Because there are often problems with certain tape drives or systems when end of tape conditions occur, btape has a special command fill that causes it to write random data to a tape until the tape fills. It then writes at least one more Bacula block to a second tape. Finally, it reads back both tapes to ensure that the data has been written in a way that Bacula can recover it. Note, there is also a single tape option as noted below, which you should use rather than the two tape test. See below for more details.
This can be an extremely time consuming process (here it is about 6 hours) to fill a full tape. Note, that btape writes random data to the tape when it is filling it. This has two consequences: 1. it takes a bit longer to generate the data, especially on slow CPUs. 2. the total amount of data is approximately the real physical capacity of your tape, regardless of whether or not the tape drive compression is on or off. This is because random data does not compress very much.
To begin this test, you enter the fill command and follow the instructions. There are two options: the simple single tape option and the multiple tape option. Please use only the simple single tape option because the multiple tape option still doesn't work totally correctly. If the single tape option does not succeed, you should correct the problem before using Bacula.
: explain how to get rid of the test data in order to make regular use in pools after that (otherwise 'Cannot label Volume because it is already labeled: “TestVolume1”' appears)