'en cola'

Proceeding with translation provided by Google...

LTO 3 tapes are of capactiy 400GB in native mode and 800GB in compressed mode. This doesn't mean an LTO tape can hold 800GB of data always, but it can hold a minimum of 400GB (without considering overheads). If the data that is being backedup is highly compressible then you can see more than 800GB of data being save on LTO 3 tape. 

Infinite-Appendable: This is media set property, which will let the data to be appended to tape untill it becomes full.

Not Appendable-Media Full: This is current state of media. As it is full, no data can be appended to it.

As soon as the media becomes full, there should be an alert asking you to insert an overwritable media into the drive and respond to it, incase if you do not have any recyclable/Scratch media available in the library. Please check in Alerts tab.

Thanks, but i've checked the alerts tab and ther's not new alerts. The only change i can see is that in task status is 'queued'

On the other hand, on tapes i've been using, with the same data to be backed up , untill 700 Gb were hold , so I can understand why now only can hold 400Gb.

Finally, to allow to append new data, I supose the only task to do is to erase old data. My I need to change label , nor import the tape?

...check for Hard Write errors on the tapes in question, especially if they held more data on them. Excessive write errors on the tape can indicate that they are faulty.

Also make sure you are using the Symantec drivers for the tape drive, and not the manufacturer's drivers, and that compression is still turned on.

Do you have compression enabled in the backup job? 

According to the media set configuration (With Infinite Overwrite Protection and Infinite Append period), Backup Exec never re-uses the media automatically. Is that what you intended to have in-place?

Finally, to allow to append new data, I supose the only task to do is to erase old data. My I need to change label , nor import the tape?

The backup is in middle and if you erase the media that is used with this backup, no use even if you get BE to append the remaining data. You can erase the tapes that are holding data that is nomore required. once that tape is Scratch media, BE should be continuing backup to it.

Recheck your media set configurations against retention requirements.

Sorry Kiran, but how do you get more than 2:1 compression on a tape? I've never heard of this from any vendor, considering their best for the LTO format is 2:1...

An LTO3 tape is 400GB native, and 800GB 2:1 compressed...no way to get more than 800GB on that tape, no matter how compressible the data...

I have seen this in so many environments i am supporting with different backup applications even with BE and NBU. Not just once, number of times. I even remembering other users (i think andy) in forum referring to that very recently. Let me check if i can post the link here.

Edit: Infront of NMC.. Posting a SS of media details... LTO5 medias

I'd be keen to see the compression stats...

2:1 is the average compression provided by the common compression algorithms used by hardware and software vendors as a guide and for their quoted figures. If you have a subset of data that is highly compressible that is not mixed up with data that is either not compressible or only provides very low compression rates then you can get higher than 2:1. However is most corporate environments the typical data set would compress between about 1.5:1 and 2:1

.. No hard write errors are reported , and only 26 write errors reported.

Now i'm using manufacturer's drive. In unit properties, configuration, compression is activated.

Could you please tell me where I can find symantec drivers ??

Thanks