Verifying integrity of Backup Tapes

Rick Duvall rduvall at
Sat Nov 1 00:31:02 PST 2003

I was doing incrementals, and since my amverify failed on one of my tapes, I
found that doing incrementals in my case is a bad idea if I can fit a full
backup of all my data onto one tape.  Now I am doing a level 0 on every run.
Amverify get's to about the 6th filesystem I am dumping to tape and gives me
an Input/output error.  I know it's not the end of the tape, otherwise
amdump would say so.

FYI:  These are travan 10/20 tapes.  I know, not the best choice.  I am
trying to convince my boss to replace it with a DDS4 drive, as the DDS4
tapes are less expensive.  These are $40 a piece, whereas the DDS4's are $13
a piece and hold twice as much data.


Rick Duvall
----- Original Message ----- 
From: "Technical Director" <trodat at>
To: "Rick Duvall" <rduvall at>
Cc: <freebsd-questions at>
Sent: Friday, October 31, 2003 9:03 PM
Subject: Re: Verifying integrity of Backup Tapes

> Rick,
> I'm not to sure of a best method for checking the tapes, I might tar'ing a
> massive file to the tape and then back to see if it is working.
> Unfortunately during the use of your backup schema the tapes have to
> degrade. If it's a DLT400 tape or even a DDS# series I can see the need to
> hang on to them for some time to insure the cost of the media was
> repaid. Might it be best though to question the integrity of using a media
> that may have reached it's usable lifespan?
> As well depending on your method of backup, say full, 1/4, 1/2, 1/4, 1/8,
> etc. one tape that has a problem with the data on it will throw the entire
> sequence of backups. And if you have full backups, skipping the
> incremental, you might save yourself the hassle of a wrecked sequence of
> incrementals, yet the entire concept of backup is lost with bad media.
> I'm just trying to give you some ideas on how to go from here, not trying
> to critisize you on something you probably are already thinking.
> R.
> On Fri, 31 Oct 2003, Rick Duvall wrote:
> > I have some backup tapes that I have been using each once per week for
> > 8 months.  I am getting errors when running amverify on a couple of
> > To be sure that my tapes are still good and not just the system giving
> > fits, it would be nice if I could run a program that would write bits to
> > tape in question and try to read them back, telling me which blocks on
> > tape are bad.  Is there such a tool that does this?  I guess it would be
> > kind of like a scandisk is to a DOS Floppy as what I am talking about is
> > a Unix Tape.
> >
> > Sincerely,
> >
> > Rick Duvall
> > Online Highways
> > System Administrator
> > (541) 997-8401 x 111
> >
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