Tape error messages

[Merit Europe]

Hi,

Let me try another question, the last one worked out well!

Before we run our backup, we check for the presence of a tape in the drive using the following command:
mt -t $DLT_TAPE rew

Now there are a couple of possible scenarios for the error output, does anyone have a script that catches these error messages ($?), and connects this to a human readable error message?

Thanks in advance,

Robert

[Sridhar Bhaskarla]

I would do

mt -t $DLT_TAPE rew 2>/tmp/errlog

if [ `wc -l` -ne 0 ]
then
#Here you can check for various errors and echo
#human readable. Else if you just want to
#print the error
cat /tmp/errlog
rm /tmp/errlog
fi

-Sri

[Merit Europe]

This is what i do at the moment. I was hoping someone had gathered these error messages for me, as they seem to be undocumented.

Can anyone give some more assistance?

[Stefan Farrelly]

The only error codes you can really get from using the mt command are 0 (success) or 1 (failure).

So;

mt -t /dev/rmt/0m rew
if [ $? -ne 0 ]
then
echo Either no tape in the drive or tape in use.
fi

The only question is how to test the tape in the drive is writeable ? Doing a rewind will not detect a non-writeable tape. Perhaps you would want to do a write test to the tape also to check its writeable ? (use something like echo > /dev/rmt/0m )

[Robin Wakefield]

Robert,

Try compiling the following. Basically the "mt_gstat" field is defined in /usr/include/sys/mtio.h and defines the state (including write protect status) of the tape/drive. You'll probably want to play with this to get what you want, but it's a start:

Rgds, Robin

======================================
#include
#include
#include
#include
#include
#include

int main(int argc,char *argv[])
{
/* int argc;
char *argv[]; */
struct mtget mtget;
struct mtop mtop;
char *dev="/dev/rmt/3hcn";
int fd;
if (argc > 2)
{
fprintf(stderr, "Usage: %s \n", argv[0]);
exit(1);
}
if (argc == 2)
dev=argv[1];
/* open the device */
if ((fd=open(dev,O_RDWR))<0)
{
/* printf("\nfd ERROR = %d\n",errno); */
perror("open failed");
exit(errno);
}

if ((ioctl(fd,MTIOCGET,&mtget))<0)
{
perror("ioctl(MTIOCGET) failed");
exit(errno);
}
printf("\nmt_gstat = %x\n",mtget.mt_gstat);
/* else
{
printf("\nmt_gstat = %x\n",mtget.mt_gstat);
if (GMT_BOT(mtget.mt_gstat))
printf("BOT\n");
else if (GMT_EOT(mtget.mt_gstat))
printf("EOT\n");
} */
exit(0) ;
}
==========================================