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Edward Ned Harvey 11-10-2010 10:38 PM

Challenge: dump | restore
 
This runs for a few minutes, and results in a broken pipe.* After which, at least some fragments of the filesystem have been restored on the destination filesystem.* At least some directories.
cd /mnt/newFS
dump -0af - /dev/someVG/sourceFS | restore -rf -
*
This works fine.
cd ~
dump -0af somefile /dev/someVG/sourceFS
cd /mnt/newFS
restore -rf ~/newFS
*
Source and destination filesystems are ext3, 194G and 857G.* Destination filesystem is created with simply default mkfs.ext3.* There are only approx.
200M used in the source filesystem, of which, there's no particularly huge directory or number of inodes or anything unusual...* I forced the fsck, and it came back clean.

My only guess is that there seems to be something wrong with the pipe.* Like, it's not streaming the bits properly or something.* Is it possible to overflow a pipe or something?* I can't think of any good explanation for this weird behavior.* What could cause a pipe to break, aside from the receiving process terminating unexpectedly?
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Bodo Thiesen 11-13-2010 02:40 PM

Challenge: dump | restore
 
* Edward Ned Harvey <kernel@nedharvey.com> hat geschrieben:
> dump -0af - /dev/someVG/sourceFS | restore -rf -
> My only guess is that there seems to be something wrong with the pipe.
> Like, it's not streaming the bits properly or something. Is it possible to
> overflow a pipe or something?

The sending process should block until the receiving process reads the
data.

> I can't think of any good explanation for
> this weird behavior. What could cause a pipe to break, aside from the
> receiving process terminating unexpectedly?

I recommend using strace to trace it down:

strace -f -o dump.strace dump -0af - /dev/someVG/sourceFS |
strace -f -o restore.strace restore -rf -

Then take a closer look on the tails of the two files, maybe that reveals
the problem already.

Regards, Bodo

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Stephen Samuel 11-16-2010 10:12 AM

Challenge: dump | restore
 
Try :

cd ~

dump -0af -* /dev/someVG/sourceFS | ( cd /mnt/newFS; restore -rf - ~/newFS )



On Wed, Nov 10, 2010 at 3:38 PM, Edward Ned Harvey <kernel@nedharvey.com> wrote:


This runs for a few minutes, and results in a broken pipe.* After which, at least some fragments of the filesystem have been restored on the destination filesystem.* At least some directories.


cd /mnt/newFS

dump -0af - /dev/someVG/sourceFS | restore -rf -

*

This works fine.

cd ~

dump -0af somefile /dev/someVG/sourceFS

cd /mnt/newFS

restore -rf ~/newFS

*


Source and destination filesystems are ext3, 194G and 857G.* Destination filesystem is created with simply default mkfs.ext3.* There are only approx.

200M used in the source filesystem, of which, there's no particularly huge directory or number of inodes or anything unusual...* I forced the fsck, and it came back clean.




My only guess is that there seems to be something wrong with the pipe.* Like, it's not streaming the bits properly or something.* Is it possible to overflow a pipe or something?* I can't think of any good explanation for this weird behavior.* What could cause a pipe to break, aside from the receiving process terminating unexpectedly?


--
Stephen Samuel http://www.bcgreen.com* Software, like love,
778-861-7641* * * * * * * * * * * * * * * grows when you give it away


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