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dd / cpio backup problem

bzimmermann
bzimmermann asked
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Last Modified: 2008-03-06
The following script returns sometimes an error-Code

rsh -n server " cd /; find . -print| grep -v \"^./cdrom/\"  \
        | grep -v \"^./home/\"  \
        | grep -v \"^./usr/\"  \
        | cpio -o -c -B " \
| dd of=/dev/rmt/0 bs=5k
(time for backup: total 4h )

1) dd returns sometimes an "dd: unexpected short write wrote 0 bytes,expected 5120".Is this an error ?
2) Is it possible that cpio is not working correctly if some files were deleted/changed during backup ?
thanks for help
Bernd
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Commented:
1) Nope, it's a warning message, you are trying to write
  with dd an empty output from cpio, then it's a cpio error.

2) Yep, that's because you are using too many pipelines and
  a slow tape write, you should try making it faster, with
  a local find, and checking the output before doing the cpio/dd
  pipe.


example: rsh -n server "(find [dir_list] -print \
        | cpio -o -c -B 2>/dev/null )" \
        | dd of=/dev/rmt/0 bs=5k

thus avoiding the serach on wrong directories, and the error
processing, maybe you should add a file existence checking
before the cpio with an:  xargs if [-f $1] ....
or something similar, depending on your shell...

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Author

Commented:
change cpio ... 2>/dev/null
into   cpio ... 2>/tmpfile_on_remote_host
to get the error message of the cpio
(in this case a broken pipe)
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