Are you sure that the directory ./tmp and ./tmp/backup is writeable for user apache (use e.g filezilla to do a chmod 777 on the directories)?
It's not a permissions problem, because Opengoo creates the database backup and it writes almost a half of the backup file. I think it's a problem of the execution time, But I changed the php.ini to 800 (and to 1500) with no success.
After changing the values, I checked with a phpinfo that the value is updated in the system.
Any other value I could try to change?