using tar with DAT drives

Simon Clayton Simon at
Tue Jun 5 12:55:09 BST 2001

Thanks for that - I think it might have highlighted a different problem.

I put a new tape in the drive and did mt status which tells me

Mode      Density              Blocksize      bpi      Compression
Current:  0x13:X3B5/88-185A    variable       61000    DCLZ
---------available modes---------
0:        0x13:X3B5/88-185A    variable       61000    DCLZ
1:        0x13:X3B5/88-185A    variable       61000    DCLZ
2:        0x13:X3B5/88-185A    variable       61000    DCLZ
3:        0x13:X3B5/88-185A    variable       61000    DCLZ
Current Driver State: at rest.
File Number: 0  Record Number: 0

If I'm reading this correctly, it is recognizing our DDS-3 drive
as a standard 2/4Gb DAT drive.  So, if all of the available modes
are standard DAT, how can I set it to be DDS-3?

I have noted Paul's comments about using dump -B to specify the
number of 1KB blocks but I would like to try and understand what
is happening with mt first - any ideas?


-----Original Message-----
From: freebsd-users-admin at
[mailto:freebsd-users-admin at]On Behalf Of Jose Marques
Sent: 01 June 2001 19:18
To: freebsd-users at
Subject: Re: using tar with DAT drives

On Thu, 31 May 2001, Simon Clayton wrote:

> So, the question is - can someone tell me the correct parameters or
> should I be using something else entirely like cpio?

Assuming you don't need to move the backups between different operating
systems then dump/restore would be better.

I have an HP 4GB DAT drive attached via a PC-Card SCSI controller and use
the following dump script

-8<- cut here ----
/usr/bin/mt rewind
/usr/bin/mt comp on
/usr/bin/mt status
/sbin/dump -0auf /dev/nrsa0 /
/usr/bin/mt status
/sbin/dump -0auf /dev/nrsa0 /usr
/usr/bin/mt status
/sbin/dump -0auf /dev/nrsa0 /var
/usr/bin/mt status
/usr/bin/mt offline
-8<- cut here ----

To restore I use:

mt fsf <dump-number>
restore -i

where <dump-number> is 1 for the second dump on the tape, 2 for the third
etc.  The -i option to restore invokes it in interactive mode which lets
you manually select which files to restore before starting the extraction.

Jose Marques

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