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Subject: Re: increasing dd disk to disk transfer rate
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Bakul Shah wrote:
>>In the last episode (Jan 12), Christoph Kukulies said:

>>dd if=/dev/ad2 conv=noerror,sync bs=64k | dd of=/dev/ad3 bs=64k
> 
> 
> So now on the new disk he has files with random blocks of
> zeroes and *no* error indication of which files are so
> trashed.  This is asking for trouble.  Silent erros are
> worse.
> 
> He ought to do a file level copy, not disk level copy on
> unix.  That way he knows *which* files are trashed and can do

The problem is, FreeBSD panics when it encounters bad sectors in 
filesystem metadata. I had the same situation ~a month ago and gave up, 
restoring from old backups. It will also probably panic on corrupted or 
zeroed metadata, but at least it's on a readable disk...