I know this is an old post, but just in case if anyone is looking for instructions on how to use "amrestore", refer the below steps.
Amrestore is a type of Bare Metal Recovery, which means it will restore all the data in the tape. So you will not have an option to select what you want to restore.
The first step is to Load the tape you want to restore from, in the tape drive. This can be done using the mtx command.
mtx -f /dev/sg10 load 4 0
In this case, sg10 is the changer library, 4 is the slot in which the tape is stored and 0 is the Tape drive number.
If you are using a single tape drive instead of a changer, you can directly proceed to the next step.
The next step is to run the amrestore command against the tape drive.
amrestore -r /dev/nst0 localhost (hostname is optional, nst0 stands for drive 0)
Running this command will give a file with .RAW format.
The filename will look something like this.
hostname.dle_name.date_time.file_number.RAW
Run the amrestore command once again on the .RAW file considering it as a holding file.
amrestore --holding hostname.dle_name.date_time.file_number.RAW
The output of this command will be a tar file (hostname.dle_name.date_time.file_number) which can be extracted to get the files restored
tar -xvf hostname.dle_name.date_time.file_number
Hope this helps.