:When the SQL is not going down,then how the backup is consistent?

Marianne's picture

Please tell us what EXACTLY do you NOT understand about the second paragraph under this topic in the manual:

How does NetBackup for SQL Server back up a database?

If you don't understand the parts happening inside SQL, best to speak to your DBA.

Or just accept that the agent 'knows what to do'!

Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and Windows
Handy NBU Links

NIKHIL2346565959's picture

I just wanna know the short descrption of the process in easy language.

NIKHIL2346565959's picture
How does NetBackup for SQL Server back up a database?
From the NetBackup Microsoft SQL Client you can select the databases or the
database components that you want to back up. When you select an object for
backup, the GUI creates a batch file that contains a script. The SQL Server database
agent interprets this script. You can either execute the script immediately or save
it to run later. You can run a script later by including it in the backup selections
list of a backup policy.
When a backup script is executed, NetBackup for SQL Server does the following:
generates an SQL backup statement, logs into SQL Server, and delivers the SQL
statement to SQL Server through ODBC. Next, the database agent connects to SQL
Server through one or more VDI objects. One virtual device is created per backup
stripe. In addition, a VxBSA session is initiated for each stripe. These separate
sessions allow NetBackup to start a backup job for each stream that is generated
from SQL Server.
 
I have read this,but not able to find my answer.
Marianne's picture

Lets break that up into small pieces:

When a backup script is executed, NetBackup for SQL Server does the following:
 
  1. generates an SQL backup statement,
  2. logs into SQL Server, and
  3. delivers the SQL statement to SQL Server through ODBC.
  4. Next, the database agent connects to SQL Server through one or more VDI objects.
  5. One virtual device is created per backup stripe. In addition, a VxBSA session is initiated for each stripe.
 
These separate sessions allow NetBackup to start a backup job for each stream that is generated from SQL Server.
Which of these points do you NOT understand??
 
In all honesty, I am not a SQL dba, so I do not understand all of the SQL terminology either.
I don't need to understand.
 
The NBU developers worked with SQL developers to create a NBU plugin (dll) that KNOWS how to backup SQL online and pass the data to NBU.
 
That is all I need to know.

Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and Windows
Handy NBU Links

Will Restore's picture

In simple terms, NetBackup says to SQL server - give me some bits!  It's up to SQL server to provide the right bits in the correct order. NetBackup server functions as a scheduler (when to run) and media manager (where to put the bits).

Will Restore -- where there is a Will there is a way

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