tape content unreadable

[tedans]

I have a 4mm tape media where I placed backup files from a server using the command:

# tar -cvf/dev/rmt0 [files]

The content of the tape can be read on the same server where I backed up my files and on other servers however it can't be read/restored on other servers. I tried changing the the characteristics of the tape device but still failed to read the content of the tape on such servers. How can this be? Below are the settings of the tape device

Change / Show Characteristics of a Tape Drive

Type or select values in entry fields.
Press Enter AFTER making all desired changes.

[TOP] [Entry Fields]
Tape Drive rmt0
Tape Drive type ost
Tape Drive interface scsi
Description Other SCSI Tape Drive
Status Available
Location 04-C0-00-2,0
Parent adapter scsi0
Connection address 2,0
BLOCK size (0=variable length) [0] +#
Use DEVICE BUFFERS during writes yes +
RETURN error on tape change or reset no +
Use EXTENDED file marks yes +
RESERVE/RELEASE support no +
BLOCK SIZE for variable length support [0]
DENSITY setting #1 [0] +#
DENSITY setting #2 [0] +#
Set delay after a FAILED command [45] +#
Set timeout for the READ or WRITE command [144]

 

[bjverzal]

What are the settings on the other servers ? The most likely cause of this is a difference in the "block_size" parameter.

Bill.

 

[tedans]

can all 4mm tape drives read tape media used on other servers? I've tried changing the tape drive characteristics with the same type as that of the other servers including the block size but still failed to read the media.

 

[bjverzal]

Are the tape drives the same model ?

Bill.

 

[gheist]

check your drive configurations:

> lscfg -vpl rmt0
> mt -f rmt0 status

check if tape is readable on another machine by dd
> dd if=/dev/rmt0 of=/tmp/whatever bs=1
note the blocksize of one byte makes it very slow

try a test - if the tape written on other machine reads on first one

- write down your rmt0 parameters and remove it from device list and redetect so it comes up with its default settings

- maybe a fixed blocksize of 512,1024 or 2048 may help

- there may be problems with file marks especialy if they are not recognized by another tape