What do I need to do next to troubleshoot a misconfiguration or hardware 
problem.  If I am using a bad installation, I am not averse to wiping the 
machine clean of Amanda and re-installing from source..

>>> "Dustin J. Mitchell" <dustin AT zmanda DOT com> 07/24/08 8:02 AM >>>
On Thu, Jul 24, 2008 at 2:01 AM, Doyle Collings <dcollings AT loganutah DOT 
org> wrote:
> I am only backing up one file, an iso image, which is about 2.6 gigabytes in 
> size.  Maybe that is why I get an error after 2.5 gigs. The tapes The LTO4 
> tape drive I am using is has a capacity of 800 gigabytes uncompressed and 1.6 
> terabytes compressed.  I have tarred to that drive at speeds of 5.5 gigabtyes 
> a minute.  I don't have a holding disk configured because my experience with 
> tar led me to believe that my tape could handle the speed of my fastest 
> source drive. I figured the holding disk  would only slow me down. I have 
> corresponded with others that use LTO3 drives that are having faster speed 
> than me. I don't know if any of them are using gnu-tar. One who has been 
> using Amanda since the early Ninetees is definitley still using dump.  Is my 
> holding disk logic flawed?  I am only backing up from one local fibre 
> attached SAN

Well, a few things, in order:

 1. You have some kind of misconfiguration or hardware problems if
your taper is erroring out before the tape is full.  First priority is
to fix that.

 2. Backing up a single file isn't really a good use of Amanda, and
*definitely* is a waste of 797.4GB of tape space.  I assume this is a
"test" arrangement for Amanda, and that you'll be backing up more data
later?  If so, you will get more realistic results from a more
realistic test.

 3. Your measurements comparing Amanda to tar are flawed.  If you can
successfully write a larger dump file (tens of GB) to tape, we can
look at the tape write rate and determine whether and by how much
Amanda's tape writes are slower than tar.

 4. You can definitely optimize Amanda for a better tape write speed.
Adding a holding disk would be one way to do that.

Dustin

-- 
Storage Software Engineer
http://www.zmanda.com