BackUp Exec 2012 - media sets/tape allocation

[Inspiration]

I have BE2012 with LTO6, just moved from 2010. Below is my configuration:

My Settings:

I have 3 servers to back up (partial selections).

Differential backup runs 4 times a week and full backup once a week.

Differential backup only uses 1 tape per day (all 3 servers backup into 1 tape - around 200 to 400GB a day). Full backup uses 4 tapes. (8 TB data in total)

To allow all 3 servers to backup into one tape, I set the Media Set to "Append to media, overwrite if no appendable media is available"

Overwrite protection is set for 13 days for differential, and 4 weeks for full backup.

What Happened:

Last week i ran the full backup as usual, I was rewriting onto 4 used tapes (overwrite protection date has passed)

But later I found the backup job to be pending and all 4 of my tapes were full. This is odd since my total data is still a little below 8TB, but available media storage was around 9TB (before the full backup. now it shows 0). And my total data backed up was only 3TB, so there is 5TB to go but my tapes were full.

My Theory:

Why did this happen? I suspect the below:

The backup data was appended to the tapes instead of overwriting them (eventhough overwrite protection period is over)

Eventhough the Media Set was "Append to media, overwrite if no appendable media is available", as soon as the data was appended onto the tape, a new overwrite protection was set - another 4 weeks, so that's why all tapes are full and wann't overwritten.

Is my theory correct? Does it work that way?

Is there a way to set it up so that it overwrites all the tapes when the protection is over and then append data. Not append data then attempt overwrite.

[Colin_Weaver]

What controls if a tape is appendable is the append period in conjuction with what the job is set to do at the start.

As such if your append period is still set to infinite and your job is still set to append at start then it will carry until it fills the tape.

[Inspiration]

Aha...yes currently it is Append infinetely

I will set the append for Differential to 1 day and Full for 3 days.

I think this will solve the problem I have. Let me try it out over the coming week.

[Inspiration]

The above works well, the problem is resolved.

But what will happen in the following scenario?

I have 800GB data to backup to a tape. The capacity of my tape is 2.2TB, but only 500GB of free space is available.

What will happen? Will it write 500GB then queue for a new tape or will it overwrite the tape, etc?

[pkh]

If you append to the tape then the job will write 500GB to the tape. It will then need an OVERWRITABLE tape to write the other 300GB. BE cannot spend too a second tape. For the second and subsequent tape, it needs overwritable tapes

[Inspiration]

You mean it will append only onto the first tape and not onto any subsequent tapes for that job?

Let's say my second tape has 400GB free space, and is overwrite protected, but append is allowed, and my job setting is "Append to media, overwrite if no appendable media is available". What will happen now?

I'm guessing the second tape cannot be used and the job will still be queued. Correct?

[pkh · Accepted solution]

Yes.  If this second tape cannot be used and your job will require an overwritable tape.  If there is no overwritable tape in the tape library, then there will be an alert asking you to import an overwritable tape for the job to continue.