This has been an on-going theme with this product for years. Not a criticism but an observation. I am a Commvault guy by trade. However, this piece of software, BE12, I have worked for in previous iterations years ago. My primary issue isn't necessarily the performance of the product. It works fine for my client. We backup about 7TB of data each week successfully.
However, I have read numerous posts about the dogon Append and I have to agree that it just does not work properly. I have configured AppAsuure, Commvault and other backup problems the exact same way in terms of retention and appendable and had no issues. I use the same setup with BE12 and it writes half the tape over the weekend and ejects it.
The answer in the posts always says to apply it to a media set. I did so. The media set I created has a 4 week retention with a 14 day append. No luck. Again, our backups are running fine but it makes no sense to half fill a 2.5TB piece of media only half way. Every weekend I have one last job waiting on media while BE12 refuses to utilize the available space.
Clearly I am missing something here. This isn't rocket science by any stretch. How do I address this issue so that BE12 functions properly?
When BE ejects a tape before you think that it should, what does it show for the append time in the properties of that cartridge? If it says "media full" (or something close to that, I don't remember BE 12 very much), then it is probably not a BE issue. I haven't had any trouble getting tapes to fill up over the years.
What kind of tape drive and what generation of media are you using? I just want to make sure there isn't confusion about native vs compressed capacity.
An append job, by definition, adds data to the remaining space, following on from presvious backup sets already on the tape. When the remianing space is smaller than the required space, it will use that space and then try to locate another tape (and if using a stand alone drive would eject the current tape) . You cannot go back and use the start of the same tape when this happns as that would need a complete overwrite of the tape (and if allowed would be a "snake swallowing its own tail" scenario)
To handle this you either need a library, OR you need to plan to periodically overwite the tapes at the start of one of your jobs during the week, instead of starting them all as overwrite (and yes you won't quite fill up your tapes when doing this) Note instead of starting a job as oberwrite you could reduce the Append Period of the tapes, this forcing an overwrite based on that timing as another way to achieve the same thing (although this would also need you to think about the overwrite protection period as well.)