TAR Fail

[Vogra]

I use TAR to make a backup from my system. Last nigth it was fail and show the following message: "Can't open /dev/tty to prompt for more media.". If I try to start again, the tar begin with no problem, but it's second occurency of this problem.
thanx in advance.

[Ravi_8]

Hi, claudio

check the tape size u r using and size of file that u r trying to backup. by looking at the error it looks that file size exceeding the tape size.

[Vincenzo Restuccia]

/dev/tty is a device file for a
terminal, probably the console terminal in your case.

[Vogra]

- Hi Ravi.
the Unit - DLT4000 - uses a 40 Gb tape and it's error occur at begining of copy.

- Hi Vincenzo.
really /dev/tty im my console, but this routine run with Cron and a Console is not in use when the error occur.

[Vincenzo Restuccia]

The way I see this is the tape is getting full, and can not find the
console to prompt for another tape.

[Ravi_8]

Hi,
since the error occur at the begining it is sure that the file to be backed up is larger than the tape size. because the tar checks the size of the file with that of tape, if it is less or equal then tar proceeds else tar fails.

[Bill McNAMARA_1]

ioscan -fnkCtape

locate the device file for your DDS drive

then
tar -cvf /dev/rmt/2m
or whatever the device file returned from ioscan is.

A tty device file is for a text terminal or
serial line port multiplexer not for magnetic
tape drives.

Later,
Bill

[Vogra]

Ravi,
although your mind is correct, the file that TAR is check at begining is too small - and I don't have any file greater than my space in tape. But... I say but, although I'm using
tar -cvf /dev/rmt/0m , I was deep in thought: it's possible the tape is not in the begining when the tar start? Than the tape is going to the end and than I wouldn't have space to save my files? It's possible ?

[Darrell Allen]

Hi,

Since you ran the tar from cron there was no controlling terminal for tar to post a mount request when it wanted another tape - hence the can't open /dev/tty message and tar gives up.

Now, why did tar want another tape? Perhaps the one you used was bad or write protected. Have you tried another tape? Was the same tape being used both times tar failed?

Hope this helps,

Darrell

[Ravi_8]

Hi,

check with Darrel points, doubt on the tape.
whenever u tar -cvf it is archieved on the begining of the tape not at the end, to append to the tape we'll use tar -rvf

[Volker Borowski]

Claudio,

the DLT4000 has a capacity of 20GB and the 40GB is the capacity with an average compression of 2:1.
If you have many compressed files on this system, you might not be able to backup more than 25-30GB, because you will not reach this 2:1 compressratio.
It is most likely, that the device is full.

You can check the following to be sure:

tar cvf - list_of_file | dd bs=1k of=/dev/null

with the output of how many blocks dd did transfer, you should be able to estimate, how close you are to the end of tape.
Compare this with

tar cvf - list_of_file | compress | dd bs=1k of=/dev/null

And check this result against the uncompressed limit of 20GB.

Both commands may take a while to finish.

Hope this helps
Volker

[Carlos Fernandez Riera]

That message tell you that is not more media. I guess the tape is not at Begining when you start tar.