cancel
Showing results for 
Search instead for 
Did you mean: 

How Differential Backup takes Reference

RajaV
Level 2

Hi,

Please help to clear my doubt on below query.

1. We triggered a full backup manually  for a server 'ClientA' on Monday morning and it completed on thursday morning successfully (Policy name: Fileserver_ClientA).

2. We triggered differential incremental backup manually for the same  server 'ClientA' on Saturday morning and it got completed within 2 hours. (Policy name : Fileserver_ClientA).

3. But, in between a scheduled full backup started automatically on Friday and completed on Monday for the same server 'ClientA' (Policy name : NewServer_ClientA).

Now, my question is...

 

The differential backup which was triggered on saturday will consider the changes happened after the first full backup (point 1) or the recent full backup (point 3). Here the client name is same for both policies, but policy name differes.

Please provide your comments.

 

Thanks & Regards,

 

Raja V

 

 

 

 

 

 

 

7 REPLIES 7

Genericus
Moderator
Moderator
   VIP   

The policy should have separate tracklogs.

You also want to check the client - they can be set to use attribute or timestamp, although this option may not be universally available. Not sure if that will impact the differential.

 

 

 

NetBackup 9.1.0.1 on Solaris 11, writing to Data Domain 9800 7.7.4.0
duplicating via SLP to LTO5 & LTO8 in SL8500 via ACSLS

PetrHanz
Level 4
Partner Accredited Certified

Hi RajaV

Differential backup job can use change/tracklog to previous "finnished"  full backup or another differential/cumulative backup, only. Change/tracklog cannot be used against second full backup running. 

   

   

 

Marianne
Moderator
Moderator
Partner    VIP    Accredited Certified

@RajaV

What is purpose of backing up the same data for the same client in 2 different policies?

Full and Incr schedules should be in the same policy.

Incr backup is based on previous backups within the same policy. 

What is purpose of backing up the same data for the same client in 2 different policies? - It's business requirement to complete the backup prior to an activity.

Full and Incr schedules should be in the same policy - Yes, both policies having Full and Incr schedules.

 

Incr backup is based on previous backups within the same policy. 

Now My Question : You mean to say differential backup will take the reference based on the policy or it will take the reference based on the client name. Please let me know if my question is confusing you. :) 

Hi,

So, you mean to say differential backup will take reference based on the previsouly ran full backup on same policy?

Please confirm. 

sdo
Moderator
Moderator
Partner    VIP    Certified

Yes, when a "diff" schedule is in a policy with any other full, cinc or diff schedule, then the next executing diff schedule will reference from any prior backup schedule, i.e. any of full, cinc, diff - i.e. whichever was most recent.

Here's what I think would have happened if this were a Windows file system backup.

As @Genericus mentioned, the incremental backup can choose files based on either the archive bit or the timestamp. In either case, your Saturday incremental backup would be based on the completed Monday-to-Thursday backup.

If you have configured to base incrementals based on the archive bit, the incomplete scheduled full backup didn't come into play, because it would not have cleared the archive bits until the end of the job, which wasn't until Monday.

If you have configured to base incrementals based on the file timestamps, then the catalog from the most recent complete backup was used. (You have given conflicting information about the policies. If the shceduled full backup was for a different policy, its timestamps wouldn't apply even if it had been complete.)