Overwrite Protection - question

Sounds like the job has filled the tape up, and has tried to reload the same tape to continue the job

This is a stand-alone drive, not a loader/library, correct?

Umm did the job fill the tape and then find it was overwritable so try and use it again.

Bascially when a tape is filled during a job, the job searches for an overwriteable media to continue the job, looks to me like it is finding that the original media is overwriteable but then protecting you from something dangerous by detecting that the media was used by the same job.

Would recommend setting your overwrite protection to at least 1 day and then make sure another piece of overwriteable media is available (if tape - a B2D will create another media anyway as long as it does not find something that is overwritable.)

How can I check to see if the tape is full?

it the job starts writing and then after a while pops up this error, the tape is full

 Look at tape details in media section of admin console

But bear in mind your problem is kind of that your tape fills up during one of the jobs and you have got 0 overwrite protection it is the combination of the two factors that is likely to cause the problem.

Rather more concerning though is if you have 0 day overwrite protection how are you stopping your full backup from being overwritten - bearing in mind that to recover a complete set of files you would need the full and one of the differential backups. 

This is an older version of Backu Exec - v8.6
I don't see a place (see screen shot below) to set overwrite days.
What should I choose, the middle option - partial?

I can do "properties" on a tape in the Media section, and click on Statistics, but I don't think that is what's on the tape.  Bytes written is 269 Gb, and this is a DDS4 20 gb tape.

 Sorry not familiar with 8.6 - but the later versions use a media set to control the overwrite properties that work with similar settings to those shown in your screenshot. As such if 8.6 also uses media sets you need to look at these properties.

However the newer versions do have that none setting - which is a really bad option to choose for not accidentally overwriting a critical tape. At very least would set that to partial.

v8.6 is similar

From the Media Tab, right click the media set\Properties

And I completely agree that the Global media management option of protection NONE is very poor choice (or  a media set OPP of none for that matter)

The backup failed again last night.  But, it does backup data.  I come in, in the morning, and there's an alert that "there's no appendable media, Please insert media '4MM000001' into the drive"  I click on Ok. and the job ends.  Although, the time shown in BE shows it ended last night.
This is what I don't understand:
- if the tape was full, how could it backup any data?  It backed up 9gb
- if I look at previous jobs that ran, it has successfully run, and when it does, it backs up about 10gb.  I'm surprised it's backing up anything, if the tape is supposedly full.

A big part of the problem is, this version is so old.  I not only don't see a place to check if the tape is full, I also don't see a place to view the job schedule.

The tape was not 100% full - it had space for 9GB and then asked for another tape.

Would suggest you look at the Managing Media section in the Admin Guide
http://support.veritas.com/docs/240870