Error - Not appendable (Media full)

[Dan-E]

I am using Backup Exec 2012, latest updates on Windows server 2008. I am doing nightly backups on a rotated set of 10 tapes (1 per business day). I am not concerned with overwrite protection whatsoever, all I want is for the backups to be written to tape - appended if there is enough space, or if not, to overwrite the old data, which will always be 2 weeks old due to the time it takes for a full rotation (1 fortnight).

However, I am finding that when my backup jobs get a tape that is full or close to full, instead of overwriting the old data my backups are spontaneously failing with the errors:

Described against the tape in the Media area:

• Overwrite Protection Period: Overwriteable
• Append Period: Not appendable (Media full) 

Described in the job log against the failed job:

No appendable media could be mounted.

Switching to overwrite operation on scratch media.

When these errors occur, the job ejects the tape typically in the middle of the night and halts the job. Here are my relevant settings:

Media set properties:

• Overwrite protection period: 1 Hour
• Append period: None

Other:

• Settings > Storage > Media overwrite protection level: None + No prompting
• Settings > Storage > Media overwrite options: Overwrite recyclable media ...

This is baffling, because according to my settings, it should overwrite recyclable media, not scratch media, but you can see in the job failure log that when it decides appending is off the table it goes straight for scratch media. Additionally, there is effectively no overwrite protection whatsoever, and even if there was, the old data on this tape is a month old, so I can't see how this is an OPP related error.

Also, I have 3 different media sets associated with different tape drives, and they are all suffering from this issue. Also I should note that I am new to this position and while I was being trained up by the prior guys, this issue didn't seem to be happening, so I'm not certain but perhaps they were manually erasing the tapes when they got full, but theoretically that shouldn't be neccessary anyway.

Anybody got any clues what's going on?

[Dan-E]

Thanks Colin,

As I eventually concluded, I think the root of this particular problem was the "swallow your own tail" scenario. It makes sense that BE would protect against this, and I initially didn't realise the nature of LTFS means it is unable to overwrite data in a linear fashion without losing all the rest of the data, thus I wasn't aware that the looping append/overwrite nature of my backups is not possible with LTFS on a single LTO tape.

The more you know! 

On a side note, I am still having eject issues (though much less frequently), but I believe these are a separate issue unrelated to this one, and if need be I'll raise them in a new thread.

Thanks everyone for your help!!