porblem with "dd" command?

[Jianlin Chang]

I use the following command to create a backup of remote system on local tape drive:
rsh remote tar cvfb - 2 .|dd of=/dev/rmt0.1 bs=2b

But it doesn't work. The error was:
dd: 0511-053 The write failed.
: A system call received a parameter that is not valid.

Any suggestions? Thanks a lot.

[Tim Butler]

tvan...@imtn.dsccc.com (Tim Vannaman) writes:

:Jianlin Chang (cha...@Jeff-Lab.QueensU.CA) wrote:
...
:: rsh remote tar cvfb - 2 .|dd of=/dev/rmt0.1 bs=2b

:: But it doesn't work. The error was:
:: dd: 0511-053 The write failed.
:: : A system call received a parameter that is not valid.

What type of tape device? What is the block size of the device set to?

If, for example, you have an 8mm drive configured with block size =0
(meaning variable), then asking for any size block should be ok.
(including 2b=2*512=1024)

If it is set to something odd, then you must reset it or set bs = to
a multiple of that cofigured block size.

run 'lsattr -l rmt0 -E' to find out the device configuration.

tim butler tbu...@tiac.net

[Jianlin Chang]

It's pretty strange that
rsh ...|dd of=... ibs=2b obs=2b
works.

Any suggestion?

tvan...@imtn.dsccc.com (Tim Vannaman) wrote:
>
> Jianlin Chang (cha...@Jeff-Lab.QueensU.CA) wrote:
> : I use the following command to create a backup of remote system on local tape drive:

> : rsh remote tar cvfb - 2 .|dd of=/dev/rmt0.1 bs=2b
>
> : But it doesn't work. The error was:
> : dd: 0511-053 The write failed.
> : : A system call received a parameter that is not valid.
>

> : Any suggestions? Thanks a lot.
>
> 1. Make sure the tape is writeable !!!!
> 2. Try the dd cmd w/o the bs arg.
>

[AIXDUDE]

i received the same message when writing to a 9348 9-track. i changed the
block size on the device through smit to 0 variable. this worked for me.

dennis s.

[chol...@googlemail.com]

On Wednesday, May 31, 1995 at 8:00:00 AM UTC+1, Jianlin Chang wrote:
> It's pretty strange that
> rsh ...|dd of=... ibs=2b obs=2b
> works.
>
> Any suggestion?
>
>
>

I know this post is over 20 years old but it sure helped me; we are still wrestling with tape backups of an AIX 4.5 system. We had the following command to backup our data to tape,

tar -cvf- * | dd of=/dev/rmt2 bs=512k

However, we also wanted backup to a file so was trying,

tar -cvf- * | tee /backup/data.tar | dd of=$tapedrv bs=512k

But was getting same error mentioned here.

Guided by this post that mentioned using ibs and obs to specify the block size, I tried,

tar -cvf- * | tee /backup/data.tar | dd of=$tapedrv obs=512k (not knowing the input blocksize),

and it worked!!

My guess is that tee changed the blocksize of the stdout to the pipe, and that dd was expecting 512k. By allowing dd to only specify the output blocksize made this work.

Thanks