[flexbackup-help] Determining Tape Drive Size

[Dan <dr...@dt...>]

I am writing some [minimal] oss software, after 5 years of just using it.

Background:

Simplified "unmanaged" distributions like e-smith / SME server 
(www.contribs.org) are not supposed to require a full-time admin.

Once setup by someone competent, they require nil maintenance unless 
something breaks.

I am unsatisfied with the backup solutions available.  Hard drives are 
now large, but large tape drives are expensive, especially for the s in SME.

I like the DDS2 tape drives that are almost free and plentiful around 
here, as are tapes used once only.


Problem:

The system does not provide effectively for incremental backups, and in 
any case that would require sensible tape management.  I want a full 
nightly backup on a new tape each night.  However, the data set is too 
large for the tape, and restoring can be complex.

Solution:

1) Get flexbackup to prompt for the next tape via email.  I couldn't 
figure this out, and in a full backup every 24 hours you may find a tape 
drive which is permanently in use.

2) Split the backup into five flexbackup sets, named by the days of the 
week.  Call flexbackup with date +%A as the set name.  Define the sets, 
each small enough to fit on a certain part of the drive.  Automate this 
using bash scripts and du, and a script to detect when the sets are too 
large to fit on the tape

Question:

   How can I determine the capacity of a tape in a generic fashion?  I 
want this to run on any e-smith machine.