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Re: [linux-lvm] Disk crash on LVM



Ray Morris <support bettercgi com> wrote:
> [...]
>    Then dd from the old copy of the LV to the new:
> 
> dd if=/dev/org/$1 bs=64M iflag=direct | 
> dd of=/dev/copy/$1 bs=64M oflag=direct 
> 
>    That piped dd is 2-3 times faster than the "obvious" 
> way to run dd.
> [...]

The issue with dd is that if any read() fails, it skips the entry (64M) and doesn't write to the output, making the output file smaller than the input file.

with conv=sync,noerror, it's better, but, still loosing a whole 64M block at once is a bad thing.

That's why I think dd_rescue would be better.
<http://www.garloff.de/kurt/linux/ddrescue/>

If it still gets warm too fast, I've heard that storing the hard drive in a freezer 24 hours may make it work again.
<http://geeksaresexy.blogspot.com/2006/01/freeze-your-hard-drive-to-recover-data.html>

If it crashes when dd or dd_rescue fails, it's possible to continue copying later, from the point it failed.

-- 
André Gillibert




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