Backup

[Amran Bin Md Said]

I am running a backup of database file to tape using the crontab every night. The command I'm using is tar. What is the problem is that, the backup sometimes ended successfully and sometimes not. It is intermittent. I can say, for the first 3 days it is not successful and the next day it is successful. The error that I am getting is 'can't open /dev/tty to prompt for more media'. Please help.

[Andreas Voss]

Hi,

the problem you have is that the amount of
data you want to backup exceeds sometimes the capacity of your tape. When this happens the tar commands prompts for an additional tape. Since you are running the tar job by cron there is no dialog device to see for the tar command and it exits.

So the only way to run the tar by cron successfully you must reduce your backup data to fit the capacity of your tape.

best regards

Andrew

[Venu_2]

Hi,

It's clear that the amount of data is more than the tape capacity.

Are you appending the tape? if so try using fresh tape as the old tapes might be full.

Plan your files to be backed up to fit in one tape, else you can enable compression. I don't really suggest for comp'n , better way is to upgrade your drive.


venu

[Carlos Fernandez Riera]

It's dificult to respond, because you dont say wich drive and tapes are you using.

So, only some ideas:

If you are using DAT tapes (DDS1 or DDS2) after about of 50 passes these tape loss capacity due to degradation of medium. Use new tapes.

tar, by default, write blocks of 10k and newer tape needs great amount of data to be busy all time; if not driver mechanism must stop and start (streaming) again with loss of performance and tape space. tar accept -b option , so you can increase then up 32k. You can try with pax too.

Perhaps you are ussing 'incorrect' tapes. I mean that a DDS2 drive can write DDS1 tapes(90m). Use recommended tape length.

Carlos

[Amran Bin Md Said]

Thank you all for the suggestions. It gives me some sort of direction to solve this problem.