Re: [gentoo-server] backup and crontab problem

[Rob Baxter]

Just to rule out the obvious here, does the user you're running the 
cronjob as have permissions to read /dev/nst0 ? I only ask because 
alsmot everything in /dev is owned by root. Could you post the cron line 
you're using as well? I realize you probably have to run the job as root 
to perform the load and rewind.
btw, tar -F implies -M, it doesn't need to be stated twice. (ps, i am 
fairly new to linux) =)

Rob

Frank Nørvig wrote:

> Hi there,
>
> I'm making a tape backup-script that looks like this:
>
> #!/usr/bin/perl -w
> WriteLog("Loading tape...");
>   $exec = `mtx -f /dev/sg0 first 2>&1`;
>   if ($exec) { WriteLog($exec); }
>
> WriteLog("Rewinding tape...");
>   $exec = `mt -f /dev/nst0 rewind 2>&1`;
>   if ($exec) { WriteLog($exec); }
>
> WriteLog("Backing up data...");
>   $exec = `tar -c -p --exclude-from=/opt/backup/backup-exclude.txt -M
> -F /opt/backup/changetape.pl -f /dev/nst0 /var/data 2>&1`;
>   if ($exec) { WriteLog($exec); }
>
> ... (rest is not important)
>
> When running this script from bash it works like a charm. All data
> from /var/data is backed up onto tape and everyone is happy.
>
> BUT when I put the script into my cronjob for automatic start in the
> night, it fails with following error:
>
> [2004-09-21 05:43:58] Loading tape...
> [2004-09-21 05:43:58] Rewinding tape...
> [2004-09-21 05:44:58] Backing up data...
> [2004-09-21 05:46:59] tar: /dev/nst0: Cannot open: Input/output error
> tar: Error is not recoverable: exiting now
>
> Why is this happening? And why is it only happening when run from the
> cronjob? Nothing else is run and no other program is using the
> tape-robot. The two tape-commands (mt and mtx) runs smoothly and loads
> +  rewinds the tape but the tar command fails everytime and has for
> over a month now. Every morning I have to run the script manually from
> bash and it runs perfectly then.
>
> I'm not new to Linux (or Gentoo) and has been installing and
> maintaining servers for more than 4 years now but this problem is a
> killer :(
>
> Frank Nørvig
>