I have one server with be 12.5 (yes i know, is very old).
From 3 weeks i have a problem with a tape lto 3 (400gb) on hp ultrium (Its works perfecrly since 2007)
Only one tape of set fails: the error is "tape full" (it fails around 70%).
This is not possibile becouse the selection list of the job its only 250gb, and tape can backup 400gb compressed.
I replaced the tape with two new differents tapes (always lto3), but the problem perstists
Getting the advertised compressed capacity totally depends upon your data. So, in the real world, you may get anywhere from 200GB (native) to 400GB (advertised compression) per LTO2 tape. You mention an LTO3 tape drive, but your mention of "400 GB compressed" implies LTO2 media cartridges. Are you using LTO3 tapes? LTO3 = 400 GB native and 800 GB (advertised compressed)
Once the media types and compression is clarified, yes, it is possible that your tape drive has failed and can no longer write as much to a tape as it used to. Please see http://www.veritas.com/docs/000017157