determing block size of DDS tapes

[mpaschali]

Hi all,

I need to copy the contents from a DDS1 (2.6GB) to a DDS3 as the DAT40 drive we have doesn't read the DDS1 tape.

I was going to use the "dd" command to copy the contents onto disk then onto the DDS3 tape, however, I am unsure how to get the block size off the DDS1 tape.

Any suggestions? Or is there a quicker way to do this?

Thanks

Maria

[Michael Tully]

If you have time and of course the disk space I would copy the contents of the DDS1 tape to a file system and create a new tape onto your DDS3. These days 2.6Gb is not a lot of data.

[Ravi_8]

hi,
the dds1 7 dds3 tapes uses different block sizes(i'm not sure about block sizes), but copying from one to one directly may cause problem. it is better to copy to system from dds1 then to dds3 tape

[Volker Borowski]

Hi,
it would help, if you know what is on the tape.
I.e. the command, that was used to create the tape. Like a 32k cpio-archive created with:

cpio -ovC 32768 > /dev/rmt...

If it is a standard tool (tar, cpio - format) I would go first by blocksize 512 or 5120.

If another blocksize was given, when the tape was created it will be a little bit hunting.

I would not go by reading with a physical value like the max_blocksize of the device.
If the blocksizes do not match, you may not get the entire content of the tape.

If it is a standard cpio format (5120 byte bs),
you could read

dd if=/dev/rmt/dds1 of=/somwhere/TAPE bs=5120
and write
dd if=/somwhere/TAPE of=/dev/rmt/dds3 bs=5120

After this your tape should be readable with the corresponding restore-command that created the DDS1 tape.

Volker

[Carlos Fernandez Riera]

Dont worry about physical blocks.

The question is what command had be used to write tape. Cpio use to write in 5k block size, tar in 10k, and dd is user configurable ( 512b by default).

So:

dd if=/dev/rmt/DDS1 of=/dev/rmt/DDS3 bs=xxxxk will duplicate your tape sucessfuly.
If tape was wrote with more than one command ( tar /tmp; tar /var ...) run a dd for each one.