Command to get tape capacity status?

[Scott R. Ehrlich]

Hello to all:

I have an Overland tape library connected, via SCSI card, to an out-of-box, 
full install of CentOS 5 install on an old PC.

I have a script that uses tar to archive data to tape and mtx to change tapes. 
What I don't know, if possible, is to obtain the status of how much tape is 
left in the drive.   If I get a write failure, I'd like to know if the tape is 
bad or has run out of space.

I know of bacula, amanda, and other backup methods, but I prefer to use the 
simplest options possible, mainly because if a hard drive failure occurs, which 
has happened at the last minute, I can take the original CentOS 5 media from 
CD, install it, and get back up and running in no time.

So, any way to inquire remaining tape status and [estimated] capacity?

Thanks.

Scott