tape (sa0) on sparc64 ?

[Bob Bishop]

Hi,

On 17 May 2013, at 01:30, Greg 'groggy' Lehey wrote:
> On Thursday, 16 May 2013 at 19:56:14 -0400, Zaphod Beeblebrox wrote:
>> On Thu, May 16, 2013 at 5:08 PM, Bob Bishop <rb at gid.co.uk> wrote:
>>> On 16 May 2013, at 21:51, Zaphod Beeblebrox wrote:
>>> 
>>>> I have to retrieve some very old backups.  They were made on FreeBSD and
>>>> are on tape... specifically DDS4.  [etc]
>>>> However, attached to either controller (after a reboot of the machine
>>> and a
>>>> powercycle of the drive), I get:
>>>> 
>>>> [1:25:325]root at run:/home/foo> dd if=/dev/sa0  of=tape5
>>>> dd: /dev/sa0: Input/output error
>>>> 0+0 records in
>>>> 0+0 records out
>>>> 0 bytes transferred in 0.002930 secs (0 bytes/sec)
>>>> 
>>>> ... which is a return code of '1' and no messages on the console...
>>>> 
>>>> I have, before you ask, tried "bs=10k" and 20k ... but I believe this
>>>> command should run by itself fetching the first 512 bytes of each block
>>> ---
>>>> narrowing down the block size logically comes after making the tape go.
>>> 
>>> 
>>> Try bs=64k
>> 
>> Same result.  Besides, as far as I understand, the proper operation
>> (if the blocksize is too small) is to read the first $n bytes and
>> then write them to the output..

My (dim) memory says the drive won't read at all if you get the blocksize wrong, so may be worth trying other sizes...

> The obvious question: can you write tapes and read them back?

...but certainly try that.

> My
> experience with DDS tapes was of extreme unreliability.  The age
> doesn't make things any easier.

There's a lot to go wrong with settings etc. See for instance: http://fixunix.com/setup/398541-dds-4-tape-drive-compatiblity.html

> Greg
> --
> Sent from my desktop computer.
> Finger grog at FreeBSD.org for PGP public key.
> See complete headers for address and phone numbers.
> This message is digitally signed.  If your Microsoft MUA reports
> problems, please read http://tinyurl.com/broken-mua

--
Bob Bishop
rb at gid.co.uk