Backup retention period questions

[Junz]

I have a question regarding the backup retention period and restoration. Before i go to my question, please help me to elaborate the scenario that i give below. Let's say my daily incremental backup set to 2 weeks and the weekly full backup set to 3 months.

 Daily backup:
--------------------
 1 Oct 18 ---- retention 2 weeks -----> 15 Oct 18
 2 Oct 18 ---- retention 2 weeks -----> 16 Oct 18
 3 Oct 18 ---- retention 2 weeks -----> 17 Oct 18
 4 Oct 18 ---- retention 2 weeks -----> 18 Oct 18
 5 Oct 18 ---- retention 2 weeks -----> 19 Oct 18
 6 Oct 18 ---- retention 3 months ----> 6 Jan 19

One day on 27 Oct 18, a user report that his file was missing after 2 Oct 18 and request to restore it. Which mean his file still available before 2 Oct or 1 Oct, but the 1 Oct 18 daily backup image already expired. Is the backup engineer still able to find the missing file and restore it?

What my question here is when 6 Oct 18 start a full backup, will it backup the 1 Oct missing file also? or it will only backup the latest state like 5 Oct.

Hope anyone here can understand my question.

Thank you.

[RiaanBadenhorst]

You said "What my question here is when 6 Oct 18 start a full backup, will it backup the 1 Oct missing file also? or it will only backup the latest state like 5 Oct."

Its not possible to backup a file that has been deleted. 

You said the file "Which mean his file still available before 2 Oct or 1 Oct," which means the file is not there any more on 6 October. It can therefore not be backed up. 

But what neglect to mention in your example is the backup on 30 September, which would be a full and would have the file (if it existed) as is on the 30 September. This might or might not be helpful to the user.

[Junz]

Hi Riaan,

Thanks for your reply. But what if he only created the file on 1 Oct not before 30 Sep, then on 3 Oct the file was disappeared "myteriously". Plus the daily backup image on 1 Oct was expired also. Is it still possible to recover it with full backup?

Thank you.

[RiaanBadenhorst]

No, since it was not backed up on the 6th by the 3 month retention policy and the 2 week retention has expired.

[Marianne]

If you were doing Synthetic Full backups, the full backup would've been built from the last full + incremental backups.

Regular Full backup simply backs up everything that exists on the client at the time of backup. 

See NBU Admin Guide: 
https://www.veritas.com/support/en_US/doc/18716246-126559472-0/v44157639-126559472

[Junz]

I see. Now I understand the theory. Why am I asking for this question because I want to know what actually is the best practices for the backup retention period (incr and full).

What my concern here is my current retention period for daily incr backup is 3 months, weekly full backup is 6 months and monthly full is 2 years. As now we are lack of tapes to use for backup, so I want to adjust the retention period. And i feel the daily retention 3 months was too long period. Initially, I was planned to reduce it to 1 month. But to adjust it I also need to understand what is the impact.

Thank you.

[Genericus]

This is where you need to interact with the users when you are defining your retentions.

I had the same situation, except my fulls were monthly, and the application group was only keeping files for 10 days.

The full backup only had the last 10 days to restore. I had to convince them to keep 45 days on disk to avoid  this issue.

Recently we realized we were using NetBackup as an archiving tool, and doing entirely too many restores. We met with our application groups and requested they define their retention policies - how long active, how long on disk, etc. NetBackup is really for recovering files, not being the long term storage.

Be aware of what you take responsibility for!

[Genericus · Accepted solution]

I highly recommend that every backup admin create a retention document that lists out what you backup, how often, and how long it is kept. This will be all you need to provide for security audits. This is your CYA when someone asks for a restore out of bounds.   So many times I have simply forwarded my doc when requested how longs backups are kept.

Of course, you also need to update it and ensure it is accurate. 

It is also leverage to get the customer groups to generate theirs as well...

[Junz]

Thank you for your suggestion. This is what i need. Because I really donno what to do to reduce the usage in tape since the tapes were insufficient now. Stock up the tapes can be the solution, but i review the backup size and backup times really used a lot. I think i need to raise up to my boss and redefine again the retention period.