Rescuing mangled RAID5 array

[Greg Eden]

Hello

I'm trying to recover data from a broken RAID5 array (drive removed  
whilst array was rebuilding!).

What's the best way to get an image of the corrupted partition and  
how would I run fsck -y on the image. The corrupted partition is  
1.3TB, /dev/da1s1d, usually mounted as /raid. I have another empty  
2TB partition handy, /dev/da2s1d currently mounted as /raid2.

Following this thread

http://lists.freebsd.org/pipermail/freebsd-questions/2006-November/ 
134984.html

I'm trying

dd if=/dev/da1s1d of=/raid2/rescueimage

but it's proceeding very slowly (2MB/sec) and I'm not entirely sure  
I'm going to be able to mount and fix the resulting image with fsck  
at the end of it.

So is there a faster way to clone a partition (unfortunately the  
drive array itself doesn't offer this functionality) and can you fsck  
an md mounted image. assuming i should use md to mount the image?

There's nothing wrong with the drives physically, just mangled  
metadata I think. I can actually mount the partition readonly but  
many directories are missing or listed as 'Bad file descriptor'. I've  
copied about 20% of the data off but the most important 50% doesn't  
even have it's directory listed any more :(

Thanks in advance for any help

Greg.