Problems with ontape when using tapes taken to/from other systems.

Example ontape error :-

  $ ontape -r                                    
 Please mount tape 1 on /dev/st0 and press Return to continue ...      
                                                                       
 Physical restore failed - function read archive backup failed code -1 errno 5  
 Program over.        

Example 'dd' error :-

  $ dd if=/dev/st0 of=/dev/null bs=2k count=100
 dd: opening `/dev/st0': Permission denied

 $ su -                                    
 Password:                                                          
 # dd if=/dev/st0 of=/dev/null bs=2k count=100
 dd: reading `/dev/st0': Input/output error                          
 0+0 records in                                                      
 0+0 records out                                                    
 0 bytes (0 B) copied, 3.17481 seconds, 0.0 kB/s      

There are a number of reasons you might get this error, including a bad tape. You should also consider checking the block size settings for the source and target tape drivers are compatible.

You have checked and confirmed the Informix ONCONFIG values TAPESIZE and TAPEBLK are identical on both the source and target instances. Next, check the block size settings for the tape drivers either match, or the target is set to 0 (variable length blocks).

Check both the source and target system by inserting a tape, and typing the following command :-

  # mt -f /dev/st0 status

The output may look like this :-

  # mt -f /dev/st0 status
  SCSI 2 tape drive:
  File number=0, block number=0, partition=0.
  Tape block size 512 bytes. Density code 0x0 (default).
  Soft error count since last status=0
  General status bits on (50000):
  DR_OPEN IM_REP_EN

If the 'Tape block size' values are different on each system, then you can either set them to the same value or make the target accept variable length blocks (0).

Example of setting the tape driver to variable length blocks :-

  # mt -f /dev/st0 setblk 0

The 'Tape block size' will now show up as 0 when the status command is run. This allows the drive to read tapes written on other machines.