Backup and to-be backup tapes 1

[cavie]

Hi,

I have 2 set of tapes physically in the same library and in the same pool. One set of tapes contain the backup 1 month ago and had not expired. The other set of tapes is the current set of tapes that will be used for backup.

Purpose of putting in the first set of tapes is to do restoration of some files, in the backup windows of 2nd set of tapes.

In this situation,

1. How does netbackup decides which tapes to be used for current backup?

2. Would it append new files into the 1-month old tapes?

3. What factor does netbackup takes into consideration when choosing a tape for backup?


Thx.

 

[comtec17]

1. How does netbackup decides which tapes to be used for current backup? It is decided by the retention on the tape. If data is on them and you do not have the "use multiple retention periods" checked in the global attributes, it will only use the tape that has been used in the last 24 hours.

2. Would it append new files into the 1-month old tapes? Only if you have the "use multiple retention periods" checked in the global attributes.

3. What factor does netbackup takes into consideration when choosing a tape for backup? see answer 1

 

[cavie]

Thx, comtec17. Feel more assured now.

 

[PGPhantom]

What I usually do if I have tapes with data on them and I am running a restore ...
bpmedia -freeze -m <media ID>
Simply to avoid writing other data on those tapes.

 

[goace]

My Response to #1.

I don't use "Multiple Retention Periods" because I have heard it could become hard to manage the media. Tapes having all but one image expired are what I've heard is the challenge. Can anyone elaborate how you work around this? By company policy, I have to have multiple retentions periods of 1 yr, 5yr, up to 10 yrs. Weekly, I have to move data offsite all media tapes-guess what - they are not full.

I'd like to bring them back after being offsite for 1 month for appending the same 5 yr (example) retention period. So in this way I can keep appending until full; then I can keep that "full" tape offsite for 5 years and not worry about it for 5 year! Wow that would same me a lot of media mgmt time! But new scratch media is always allocated.

My Response to #2.

Can you set multiple retention periods for certain volume pools or policies(not global)?

Thank you.

 

[creakyjoe]

freezing the media, doh why didn't i ever think of that!. When i have to restore stuff i usually magic up a pool for all the forthcoming night's backups - allows the restores (9hour rman restores) to complete unmolested thru the night. Next time i think i'll look in to freezing the media instead

Rich

 

[lenski]

No multiple retention periods is a global setting.
NBU will as default use the last tape used for the next backup. It will also tend to use the same tape for the same backup. But trying to predict which one is going to be used is impossible because it takes so many factor in to considuration. I would say never use multipule retentions because you are right it causes so meny problems. You could end up with images which are 1 week and 10 years on the same tape.