[ale] writing to tape

[Scott Castaline]

On 02/02/2010 01:59 PM, Greg Freemyer wrote:
> 2010/2/2 Björn Gustafsson<bg-ale at bjorng.net>:
>> On Mon, Feb 1, 2010 at 10:31 AM, Geoffrey<lists at serioustechnology.com>  wrote:
>>> Greg Freemyer wrote:
>>>> What's your command line including pipes.
>>>
>>> ssh servername "tar -cf - $BackupThis" | dd bs=10k of=/dev/nst0
>>
>> I don't know if it works with GNU tar, but you might want to try the
>> -B switch and/or to set `-b 20' to explicitly match the dd blocksize.
>> (20 should be the default though.)
>>
>> After quickly checking the GNU tar manpage, it seems to indicate that
>> -B only works for reads, but it might be worth a try anyway.
>>
>> --
>> Björn Gustafsson
>
> tar is not the problem.  Its whatever the interconnect is between the machines.
>
> It is not keeping up with the tape drive so dd is stalling out on the
> input from the comm channel and creating partial blocks on its output.
>   dd is just not really a good tool for this use case.
>
> I've come across similar issues in the past.  My solution was to us
> mbuffer as I said in a previous email.
>
> I think this is what I used<http://www.maier-komor.de/mbuffer.html>
> but it was years ago.  Back then it was not really well supported and
> I had to patch in some fixes..  To my surprise it is now in the
> opensuse distro, so maybe others as well.
>
> Greg
It's also available for Fedora:

[scott at ncc1701 ~]$ yum list mbuffer
Loaded plugins: fastestmirror, presto, refresh-packagekit
Available Packages
mbuffer.x86_64              20091122-1.fc12                      updates